SECTION VII

Agent Summary Statements

•	Parasitic Agents

Agent:	Nematode Parasites of Humans

	Laboratory-associated infections with Ascaris spp.; Strongyloides spp.; hookworms; and Enterobius spp. have been reported.91,110,151  Allergic reactions to various antigenic components of nematodes (e.g., aerosolized Ascaris antigens) may represent an individual risk to sensitized persons.  Laboratory animal-associated infections (including arthropods) have not been reported, but infective larvae in the feces of nonhuman primates infected with Strongyloides spp. are a potential infection hazard for laboratory and animal care personnel.

	Laboratory Hazards:  Eggs and larvae in freshly passed feces of infected hosts are usually not infective; development to the infective stages may take periods of one day to several weeks.  Trichinella is of concern since fresh or digested tissue may contain larvae and would be infective if ingested.  Ingestion of the infective eggs or skin penetration of infective larvae are the primary hazards to laboratory and animal care personnel.  Arthropods infected with filarial parasites pose a potential hazard to laboratory personnel.  In laboratory personnel with frequent exposure to aerosolized antigens of Ascaris spp. development of hypersensitivity is common.

	Recommended Precautions:  Biosafety Level 2 practices and facilities are recommended for activities with infective stages listed.  Exposure to aerosolized sensitizing antigens of Ascaris spp. should be avoided.  Primary containment (e.g., biological safety cabinet) may be required for work with these materials by hypersensitive individuals.  Appropriate treatment for most nematode infections exists, and information on dosage, source of drugs, etc. is available.5  

Agent:	Protozoal Parasites of Humans
	Laboratory-associated infections with Toxoplasma spp.; Plasmodium spp. (including P. cynomologi); Trypanosoma spp.; Entamoeba spp.; Coccidia spp.; Giardia spp.; Leishmania spp.; Sarcocystis spp.; and Cryptosporidia spp. have been reported.29,68,91,110,151,162  In addition, no laboratory infections with Babesia spp. or Microsporidia spp. have been reported but could result from accidental needlestick or ingestion of cysts, oocysts, or spores in feces.

	Although laboratory animal-associated infections have not been reported, a direct source of infection for laboratory personnel may be contact with lesion material from rodents with cutaneous leishmaniasis and with feces or blood of experimentally or naturally infected animals.

	Laboratory-related infections with Cryptosporidia have occurred with regularity in almost every laboratory working with this agent, especially those in which calves are utilized as the source of oocysts.  Other experimentally-infected animals pose potential risks as well.  There is circumstantial evidence that airborne transmission of oocysts of this small organism may occur.  Rigid adherence to protocol should reduce the occurrence in laboratory and animal care personnel.

	Laboratory Hazards: Infective stages may be present in blood, feces, lesion exudates, and infected arthropods.  Depending on the parasite, ingestion, skin penetration through wounds or microabrasions, accidental parenteral inoculation, and transmission by arthropod vectors are the primary laboratory hazards.  Aerosol or droplet exposure of the mucous membranes of the eyes, nose, or mouth with trophozoites are potential hazards when working with cultures of Naegleria fowleri, Leishmania spp., T. cruzi, or with tissue homogenates or blood containing hemoflagellates.  Immunocompromised individuals should avoid working with live organisms.  Because of the grave consequences of toxoplasmosis in the developing fetus, serologically negative women of childbearing age who might become pregnant should not work with Toxoplasma in the same laboratory room where these materials are handled.

	Recommended Precautions:  Biosafety Level 2 practices and facilities are recommended for activities with infective stages of the parasites listed.  Infected arthropods should be maintained in facilities which reasonably preclude the exposure of personnel or their escape to the outside.  Primary containment (e.g., biological safety cabinet) or personal protection (e.g., face shield) may be indicated when working with cultures of Naegleria fowleri, Leishmania spp., T. cruzi or with tissue homogenates or blood containing hemoflagellates.81  Gloves are recommended for activities where there is the likelihood of direct skin contact with infective stages of the parasites listed.  Appropriate treatment for most protozoal infections exists, and information on dosage, source of drugs, etc., is available.5

Agent:	Trematode Parasites of Humans (Schistosoma spp. and Fasciola spp.)

	Laboratory-associated infections with Schistosoma spp. and Fasciola spp. have been reported, none associated directly with laboratory animals.91,110,151

	Laboratory Hazards:  Infective stages of Schistosoma spp. (cercariae) and Fasciola spp. (metacercaria) may be found, respectively, in the water or encysted on aquatic plants in laboratory aquaria used to maintain snail intermediate hosts.  Skin penetration by schistosome cercariae and ingestion of fluke metacercaria are the primary laboratory hazards.  Dissection or crushing of schistosome-infected snails may also result in exposure of skin or mucous membrane to cercariae-containing droplets.  Additionally, metacercaria may be inadvertently transferred from hand to mouth by fingers or gloves following contact with contaminated aquatic vegetation or surfaces of aquaria.  Most laboratory exposures to Schistosoma spp. would predictably result in low worm burdens with minimal disease potential.  Safe and effective drugs are available for the treatment of schistosomiasis.

	Recommended Precautions:  Biosafety Level 2 practices and facilities are recommended for activities with infective stages of the parasites listed.  Gloves should be worn when there may be direct contact with a water containing cercariae, or vegetation containing metacercaria from naturally or experimentally infected snail intermediate hosts.  Long-sleeved laboratory coats or other protective garb should be worn when working arouquaria or other water sources that may contain schistosome cercariae.   Snails and cercariae in the water of laboratory aquaria should be killed by chemicals (e.g., hypochlorites, iodine) or heat before discharge to sewers.  Appropriate treatment for most trematode infections exists, and information on source of drugs, dosage, etc. is available.5

Agent:	Cestode Parasites of Humans - Echinococcus granulosus, Taenia solium (cysticercus cellulosae) and Hymenolepsis nana.

	Although no laboratory-associated infections with either E. granulosus or T. solium have been reported, the consequences of such infections following the ingestion of infective eggs of E. granulosus or T. solium are potentially grave.  H. nana is a very cosmopolitan parasite, does not require an intermediate host, and is directly transmissible by ingestion of feces of infected humans or rodents.

	Laboratory Hazards:  Infective eggs may be present in the feces of dogs or other canids (the definitive hosts of E. granulosus), or in the feces of humans (the definitive host of T. solium).  Ingestion of infective eggs from these sources are the primary laboratory hazard.  Cysts and cyst fluids of E. granulosus are not infectious for humans.  Ingestion of cysts containing the larval stage of T. solium (Cysticercus cellulosae) readily produces human infection with the adult tapeworm.  With either parasite, the ingestion of a single infective egg from the feces of the definitive host could potentially result in serious disease.  Ingestion of the eggs of H. nana in the feces of the definitive host could result in intestinal infection.

	Recommended Precautions:  Biosafety Level 2 practices and facilities are recommended for work with infective stages of these parasites.  Special attention should be given to personal hygiene practices (e.g., handwashing) and avoidance of ingestion of infective eggs.  Gloves are recommended when there may be direct contact with feces or surfaces contaminated with fresh feces of dogs infected with E. granulosus, humans infected with T. solium adults, or humans or rodents infected with H. nana.  Appropriate treatment for many cestode infections exists, and information concerning source of drugs, dosage, etc., is available.5

•	Fungal Agents

Agent:	Blastomyces dermatitidis

	Laboratory-associated local infections following accidental parenteral inoculation with infected tissues or cultures containing yeast forms of B. dermatitidis67,87,107,108,168,199 have been reported.  Pulmonary infections have occurred following the presumed inhalation of conidia; two developed pneumonia and one had an osteolytic lesion from which B. dermatitidis was cultured.9,58  Presumably, pulmonary infections are associated only with sporulating mold forms (conidia).

	Laboratory Hazards:  Yeast forms may be present in the tissues of infected animals and in clinical specimens.  Parenteral (subcutaneous) inoculation of these materials may cause local granulomas.  Mold form cultures of B. dermatitidis containing infectious conidia may pose a hazard of aerosol exposure.

	Recommended Precautions:  Biosafety Level 2 and Animal Biosafety Level 2 practices and facilities are recommended for activities with clinical materials, animal tissues, cultures, and infected animals.

Agent:	Coccidioides immitis

	Laboratory-associated coccidioidomycosis is a documented hazard.18,56,59,60,61,105,113,133,171,172,173  Smith reported that 28 of 31 (90%) laboratory-associated infections in his institution resulted in clinical disease, whereas more than half of infections acquired in nature were asymptomatic.200

	Laboratory Hazards:  Because of the size (2-5 millimicrons), the arthroconidia are conducive to ready dispersal in air and retention in the deep pulmonary spaces.  The much larger size of the spherule (30-60 millimicrons) considerably reduces the effectiveness of this form of the fungus as an airborne pathogen.

	Spherules of the fungus may be present in clinical specimens and animal tissues, and infectious arthroconidia in mold cultures and soil samples.  Inhalation of arthroconidia from soil samples, mold cultures, or following transformation from the spherule form in clinical materials, is the primary laboratory hazard.  Accidental percutaneous inoculation of the spherule form may result in local granuloma formation.184  Disseminated disease occurs at a much greater frequency in blacks and Filipinos than whites.

	Recommended Precautions:  Biosafety Level 2 practices and facilities are recommended for handling and processing clinical specimens, identifying isolates, and processing animal tissues.  Animal Biosafety Level 2 practices and facilities are recommended for experimental animal studies when the route of challenge is parenteral.

	Biosafety Level 3 practices and facilities are recommended for propagating and manipulating sporulating cultures already identified as C. immitis and for processing soil or other environmental materials known or likely to contain infectious arthroconidia.

Agent:	Cryptococcus neoformans

	A single account is reported of a laboratory exposure to Cryptococcus neoformans as a result of a laceration by a scalpel blade heavily contaminated with encapsulated cells.83  This vigorous exposure, which did not result in local or systemic evidence of infection, suggests that the level of pathogenicity for normal immunocompetent adults is low.  Respiratory infections as a consequence of laboratory exposure have not been recorded.

	Laboratory Hazards: Accidental parenteral inoculation of cultures or other infectious materials represents a potential hazard to laboratory personnel -- particularly to those that may be immunocompromised.  Bites by experimentally infected mice and manipulations of infectious environmental materials (e.g., pigeon droppings) may also represent a potential hazard to laboratory personnel.
	Recommended Precautions: Biosafety Level 2 and Animal Biosafety Level 2 practices and facilities are recommended, respectively, for activities with known or potentially infectious clinical, environmental, or culture materials and with experimentally infected animals.

	The processing of soil or other environmental materials known or likely to contain infectious yeast cells should be conducted in a Class I or Class II biological safety cabinet.  This precaution is also indicated for culture of the perfect or sexual state of the agent.

Agent:	Histoplasma capsulatum

	Laboratory-associated histoplasmosis is a documented hazard in facilities conducting diagnostic or investigative work.151,152  Pulmonary infections have resulted from handling mold form cultures.132  Local infection has resulted from skin puncture during autopsy of an infected human185 and from accidental needle inoculation of a viable culture.182  Collecting and processing soil samples from endemic areas has caused pulmonary infections in laboratory workers.  Encapsulated spores are resistant to drying and may remain viable for long periods of time.  The small size of the infective conidia (less than 5 microns) is conducive to airborne 
dispersal and intrapulmonary retention.  Furcolow reported that 10 spores were almost as effective as a lethal inoculum in mice as 10,000 to 100,000 spores.75

	Laboratory Hazards:  The infective stage of this dimorphic fungus (conidia) is present in sporulating mold form cultures and in soil from endemic areas.  The yeast form in tissues or fluids from infected animals may produce local infection following parenteral inoculation.

	Recommended Precautions:  Biosafety Level 2 and Animal Biosafety Level 2 practices and facilities are recommended for handling and processing clinical specimens, identifying isolates, animal tissues and mold cultures, identifying cultures in routine diagnostic laboratories, and for experimental animal studies when the route of challenge is parenteral.
	Biosafety Level 3 practices and facilities are recommended for propagating and manipulating cultures already identified as H. capsulatum, as well as processing soil or other environmental materials known or likely to contain infectious conidia.  

Agent:	Sporothrix schenckii

	S. schenckii has caused a substantial number of local skin or eye infections in laboratory personnel.  Most cases have been associated with accidents and have involved splashing culture material into the eye,69,197 scratching21 or injecting183 infected material into the skin or being bitten by an experimentally infected animal.100,101  Skin infections have resulted also from handling cultures57,124,137 or necropsy of animals73 without a known break in technique.  No pulmonary infections have been reported to result from laboratory exposure, although naturally occurring lung disease is thought to result from inhalation.

	Recommended Precautions: Biosafety Level 2 and Animal Biosafety Level 2 practices and facilities are recommended for all laboratory and experimental animal activities with S. schenckii.  Gloves should be worn when handling experimentally infected animals, and during operations with broth cultures that might result in hand contamination.

Agents:	Pathogenic Members of the Genera Epidermophyton, Microsporum and Trichophyton

	Although skin, hair and nail infections by these dermatophytid molds are among the most prevalent of human infections, the processing of clinical material has not been associated with laboratory infections.  Infections have been acquired through contacts with naturally or experimentally infected laboratory animals (mice, rabbits, guinea pigs, etc.) and, rarely, with handling cultures.84,119,151

	Laboratory Hazards:  Agents are present in the skin, hair and nails of human and animal hosts.  Contact with infected laboratory animals with inapparent or apparent infections is the primary hazard to laboratory personnel.  Cultures and clinical materials are not an important source of human infection.

	Recommended Precautions: Biosafety Level 2 and Animal Biosafety Level 2 practices and facilities are recommended for all laboratory and experimental animal activities with dermatophytes.  Experimentally infected animals should be handled with disposable gloves.

Agent:	Miscellaneous Molds

	Several molds have caused serious infection in immunocompetent hosts following presumed inhalation or accidental subcutaneous inoculation from environmental sources.  These agents are Cladosporium (Xylohypha) trichoides, Cladosporium bantianum, Penicillium marnefii, Exophiala (Wangiella) dermatitidis, Fonsecaea pedrosoi and Dactylaria gallopava (Ochroconis gallopavum).  Even though no laboratory acquired infections appear to have been reported with most of these agents, the gravity of naturally acquired illness is sufficient to merit special precautions in the laboratory.  Penicillium marnefii has caused a local inoculation infection in a laboratory worker.169

	Laboratory Hazards: Inhalation of conidia from sporulating mold cultures or accidental injection into the skin during infection or experimental animals is a theoretical risk to laboratory personnel.

	Recommended Precautions: Biosafety Level 2 practices and facilities are recommended for propagating and manipulating cultures known to contain these agents.

•	Bacterial Agents

Agent:	Bacillus anthracis

	Forty (40) cases of laboratory-associated anthrax, occurring primarily at facilities conducting anthrax research, have been reported.66,151  No laboratory-associated cases of anthrax have been reported in the United States since the late 1950's when human anthrax vaccine was introduced.

	Naturally and experimentally infected animals pose a potential risk to laboratory and animal care personnel.

	Laboratory Hazards:  The agent may be present in blood, skin lesion exudates, cerebrospinal fluid, pleural fluid, sputum, and rarely, in urine and feces.  Direct and indirect contact of the intact and broken skin with cultures and contaminated laboratory surfaces, accidental parenteral inoculation, and rarely, exposure to infectious aerosols are the primary hazards to laboratory personnel.

	Recommended Precautions:  Biosafety Level 2 practices, containment equipment and facilities are recommended for activities using clinical materials and diagnostic quantities of infectious cultures.  Animal Biosafety Level 2 practices, containment equipment and facilities are recommended for studies utilizing experimentally infected laboratory rodents.  A licensed vaccine is available through the Centers for Disease Control and Prevention; however, immunization of laboratory personnel is not recommended unless frequent work with clinical specimens or diagnostic cultures is anticipated (e.g., animal disease diagnostic laboratory).  Biosafety Level 3 practices, containment equipment and facilities are recommended for work involving production volumes or concentrations of cultures, and for activities which have a high potential for aerosol production.  In these facilities immunization is recommended for all persons working with the agent, all persons working in the same laboratory room where the cultures are handled, and persons working with infected animals.

Agent:	Bordetella pertussis

	Bordetella pertussis, a human respiratory pathogen of worldwide distribution, is the causative agent of whooping cough.  The disease is typically a childhood illness; however, the agent has been associated, with increased frequency, in adult illness.106,112,130  Several outbreaks in health-care workers have been reported in the literature.106,112  Adolescents and adults with atypical or undiagnosed disease can serve as reservoirs of infection and transmit the organism to infants and children.135  Eight cases of infection with B. pertussis in adults have been documented at a large research institution.  The individuals involved did not work directly with the organism, but had access to common laboratory spaces where the organism was manipulated.  One case of secondary transmission to a family member was documented.122  A similar incident occurred at a large midwestern university resulting in two documented cases of laboratory-acquired infection and one documented case of secondary transmission.146  Other laboratory-acquired infections with B. pertussis have been reported, as well as adult-to-adult transmission in the workplace.19,35  Laboratory-acquired infections resulting from the manipulation of clinical specimens or isolates have not been reported.  The attack rate of this airborne infection is influenced by intimacy and frequency of exposure of susceptible individuals.

	Laboratory Hazards:  The agent may be present in respiratory secretions, but is not found in blood or tissues.  Since the natural mode of transmission is by the respiratory route, the greatest potential hazard is aerosol generation during the manipulation of cultures or concentrated suspensions of the organism.

	Recommended Precautions:  Biosafety Level 2 practices, containment equipment, and facilities are recommended for all activities involving the use or manipulation of known or potentially infectious clinical materials or cultures.  Animal Biosafety Level 2 should be used for the housing of infected animals.  Primary containment devices and equipment (e.g., biological safety cabinets, centrifuge safety cups, or specially designed safety centrifuges) should be used for activities likely to generate potentially infectious aerosols.  Biosafety Level 3 practices, procedures, and facilities are appropriate when engaged in large scale production operations.  The current pertussis vaccine may not provide complete and permanent immunity; however, a booster dose of pertussis vaccine is not recommended for use in persons who have passed their seventh birthday.50

Agent:	Brucella (B. abortus, B. canis, B. melitensis, B. suis)

	B. abortus, B. canis, B. melitensis, and B. suis have all caused illness in laboratory personnel.129,151,176  Brucellosis is the most commonly reported laboratory-associated bacterial infection.127,143,151  Hypersensitivity to Brucella antigens is also a hazard to laboratory personnel.  Occasional cases have been attributed to exposure to experimentally and naturally infected animals or their tissues.

	Laboratory Hazards:  The agent may be present in blood, cerebrospinal fluid, semen, and occasionally urine.  Most laboratory-associated cases have occurred in research facilities and have involved exposure to Brucella organisms being grown in large quantities.  Cases have also occurred in a clinical laboratory setting: direct skin contact with cultures or with infectious clinical specimens from animals (e.g., blood, uterine discharges) are commonly implicated in these cases.  Aerosols generated during laboratory procedures have caused large outbreaks.95  Mouth pipetting, accidental parenteral inoculations, and sprays into eyes, nose and mouth have also resulted in infection.

	Recommended Precautions:  Biosafety Level 2 practices are recommended for activities with clinical specimens of human or animal origin containing or potentially containing pathogenic Brucella spp.  Biosafety Level 3 and Animal Biosafety Level 3 practices, containment equipment and facilities are recommended, respectively, for all manipulations of cultures of the pathogenic Brucella spp. listed in this summary, and for experimental animal studies.  Vaccines are not available for use in humans.

Agent:	Campylobacter (C. jejuni/C. coli, C. fetus subsp. fetus)

	C. jejuni/C. coli gastroenteritis is rarely a cause of laboratory associated illness.  Three laboratory-acquired cases have been documented.138,149,155  Numerous domestic and wild animals, including poultry, pets, farm animals, laboratory animals, and wild birds are known reservoirs and are a potential source of infection for laboratory and animal care personnel.  Experimentally infected animals are also a potential source of infection.155

Laboratory Hazards:  Pathogenic campylobacters may occur in fecal specimens in large numbers.  C. fetus subsp. fetus may also be present in blood, exudates from abscesses, tissues, and sputa.  Ingestion or parenteral inoculation of C. jejuni constitute the primary laboratory hazards.  The oral ingestion of 500 organisms caused infection in one individual.163  The importance of aerosol exposure is not known.

	Recommended Precautions:  Biosafety level 2 practices, containment equipment and facilities are recommended for activities with cultures or potentially infectious clinical materials.  Animal Biosafety Level 2 practices, containment equipment and facilities are recommended for activities with naturally or experimentally infected animals.  Vaccines are not available for use in humans.

Agent:	Chlamydia psittaci, C. pneumoniae,  C. 	
trachomatis

	Infections with psittacosis, lymphogranuloma venereum (LGV), and trachoma are documented hazards and among the most commonly reported laboratory-associated bacterial infection.  In one report,151 the majority of cases were psittacosis, occurred before 1955, and had the highest case fatality rate of all groups of infectious agents. Additional cases of laboratory-acquired psittacosis have been documented more recently.127  Contact with and exposure to infectious aerosols in the handling, care, or necropsy of naturally or experimentally infected birds are the major sources of laboratory-associated psittacosis.  Infected mice and eggs are less important sources of C. psittaci.  Laboratory animals are not a reported source of human infection with C. trachomatis.

	Laboratory Hazards:  C. psittaci may be present in the  tissues, feces, nasal secretions and blood, of infected birds and in blood, sputum, and tissues of infected humans.  C. trachomatis may be present in genital, bubo, and conjunctival fluids of infected humans.  Exposure to infectious aerosols and droplets, created during the handling of infected birds and tissues, are the primary hazards to laboratory personnel working with psittacosis.  The primary laboratory hazards of C. trachomatis are accidental parenteral inoculation and direct and indirect exposure of mucous membranes of the eyes, nose, and mouth to genital, bubo, or conjunctival fluids, cell culture materials, and fluids from infected eggs.  Infectious aerosols may also pose a potential source of infection.

	Recommended Precautions:  Biosafety Level 2 practices, containment equipment and facilities are recommended for activities involving the necropsy of infected birds and the diagnostic examination of tissues or cultures known or potentially infected with C. psittaci or C. trachomatis.  Wetting the feathers of infected birds with a detergent-disinfectant prior to necropsy can appreciably reduce the risk of aerosols of infected feces and nasal secretions on the feathers and external surfaces of the bird.  Animal Biosafety Level 2 practices, containment equipment and facilities and respiratory protection are recommended for personnel working with naturally or experimentally infected caged birds.  Gloves are recommended for the necropsy of birds and mice, the opening of inoculated eggs, and when there is the likelihood of direct skin contact with infected tissues, bubo fluids, and other clinical materials.  Additional primary containment and personnel precautions, such as those recommended for Biosafety Level 3, may be indicated for activities with high potential for droplet or aerosol production and for activities involving production quantities or concentrations of infectious materials.  Vaccines are not available for use in humans.

Agent:	Clostridium botulinum

	While there is only one report177 of botulism associated with the handling of the agent or toxin in the laboratory or working with naturally or experimentally infected animals, the consequences of such intoxications must still be considered quite grave.

	Laboratory Hazards:  C. botulinum or its toxin may be present in a variety of food products, clinical materials (serum, feces) and environmental samples (soil, surface water).  Exposure to the toxin of C. botulinum is the primary laboratory hazard.  The toxin may be absorbed after ingestion or following contact with the skin, eyes, or mucous membranes, including the respiratory tract.93  Accidental parenteral inoculation may also represent a significant exposure to toxin.  Broth cultures grown under conditions of optimal toxin production may contain 2 X 106 mouse LD50 per mL.177

	Recommended Precautions:  Biosafety Level 2 practices, containment equipment and facilities are recommended for all activities with materials known or potentially containing the toxin.  A pentavalent (ABCDE) botulism toxoid is available through the Centers for Disease Control and Prevention, as an investigational new drug (IND).  This toxoid is recommended for personnel working with cultures of C. botulinum or its toxins.  Solutions of sodium hypochlorite (0.1%) or sodium hydroxide (0.1N) readily inactivate the toxin and are recommended for decontaminating work surfaces and spills of cultures or toxin.  Additional primary containment and personnel precautions, such as those recommended for Biosafety Level 3, are indicated for activities with a high potential for aerosol or droplet production, and those involving production quantities of toxin.  Animal Biosafety Level 2 practices, containment equipment and facilities are recommended for diagnostic studies and titration of toxin.

Agent:	Clostridium tetani

	Although the risk of infection to laboratory personnel is negligible, Pike151 has recorded 5 incidents related to exposure of personnel during manipulation of the toxin.

	Laboratory Hazards:  Accidental parenteral inoculation and ingestion of the toxin are the primary hazards to laboratory personnel.  It is uncertain if tetanus toxin can be absorbed through mucous membranes; consequently, the hazards associated with aerosols and droplets remain unclear.

	Recommended Precautions:  Biosafety Level 2 practices, containment equipment and facilities are recommended for activities involving the manipulation of cultures or toxin.  While the risk of laboratory-associated tetanus is low, the administration of an adult diphtheria-tetanus toxoid at 10-year intervals further reduces the risk to laboratory and animal care personnel of toxin exposures and wound contamination, and is therefore highly recommended.32

Agent:	Corynebacterium diphtheria

	Laboratory-associated infections with C. diphtheria are documented.  Pike151 lists 33 cases reported in the world literature.  Laboratory animal-associated infections have not been reported.

	Laboratory Hazards:  The agent may be present in exudates or secretions of the nose, throat (tonsil), pharynx, larynx, wounds, in blood, and on the skin.  Inhalation, accidental parenteral inoculation, and ingestion are the primary laboratory hazards.

	Recommended Precautions:  Biosafety Level 2 practices, containment equipment and facilities are recommended for all activities utilizing known or potentially infected clinical materials or cultures.  Animal Biosafety Level 2 facilities are recommended for studies utilizing infected laboratory animals.  While the risk of laboratory-associated diphtheria is low, the administration of an adult diphtheria-tetanus toxoid at 10-year intervals may further reduce the risk to laboratory and animal care personnel of toxin exposures and work with infectious materials.32

Agent:	Francisella tularensis

	Tularemia is the third most commonly reported laboratoryassociated bacterial infection.151  Almost all cases occurred at facilities involved in tularemia research.  Occasional cases have been related to work with naturally or experimentally infected animals or their ectoparasites.  Although not reported, cases have occurred in clinical laboratories.

	Laboratory Hazards:  The agent may be present in lesion exudate, respiratory secretions, cerebrospinal fluid, blood, urine, tissues from infected animals, and fluids from infected arthropods.  Direct contact of skin or mucous membranes with infectious materials, accidental parenteral inoculation, ingestion, and exposure to aerosols and infectious droplets have resulted in infection.  Cultures have been more commonly associated with infection than clinical materials and infected animals.  The human 25% to 50% infectious dose is approximately 10 organisms by the respiratory route.16
	
	Recommended Precautions:  Biosafety Level 2 practices, containment equipment and facilities are recommended for activities with clinical materials of human or animal origin containing or potentially containing Francisella tularensis.  Biosafety Level 3 and Animal Biosafety Level 3 practices, containment equipment and facilities are recommended, respectively, for all manipulations of cultures and for experimental animal studies.  An investigational live attenuated vaccine16 is available. It is recommended for persons working with the agent or infected animals, and for persons working in or entering the laboratory or animal room where cultures or infected animals are maintained.

Agent:	Leptospira interrogans - all serovars

	Leptospirosis is a well-documented laboratory hazard.  Pike151 reported 67 laboratory-associated infections and 10 deaths, and three additional cases have been reported elsewhere.127

	An experimentally infected rabbit was identified as the source of an infection with L. interrogans serovar icterohemorrhagiae.159  Direct and indirect contact with fluids and tissues of experimentally or naturally infected mammals during handling, care, or necropsy is a potential source of infection.  In animals with chronic kidney infections, the agent is shed in the urine in enormous numbers for long periods of time.

	Laboratory Hazards:  The agent may be present in urine, blood, and tissues of infected animals and humans.  Ingestion, accidental parenteral inoculation, and direct and indirect contact of skin or mucous membranes with cultures or infected tissues or body fluids -- especially urine -- are the primary laboratory hazards.  The importance of aerosol exposure is not known.

	Recommended Precautions:  Biosafety Level 2 practices, containment equipment and facilities are recommended for all activities involving the use or manipulation of known or potentially infectious tissues, body fluids, and cultures, and for the housing of infected animals.  Gloves are recommended for the handling and necropsy of infected animals, and when there is the likelihood of direct skin contact with infectious materials.  Vaccines are not available for use in humans.

Agent:	Legionella pneumophila; other Legionella-like agents

	A single documented nonfatal laboratory-associated case of legionellosis due to presumed aerosol or droplet exposure during animal challenge studies with Pontiac Fever agent (L. pneumophila) has been recorded.24  Human-to-human spread has not been documented.
	Experimental infections are readily produced in guinea pigs and embryonated chicken eggs.121  Challenged rabbits develop antibodies but not clinical disease.  Mice are refractory to parenteral exposure.  Unpublished studies by Kaufmann, Feeley and others at the Centers for Disease Control and Prevention have shown that animal-to-animal transmission did not occur in a variety of experimentally infected mammalian and avian species.

	Laboratory Hazards:  The agent may be present in pleural fluid, tissue, sputum, and environmental sources (e.g., cooling tower water).  Because the natural mode of transmission appears to be airborne, the greatest potential hazard is the generation of aerosols during the manipulation of cultures or of other materials containing high concentrations of infectious microorganisms (e.g., infected yolk sacs and tissues).

	Recommended Precautions:  Biosafety Level 2 practices, containment equipment and facilities are recommended for all activities involving the use or manipulation of known or potentially infectious clinical materials or cultures, and for the housing of infected animals.  Biosafety Level 3 practices with primary containment devices and equipment (e.g., biological safety cabinets, centrifuge safety cups) are used for activities likely to generate potentially infectious aerosols and for activities involving production quantities of microorganisms.  Vaccines are not available for use in humans.

Agent:	Mycobacterium leprae

	Inadvertent parenteral human to human transmission of leprosy following an accidental needle stick in a surgeon115 and the use of a presumably contaminated tattoo needle147 have been reported.  There are no cases reported as a result of working in a laboratory with biopsy or other clinical materials of human or animal origin.  While naturally occurring leprosy or leprosy-like diseases have been reported in armadillos189 and in nonhuman primates63,126 humans are the only known important reservoir of this disease.

	Laboratory Hazards:  The infectious agent may be present in tissues and exudates from lesions of infected humans and experimentally or naturally infected animals.  Direct contact of the skin and mucous membranes with infectious materials, and accidental parenteral inoculation, are the primary laboratory hazards associated with handling infectious clinical materials.
	Recommended Precautions:  Biosafety Level 2 practices, containment equipment and facilities are recommended for all activities with known or potentially infectious clinical materials from infected humans and animals.  Extraordinary care should be taken to avoid accidental parenteral inoculation with contaminated sharp instruments.  Animal Biosafety Level 2 practices, containment equipment and facilities are recommended for animal studies utilizing rodents, armadillos, and nonhuman primates.

Agent:	Mycobacterium spp. other than M. tuberculosis, M. bovis or M. leprae

	Pike reported 40 cases of nonpulmonary "tuberculosis" thought to be related to accidents or incidents in the laboratory or autopsy room.151  Presumably these infections were due to mycobacteria other than M. tuberculosis or M. bovis.  A number of mycobacteria which are ubiquitous in nature are associated with diseases, other than tuberculosis or leprosy, in humans, domestic animals, and wildlife.  Characteristically, these organisms are infectious but not contagious.  Clinically, the diseases associated with infections by these "atypical" mycobacteria can be divided into three general categories:

	1.	Pulmonary diseases resembling tuberculosis which may be associated with infection by M. kansasii, M. avium complex, and rarely, by  M. xenopi, M. malmoense, M. asiaticum, M. simiae and M. szulgai.

	2.	Lymphadenitis which may be associated with infection by M. scrofulaceum, M. avium complex, and rarely, by M. fortuitum and M. kansasii.

	3.	Skin ulcers and soft tissue wound infections which may be associated with infection by M. ulcerans, M. marinum, M. fortuitum, and M. chelonei.

	Laboratory Hazards:  The agents may be present in sputa, exudates from lesions, tissues, and in environmental samples (e.g., soil and water).  Direct contact of skin or mucous membranes with infectious materials, ingestion, and accidental parenteral inoculation are the primary laboratory hazards associated with clinical materials and cultures.  Infectious aerosols, created during the manipulation of broth cultures or tissue homogenates of these organisms associated with pulmonary disease, also pose a potential infection hazard to laboratory personnel.

	Recommended Precautions:  Biosafety Level 2 practices, containment equipment and facilities are recommended for activities with clinical materials and cultures of Mycobacterium spp. other than M. tuberculosis or M. bovis.  Animal Biosafety Level 2 practices, containment equipment and facilities are recommended for animal studies with mycobacteria other than M. tuberculosis, M. bovis, or M. leprae.

Agent:	Mycobacterium tuberculosis, M. bovis

	Mycobacterium tuberculosis and M. bovis infections are a proven hazard to laboratory personnel as well as others who may be exposed to infectious aerosols in the laboratory.79,127,131,151,154  The incidence of tuberculosis in laboratory personnel working with M. tuberculosis has been reported to be three times higher than those not working with the agent.156  Naturally or experimentally infected nonhuman primates are a proven source of human infection (e.g., the annual tuberculin conversion rate in personnel working with infected nonhuman primates is about 70/10,000 compared with less than 3/10,000 in the general population).102  Experimentally infected guinea pigs or  mice do not pose the same problem since droplet nuclei are not produced by coughing in these species; however, litter from infected animals may become contaminated and serve as a source of infectious aerosols.

	Laboratory Hazards:  Tubercle bacilli may be present in sputum, gastric lavage fluids, cerebrospinal fluid, urine, and in lesions from a variety of tissues.6  Exposure to laboratory-generated aerosols is the most important hazard encountered.  Tubercle bacilli may survive in heat-fixed smears1, and may be aerosolized in the preparation of frozen sections and during manipulation of liquid cultures.  Because of the low infective dose of M. tuberculosis for humans (i.e., ID50 <10 bacilli)160,161 and in some laboratories a high rate of isolation of acid-fast organisms from clinical specimens (>10%),77 sputa and other clinical specimens from suspected or known cases of tuberculosis must be considered potentially infectious and handled with appropriate precautions.

	Recommended Precautions:  Biosafety Level 2 practices, containment equipment and facilities are required for activities at American Thoracic Society (ATS) laboratory level I,3,4 preparation of acid-fast smears, and culturing of sputa or other clinical specimens, provided that aerosol generating manipulations of such specimens are conducted in a Class I or II biological safety cabinet.  Liquification and concentration of sputa for acid-fast staining may also be conducted safely on the open bench by first treating the specimen (in a Class I or II safety cabinet) with an equal volume of 5% sodium hypochlorite solution (undiluted household bleach) and waiting 15 minutes before centrifugation.142,174

	Biosafety Level 3 practices, containment equipment and facilities are required for laboratory activities of ATS levels II and III)3,4 in the propagation and manipulation of cultures of M. tuberculosis or M. bovis, and for animal studies utilizing nonhuman primates experimentally or naturally infected with M. tuberculosis or M. bovis.  Animal studies utilizing guinea pigs or mice can be conducted at Animal Biosafety Level 2.  Skin testing with purified protein devivatie (PPD) of previously skin-tested-negative laboratory personnel can be used as a surveillance procedure.  A licensed attenuated live vaccine (BCG) is available but is not routinely used in the United States for laboratory personnel.

Agent:	Neisseria gonorrhoeae

	Four cases of laboratory-associated gonorrhoea have been reported in the United States.62,151

	Laboratory Hazards:  The agent may be present in conjunctival, urethral and cervical exudates, synovial fluid, urine, feces, and cerebrospinal fluid.  Accidental parenteral inoculation and direct or 

indirect contact of mucous membranes with infectious clinical materials are the known primary laboratory hazards.  The importance of aerosols is not determined.

	Recommended Precautions:  Biosafety Level 2 practices, containment equipment and facilities are recommended for all activities involving the use or manipulation of clinical materials or cultures.  Gloves should be worn when handling infected laboratory animals and when there is the likelihood of direct skin contact with infectious materials.  Additional primary containment and personnel precautions, such as those described for Biosafety Level 3, may be indicated for aerosol or droplet production, and for activities involving production quantities or concentrations of infectious materials.  Vaccines are not available for use in humans.

Agent:	Neisseria meningitidis

	Meningococcal meningitis is a demonstrated but rare hazard to laboratory workers.8,49,153

	Laboratory Hazards:  The agent may be present in pharyngeal exudates, cerebrospinal fluid, blood, and saliva.  Parenteral inoculation, droplet exposure of mucous membranes, infectious aerosol and ingestion are the primary hazards to laboratory personnel.

	Recommended Precautions:  Biosafety Level 2 practices, containment equipment and facilities are recommended for all activities utilizing known or potentially infectious body fluids, tissues, and cultures.  Additional primary containment and personnel precautions such as those described for Biosafety Level 3, may be indicated for activities with high potential for droplet or aerosol production, and for activities involving production quantities or concentrations of infectious materials.  The use of licensed polysaccharide vaccines27 should be considered for personnel regularly working with large volumes or high concentrations of infectious materials.

Agent:	Pseudomonas pseudomallei

	Two laboratory-associated cases of melioidosis are reported:  one associated with a massive aerosol and skin exposure;78 the second resulting from an aerosol created during the open-flask sonication of a culture presumed to be Ps. cepacia.166a

	Laboratory Hazards:  The agent may be present in sputum, blood, wound exudates and various tissues depending on the infection's site of localization.  Direct contact with cultures and infectious materials from humans, animals, or the environment, ingestion, autoinoculation, and exposure to infectious aerosols and droplets are the primary laboratory hazards.  The agent has been demonstrated in blood, sputum, and abscess materials and may be present in soil and water samples from endemic areas.

	Recommended Precautions:  Biosafety Level 2 practices, containment equipment and facilities are recommended for all activities utilizing known or potentially infectious body fluids, tissues, and cultures.  Gloves should be worn when handling infected animals, during their necropsy, and when there is the likelihood of direct skin contact with infectious materials.  Additional primary containment and personnel precautions, such as those described for Biosafety Level 3, may be indicated for activities with a high potential for aerosol or droplet production, and for activities involving production quantities or concentrations of infectious materials.

Agent:	Salmonella - all serotypes except typhi

	Salmonellosis is a documented hazard to laboratory personnel.80,127,151  Primary reservoir hosts include a broad spectrum of domestic and wild animals, including birds, mammals, and reptiles, all of which may serve as a source of infection to laboratory personnel.

	Laboratory Hazards:  The agent may be present in feces, blood, urine, and in food, feed, and environmental materials.  Ingestion or parenteral inoculation are the primary laboratory hazards.  The importance of aerosol exposure is not known.  Naturally or experimentally infected animals are a potential source of infection for laboratory and animal care personnel, and for other animals.

	Recommended Precautions:  Biosafety Level 2 practices, containment equipment and facilities are recommended for activities with clinical materials and cultures known or potentially containing the agents.  Animal Biosafety Level 2 practices, containment equipment and facilities are recommended for activities with experimentally or naturally infected animals.

Agent:	Salmonella typhi

	Typhoid fever is a demonstrated hazard to laboratory personnel.13,80,153  

	Laboratory Hazards:  The agent may be present in feces, blood, gallbladder (bile) and urine.  Humans are the only known reservoir of infection.  Ingestion or parenteral inoculation of the organism represent the primary laboratory hazards.  The importance of aerosol exposure is not known.

	Recommended Precautions:  Biosafety Level 2 practices, containment equipment and facilities are recommended for all activities utilizing known or potentially infectious clinical materials and cultures.  Biosafety Level 3 practices and procedures are recommended for activities likely to generate aerosols or for activities involving production quantities of organisms.
	Licensed vaccines, which have been shown to protect 70-90% of recipients, may be a valuable adjunct to good safety practices in personnel regularly working with cultures or clinical materials which may contain S. typhi.13

Agent:	Shigella spp.

	Shigellosis is a demonstrated hazard to laboratory personnel with dozens of cases reported in the United States and Great Britain alone.79,80,97,151  While outbreaks have occurred in captive nonhuman primates, humans are the only significant reservoir of infection.  However, experimentally infected guinea pigs, other rodents, and nonhuman primates are also proven sources of infection.

	Laboratory Hazards:  The agent may be present in feces, and rarely, in blood of infected humans or animals.  Ingestion or parenteral inoculation of the agent are the primary laboratory hazards.  The oral 25%-50% infectious dose of S. flexneri for humans is approximately 200 organisms.191  The importance of aerosol exposure is not known.

	Recommended Precautions:  Biosafety Level 2 practices, containment equipment and facilities are recommended for all activities utilizing known or potentially infectious clinical materials or cultures.  Animal Biosafety Level 2 facilities and practices are recommended for activities with experimentally or naturally infected animals.  Vaccines are not available for use in humans.

Agent:	Treponema pallidum

	Syphilis is a documented hazard to laboratory personnel who handle or collect clinical material from cutaneous lesions.  Pike lists 20 cases of laboratory-associated infection.151  Humans are the only known natural reservoir of the agent.  Syphilis has been transmitted to laboratory personnel working with a concentrated suspension of T. pallidum obtained from an experimental rabbit orchitis.74  Hematogenous transfer of syphilis has occurred from the transfusion of a unit of fresh blood obtained from a patient with secondary syphilis.  T. pallidum is present in the circulation during primary and secondary syphilis.  The minimum number (LD50) of T. pallidum organisms needed to infect by subcutaneous injection is 23.114  The concentration of T. pallidum in patients' blood during early syphilis, however, has not been determined. 

	No cases of laboratory animal-associated infections are reported; however, rabbit-adapted strains of T. pallidum (Nichols and possibly others) retain their virulence for humans.

	Laboratory Hazards:  The agent may be present in materials collected from primary and secondary cutaneous and mucosal lesions and in blood.  Accidental parenteral inoculation, contact of mucous membranes or broken skin with infectious clinical materials, and possibly infectious aerosols, are the primary hazards to laboratory personnel.

	Recommended Precautions:  Biosafety Level 2 practices, containment equipment and facilities are recommended for all activities involving the use or manipulation of blood or lesion materials from humans or infected rabbits.  Gloves should be worn when there is a likelihood of direct skin contact with lesion materials.  Periodic serological monitoring should be considered in personnel regularly working with infectious materials.  Vaccines are not available for use in humans.

Agent:	Vibrionic enteritis (Vibrio cholerae, V. para-haemolyticus)

	Vibrionic enteritis due to Vibrio cholerae or Vibrio parahaemolyticus is a documented but rare cause of laboratory-associated illness.153  Naturally and experimentally infected animals are a potential source of infection.

	Laboratory Hazards:  All pathogenic vibrios may occur in feces.  Ingestion of V. cholerae, and ingestion or parenteral inoculation of other vibrios constitute the primary laboratory hazard.  The human oral infecting dose of V. cholerae in healthy non-achlorhydric individuals is approximately 106 organisms.111 The importance of aerosol exposure is not known.  The risk of infection following oral exposure may be increased in achlorhydric individuals.

	Recommended Precautions:  Biosafety Level 2 practices, containment equipment and facilities are recommended for activities with cultures or potentially infectious clinical materials.  Animal Biosafety Level 2 practices, containment equipment and facilities are recommended for activities with naturally or experimentally infected animals.  Although vaccines have been shown to provide partial protection of short duration (3-6 months) to nonimmune individuals in highly endemic areas,13 the routine use of cholera vaccine in laboratory staff is not recommended.

Agent:	Yersinia pestis

	Plague is a proven but rare laboratory hazard.  Four cases have been reported in the United States.17,151 

	Laboratory Hazards:  The agent may be present in bubo fluid, blood, sputum, cerebrospinal fluid (CSF), feces, and urine from humans, depending on the clinical form and stage of the disease.  Primary hazards to laboratory personnel include: direct contact with cultures and infectious materials from humans or rodents; infectious aerosols or droplets generated during the manipulation of cultures, infected tissues, and in the necropsy of rodents; accidental autoinoculation; ingestion; and bites by infected fleas collected from rodents.

	Recommended Precautions:  Biosafety Level 2 practices, containment equipment and facilities are recommended for all activities involving the handling of potentially infectious clinical materials and cultures.  Special care should be taken to avoid the generation of aerosols from infectious materials, and during the necropsy of naturally or experimentally infected rodents.  Gloves should be worn when handling field-collected or infected laboratory rodents, and when there is the likelihood of direct skin contact with infectious materials.  Necropsy of rodents is ideally conducted in a biological safety cabinet.  Although field trials have not been conducted to determine the efficacy of a licensed inactivated vaccine, experience with this product has been favorable.22  Immunization is recommended for personnel working regularly with cultures of Y. pestis or infected rodents.34

	Additional primary containment and personnel precautions, such as those described for Biosafety Level 3, are recommended for activities with high potential for droplet or aerosol production, for work with antibiotic-resistant strains and for activities involving production quantities or concentrations of infectious materials.

•	Rickettsial Agents

Agent:	Coxiella burnetii

	Of the rickettsial agents, Coxiella burnetii probably presents the greatest risk of laboratory infection.  The organism is highly infectious and remarkably resistant to drying and  environmental conditions.190  The infectious dose of virulent, Phase I organisms in laboratory animals has been calculated to be as small as a single organism.  The estimated human ID25-50 (inhalation) for Q fever is 10 organisms.191  Pike's summary indicates that Q fever is the second most commonly reported laboratory-associated infection, with outbreaks involving 15 or more persons recorded in several institutions.141,151  A broad range of domestic and wild mammals are natural hosts for Q fever, and may serve as potential sources of infection for laboratory and animal care personnel.  Exposure to naturally infected, often asymptomatic sheep, and to their birth products, is a documented hazard to personnel.28,175  Although rare, C. burnetii is known to cause chronic infections such as endocarditis or granulomatous hepatitis.  Genetic analyses165 as well as structural analysis of the lipopolysaccharides82 of endocarditis-associated isolates of C. burnetii suggest that specific strains may be associated with endocarditis.  

	Laboratory Hazards:  The necessity of using embryonated eggs or cell culture techniques for the propagation of C. burnetii leads to extensive purification procedures.  Exposure to infectious aerosols or parenteral inoculation are the most likely sources of infection to laboratory and animal care personnel.141  The agent may be present in infected arthropods, and in the blood, urine, feces, milk, and tissues of infected animal or human hosts.  The placenta of infected sheep may contain as many as 109 organisms per gram of tissue195 and milk may contain 105 organisms per gram.  

	Recommended Precautions:  Biosafety Level 2 practices and facilities are recommended for nonpropagative laboratory procedures including serological examinations and staining of impression smears.  Biosafety Level 3 practices and facilities are recommended for activities involving the inoculation, incubation, and harvesting of embryonated eggs or cell cultures, the necropsy of infected animals and the manipulation of infected tissues.  Since infected guinea pigs and other rodents may shed the organisms in urine or feces,151 experimentally infected rodents should be maintained under Animal Biosafety Level 3. 

	Recommended precautions for facilities using sheep as experimental animals are described by Spinelli175 and by Bernard.11  An investigational new Phase I Q fever vaccine (IND) is available from the Special Immunizations Program, U.S. Army Medical Research Institute for Infectious Diseases (USAMRIID), Fort Detrick, Maryland.  The use of this vaccine should be limited to those at high risk of exposure and who have no demonstrated sensitivity to Q fever antigen.  Individuals with valvular heart disease should not work with C. burnetii. 

Agent:	Rickettsia prowazekii, Rickettsia typhi (R. mooseri), Rickettsia tsutsugamushi, Rickettsia canada, and Spotted Fever Group agents of human disease; Rickettsia rickettsii, Rickettsia conorii, Rickettsia akari, Rickettsia australis, Rickettsia siberica. 

	Pike reported 57 cases of laboratory-associated typhus (type not specified), 56 cases of epidemic typhus with 3 deaths, and cases of murine typhus.151  More recently 3 cases of murine typhus were reported from a research facility.26  Two of these 3 cases were associated with handling of infectious materials on the open bench; the third case resulted from an accidental parenteral inoculation.  These 3 cases represented an attack rate of 20% in personnel working with infectious materials.

	Rocky Mountain spotted fever is a documented hazard to laboratory personnel.  Pike151 reported 63 laboratory-associated cases, 11 of which were fatal.  Oster144 reported 9 cases occurring over a 6-year period in one laboratory, which were believed to have been acquired as a result of exposure to infectious aerosols.

	Laboratory Hazards:  Accidental parenteral inoculation and exposure to infectious aerosols are the most likely sources of laboratory-associated infection.89  Successful aerosol transmission of R. rickettsii has been experimentally documented in nonhuman primates.166  Five cases of rickettsial pox recorded by Pike151 were associated with exposure to bites of infected mites. 

	Naturally and experimentally infected mammals, their ectoparasites, and their infected tissues are potential sources of human infection.  The organisms are relatively unstable under ambient environmental conditions.

	Recommended Precautions:  Biosafety Level 2 practices and facilities are recommended for nonpropagative laboratory procedures, including serological and fluorescent antibody procedures, and for the staining of impression smears.  Biosafety Level 3 practices and facilities are recommended for all other manipulations of known or potentially infectious materials including necropsy of experimentally infected animals and trituration of their tissues, and inoculation, incubation, and harvesting of embryonated eggs or tissue cultures.  Animal Biosafety Level 2 practices and facilities are recommended for the holding of experimentally infected mammals other than arthropods.

	Level 3 practices and facilities are recommended for animal studies with arthropods naturally or experimentally infected with rickettsial agents of human disease.

	Because of the proven value of antibiotic therapy in the early stages of infection, it is essential that laboratories working with rickettsiae have an effective system for reporting febrile illnesses in laboratory personnel, medical evaluation of potential cases and, when indicated, institution of appropriate antibiotic therapy.  Vaccines are not currently available for use in humans (see Appendix C).

•	Viral Agents (Other than arboviruses)

Agent:	Hepatitis A Virus, Hepatitis E Virus

	Laboratory-associated infections with hepatitis A or E viruses do not appear to be an important occupational risk among laboratory personnel.  However, the disease is a documented hazard in animal handlers and others working with chimpanzees and other nonhuman primates which are naturally or experimentally infected.153  Hepatitis E virus appears to be less of a risk to personnel than hepatitis A virus, except during pregnancy, when infection can result in severe or fatal disease.  Workers handling other recently captured, susceptible primates (owl monkeys, marmosets) may also be at risk.

	Laboratory Hazards:  The agents may be present in feces, saliva, and blood of infected humans and nonhuman primates.  Ingestion of feces, stool suspensions, and other contaminated materials is the primary hazard to laboratory personnel.  The importance of aerosol exposure has not been demonstrated.  Attenuated or avirulent strains of hepatitis A viruses have been described resulting from serial passage in cell culture.

	Recommended Precautions:  Biosafety Level 2 practices, safety equipment, and facilities are recommended for activities with known or potentially infected feces from humans or nonhuman primates.  Animal Biosafety Level 2 practices and facilities are recommended for activities using naturally or experimentally infected nonhuman primates.  Animal care personnel should wear gloves and take other appropriate precautions to avoid possible fecal-oral exposure.  A licensed inactivated vaccine against hepatitis A is available in Europe; it is available as an investigational vaccine in the U.S., and is recommended for laboratory personnel.  Vaccines against hepatitis E are not available for use in humans.  

Agent:	Hepatitis B Virus, Hepatitis C Virus,	(formerly known as nonA nonB Virus),    Hepatitis D Virus

	Hepatitis B has been one of the most frequently occurring laboratory-associated infections,153 and laboratory workers are recognized as a high risk group for acquiring such infections.170  Individuals who are infected with hepatitis B virus are at risk of infection with hepatitis D (delta) virus, which is defective and requires the presence of hepatitis B virus for replication.

	Hepatitis C infection can occur in the laboratory situation.  The prevalence of antibody to hepatitis C is slightly higher in medical care workers than in the general population.  Epidemiologic evidence indicates that hepatitis C is spread predominantly by the parenteral route.94,128

	Laboratory Hazards:  Hepatitis B virus may be present in blood and blood products of human origin, in urine, semen, cerebrospinal fluid, and saliva.  Parenteral inoculation, droplet exposure of mucous membranes, and contact exposure of broken skin are the primary laboratory hazards.  The virus may be stable in dried blood or blood components for several days.  Attenuated or avirulent strains have not been identified.

	Hepatitis C virus has been detected primarily in blood and serum, less frequently in saliva and rarely or not at all in urine or semen.  It appears to be relatively unstable to storage at room temperature, repeated freezing and thawing, etc.  

	Recommended Precautions:  Biosafety Level 2 practices, containment equipment and facilities are recommended for all activities utilizing known or potentially infectious body fluids and tissues.  Additional primary containment and personnel precautions, such as those described for Biosafety Level 3, may be indicated for activities with potential for droplet or aerosol production and for activities involving production quantities or concentrations of infectious materials.  Animal Biosafety Level 2 practices, containment equipment and facilities are recommended for activities utilizing naturally or experimentally infected chimpanzees or other nonhuman primates.  Gloves should be worn when working with infected animals and when there is the likelihood of skin contact with infectious materials.  Licensed recombinant vaccines against hepatitis B are available and are highly recommended for laboratory personnel.46   Vaccines against hepatitis C and D are not yet available for use in humans.

Agent:	Herpesvirus simiae (B-virus)

	B-virus is a naturally occurring alphaherpesvirus infecting free-living or captive Macaca mulatta, M. fasicularis, and other members of the genus.  It is associated with acute vesicular oral lesions, as well as latent and often recrudescent infection.193  Human infection has been documented in 25 instances, usually with a lethal outcome or serious sequelae from encephalitis.7,92,145

	Although B-virus presents a potential hazard to laboratory personnel working with the agent, laboratory-associated human infections with B-virus have, with rare exceptions, been limited to those having direct contact with macaques.  Primary macaque cell cultures, including commercially-prepared rhesus monkey kidney cells, occasionally are inapparently infected with B-virus and have been implicated in one human case.92

	Sixteen fatal cases of human infections with B-virus have been reported.193

	Laboratory Hazards:  The highest risk of acquiring B-virus from macaques is through the bite of an infected monkey with active lesions.  Contamination of broken skin or mucous membranes with oral, ocular, or genital secretions from animals with lesions, or experiencing clinically silent virus shedding, is also dangerous.  Stability of viral infectivity on cages and other surfaces is not known, but the potential hazard must be recognized.  The importance of aerosol exposure is thought to be minimal.  Attenuated or avirulent strains have not been identified.

	The agent also may be present in thoracic and abdominal viscera and nervous tissues of naturally infected macaques.  These tissues, and the cultures prepared from them, are potential hazards.196

	Recommended Precautions:  Biosafety Level 2 practices and facilities are recommended for all activities involving the use or manipulation of tissues, body fluids, and primary tissue culture materials from macaques.  Additional practices and personnel precautions, such as those detailed for Biosafety Level 3, are recommended for activities involving the use or manipulation of any material known to contain Herpesvirus simiae.  In vitro propagation of the virus for diagnosis may be conducted under the same guidelines, but it would be prudent to confine manipulations of positive cultures which would contain high-titered virus to a Class 3 biosafety cabinet or BSL-4 facility, depending on the judgement of the laboratory director.

	Biosafety Level 4 practices and facilities are recommended for activities involving the propagation and manipulation of production quantities or concentrates of H. simiae.

	The wearing of gloves, masks, and laboratory coats is recommended for all personnel working with non-human primates -- especially macaques and other Old World species -- and for all persons entering animal rooms where non-human primates are housed.  Any macaque colony not known to be free of B-virus infection should be presumed to be naturally infected.  Guidelines are available for safely working with macaques and should be consulted.39,150  Animals with oral lesions suggestive of active B-virus infection should be isolated and handled with extreme caution.  Studies with animals experimentally infected with H. simiae should be conducted at ABSL-3.

	Vaccines are not available for use in humans.  Human to human transmission has only occurred in one case, suggesting that precautions should be taken with vesicle fluids, oral secretions, and conjunctival secretions of infected persons.92

	Antiviral drugs have shown promise in the therapy of rabbits infected with H. simiae, and anecdotal observations suggest this may extend to man.7,92  Because of the seriousness of infection with  this virus, experienced medical personnel should be available for consultation to manage incidents involving exposure to the agent or suspected infections.

Agent:	Human Herpesviruses

	The herpesviruses are ubiquitous human pathogens and are commonly present in a variety of clinical materials submitted for virus isolation.  While few of these viruses are demonstrated causes of clinical laboratory-associated infections, they are primary as well as opportunistic pathogens, especially in immunocompromised hosts.  Herpes simplex viruses 1 and 2 and varicella virus pose some risk via direct contact and/or aerosols; cytomegalovirus and Epstein-Barr virus pose relatively low infection risks to laboratory personnel.  The risk of laboratory infection from herpesviruses 6 and 7 is not known.  Although this diverse group of indigenous viral agents does not meet the criteria for inclusion in agent-specific summary statements (i.e., demonstrated or high potential hazard for laboratory-associated infection; grave consequences should infection occur), the frequency of their presence in clinical materials and their common use in research warrants their inclusion in this publication.

	Laboratory Hazards:  Clinical materials and isolates of herpesviruses may pose a risk of infection following ingestion, accidental parenteral inoculation, droplet exposure of the mucous membranes of the eyes, nose, or mouth, or inhalation of concentrated aerosolized materials.  Clinical specimens containing the more virulent Herpesvirus simiae (B-virus) may be inadvertently submitted for diagnosis of suspected herpes simplex infection.  This virus has also been found in cultures of primary rhesus monkey kidney cells.  Cytomegalovirus may pose a special risk during pregnancy because of potential infection of the fetus.

	Recommended Precautions:  Biosafety Level 2 practices, containment equipment, and facilities are recommended for activities utilizing known or potentially infectious clinical materials or cultures of indigenous viral agents which are associated or identified as a primary pathogen of human disease.  Although there is little evidence that infectious aerosols are a significant source of laboratory-associated infections, it is prudent to avoid the generation of aerosols during the handling of clinical materials or isolates, or during the necropsy of animals.  Primary containment devices (e.g., biological safety cabinets) constitute the basic barrier protecting personnel from exposure to infectious aerosols.

Agent:	Influenza

	Laboratory-associated infections with influenza are not normally documented in the literature, but are known to occur by informal accounts and published reports, particularly when new strains showing antigenic drift or shift are introduced into a laboratory for diagnostic/research purposes.64

	Laboratory animal-associated infections are not reported; however, there is a high possibility of human infection from infected ferrets and vice-versa.

	Laboratory Hazards:  The agent may be present in respiratory tissues or secretions of humans or most infected animals, and in the cloaca of many infected avian species.  The virus may be disseminated in multiple organs in some infected animal species.

	The primary laboratory hazard is inhalation of virus from aerosols generated by infected animals, or by aspirating, dispensing, or mixing virus-infected samples.  Genetic manipulation has the potential for altering the host range, pathogenicity, and antigenic composition of influenza viruses.  There is unknown potential for introducing into man transmissible viruses with novel antigenic composition.

	Recommended Precautions:  Biosafety Level 2 practices and facilities are recommended when receiving and inoculating routine laboratory diagnostic specimens.  Autopsy material should be handled in a biological safety cabinet using Biosafety Level 2 procedures.

	Activities Utilizing Noncontemporary Virus Strains:  Biosafety considerations should take into account the available information about infectiousness and virulence of the strains being used, and the potential for harm to the individual or society in the event that laboratory-acquired infection and subsequent transmission occurs.  Research or production activities utilizing contemporary strains may be safely performed using Biosafety Level 2 containment practices.  Susceptibility to infection with older noncontemporary human strains, with recombinants, or with animal isolates warrant the use of Biosafety Level 2 containment procedures.  However, there is no evidence for laboratory-acquired infection with reference strains A/PR/8/34 and A/WS/33, or its commonly used neurotropic variants.

Agent:	Lymphocytic Choriomeningitis Virus

	Laboratory-associated infections with LCM virus are well- documented in facilities where infections occur in laboratory rodents -- especially mice, hamsters and guinea pigs.14,98,151  Nude and SCID mice may pose a special risk of harboring silent chronic infections.  Cell cultures that inadvertently have become infected represent a potential source of infection and dissemination of the agent.  Natural infections are found in nonhuman primates, including macaques and marmosets (Callitrichid hepatitis virus is a lymphocytic choriomeningitis virus) and may be fatal to marmoset monkeys.  Swine and dogs are less important vectors.

	Laboratory Hazards:  The agent may be present in blood, cerebrospinal fluid, urine, secretions of the nasopharynx, feces and tissues of infected animal hosts and possibly man.  Parenteral inoculation, inhalation, contamination of mucous membranes or broken skin with infectious tissues or fluids from infected animals, are common hazards.  Aerosol transmission is well documented.14  The virus may pose a special risk during pregnancy because of potential infection of the fetus.

	Recommended Precautions:  Biosafety Level 2 practices and facilities are suitable for activities utilizing known or potentially infectious body fluids, and for tissue culture passage of laboratory-adapted, mouse brain-passaged strains.  Animal Biosafety Level 2 practices and facilities are suitable for studies in adult mice with mouse brain-passaged strains.  However, additional primary containment and personnel precautions, such as those described for Biosafety Level 3, are indicated for activities with high potential for aerosol production, or involving production quantities or concentrations of infectious materials; and for manipulation of infected transplantable tumors, field isolates and clinical materials from human cases.  Animal Biosafety Level 3 practices and facilities are recommended for work with infected hamsters.  Vaccines are not available for use in humans.98

Agent:	Poliovirus

	Laboratory-associated infections with polioviruses are uncommon and have been limited to unvaccinated laboratory personnel working directly with the agent.151   Laboratory animal-associated infections have not been reported;23 however, naturally or experimentally infected nonhuman primates could provide a source of infection to exposed unvaccinated persons.  Transgenic mice expressing the human receptor for polioviruses can be infected with virulent polioviruses and are a potential source of human infection.

	Laboratory Hazards:  The agent is present in the feces and in throat secretions of infected persons.  Ingestion or parenteral inoculation of infectious tissues or fluids by non-immunized personnel are the primary hazards in the laboratory.   The importance of aerosol exposure is not known; it has not been reported as a hazard.  Laboratory exposures pose negligible risk to appropriately immunized persons.

	Recommended Precautions:  Biosafety Level 2 practices and facilities are recommended for all activities utilizing known or potentially infectious culture fluids and clinical materials involving known or suspected wild-type strains.  All laboratory personnel working directly with the agent must have documented polio vaccination or demonstrated serologic evidence of immunity to all three poliovirus types.33  Animal Biosafety Level 2 practices and facilities are recommended for studies of virulent viruses in animals.  Unless there are strong scientific reasons for working with virulent polioviruses (which have been eradicated from the United States), laboratories should use the attenuated Sabin oral poliovirus vaccine strains.  These pose no significant risk to immunized laboratory personnel.
Agent:	Poxviruses

	Sporadic cases of laboratory-associated infections with pox viruses (smallpox, vaccinia, yaba, tanapox) have been reported.151  Epidemiological evidence suggests that transmission to humans of monkeypox virus from nonhuman primates or rodents to humans may have occurred in nature, but not in the laboratory setting.  Naturally or experimentally infected laboratory animals are a potential source of infection to exposed unvaccinated laboratory personnel.  Genetically engineered recombinant vaccinia viruses pose an additional potential risk to laboratory personnel, through direct contact or contact with clinical materials from infected volunteers or animals.

	Laboratory Hazards:  The agents may be present in lesion fluids or crusts, respiratory secretions, or tissues of infected hosts.  Ingestion, parenteral inoculation, and droplet or aerosol exposure of mucous membranes or broken skin with infectious fluids or tissues, are the primary hazards to laboratory and animal care personnel.  Some poxviruses are stable at ambient temperature when dried and may be transmitted by fomites.

	Recommended Precautions:  The possession and use of variola viruses is restricted to the World Health Organization Collaborating Center for Smallpox and Other Poxvirus Infections, located at the Centers for Disease Control and Prevention, Atlanta, Georgia.  Biosafety Level 2 practices and facilities are recommended for all activities involving the use or manipulation of poxviruses, other than variola, that pose an infection hazard to humans.  All persons working in or entering laboratory or animal care areas where activities with vaccinia, monkey pox, or cow pox viruses are being conducted should have documented evidence of satisfactory vaccination within the preceding ten years.31,52  Activities with vaccinia, cow pox, or monkey pox viruses, in quantities or concentrations greater than those present in diagnostic cultures, may also be conducted at Biosafety Level 2 by immunized personnel, provided that all manipulations of viable materials are conducted in Class I or II biological safety cabinets 

or other primary containment equipment.  Immunosuppressed individuals are at greater risk of severe disease if infected with a poxvirus.52

Agent:	Rabies Virus

	Laboratory-associated infections are extremely rare.  Two have been documented.  Both resulted from presumed exposure to high titered infectious aerosols generated in a vaccine production facility201 and a research facility,25 respectively.  Naturally or experimentally infected animals, their tissues, and their excretions are a potential source of exposure for laboratory and animal care personnel.

	Laboratory Hazards:  The agent may be present in all tissues of infected animals.  Highest titers are present in CNS tissue, salivary glands, and saliva.  Accidental parenteral inoculation, cuts, or sticks with contaminated laboratory equipment, bites by infected animals, and exposure of mucous membranes or broken skin to infectious tissue or fluids, are the most likely sources for exposure of laboratory and animal care personnel.  Infectious aerosols have not been a demonstrated hazard to personnel working with clinical materials and conducting diagnostic examinations.  Fixed and attenuated strains of virus are presumed to be less hazardous, but the only two recorded cases of laboratory associated rabies resulted from exposure to a fixed Challenge Virus Standard (CVS) and an attenuated strain derived from SAD (Street Alabama Dufferin) strain, respectively.25,201

	Recommended Precautions:  Biosafety Level 2 practices and facilities are recommended for all activities utilizing known or potentially infectious materials.  Immunization is recommended for all individuals prior to working with rabies virus or infected animals, or engaging in diagnostic, production, or research activities with rabies virus.  Immunization is also recommended for all individuals entering or working in the same room where rabies virus or infected animals are used.  While it is not always feasible to open the skull or remove the brain of an infected animal within a biological safety cabinet, it is pertinent to wear heavy protective gloves to avoid cuts or sticks from cutting instruments or bone fragments, and to wear a face shield to protect the mucous membranes of the eyes, nose, and mouth from exposure to infectious droplets or tissue fragments.  If a Stryker saw is used to open the skull, avoid contacting the brain with the blade of the saw.  Additional primary containment and personnel precautions, such as those described for Biosafety Level 3, may be indicated for activities with a high potential for droplet or aerosol production, and for activities involving production quantities or concentrations of infectious materials.

Agent:	Retroviruses, including Human and Simian Immunodeficiency Viruses (HIV and SIV) 

	Data on occupational HIV transmission in laboratory workers are collected through two CDC-supported national surveillance systems: surveillance for 1) AIDS and 2) HIV-infected persons who may have acquired their infection through occupational exposures.  For surveillance purposes, laboratory workers are defined as those persons, including students and trainees, who have worked in a clinical or HIV laboratory setting at anytime since 1978.  Persons reported from these two systems are classified as cases of either documented or possible occupational transmission.  Those classified as documented occupational transmission had evidence of HIV seroconversion (a negative HIV-antibody test at the time of the exposure which converted to positive) following a discrete percutaneous or mucocutaneous occupational exposure to blood, body fluids, or other clinical or laboratory specimens.  Those persons classified as possible occupational transmission do not have behavioral or transfusion risks for HIV infection which could be identified during follow-up investigation;  each reported past percutaneous or mucocutaneous occupational exposures to blood, body fluids, or laboratory specimens, but seroconversion to HIV was not documented.

	As of September 30, 1992, CDC had reports of 12 (11 clinical and 1 nonclinical) laboratory workers in the United States with documented occupational transmission and 13 (12 clinical and 1 nonclinical) classified as possible occupational transmission.55

	Among those with documented occupational transmission, 8 had percutaneous exposure, 3 had mucocutaneous exposure, and 1 had both percutaneous and mucocutaneous exposures.  Eleven were exposed to HIV-infected blood and one to concentrated live HIV.  The procedure most often associated with transmission was phlebotomy.  Three of these workers have developed AIDS.

	Of the 13 laboratory workers classified as possible occupational transmission, 9 have developed AIDS.

	In 1992, two workers were reported to have developed antibodies to simian immunodeficiency virus (SIV) following exposures in different laboratories.  One was associated with a needle stick which occurred while the worker was manipulating a blood-contaminated needle after bleeding an SIV-infected macaque monkey.103  The other involved a laboratory worker who handled macaque SIV-infected blood specimens without gloves.  Though no specific incident was recalled, this worker had dermatitis on the forearms and hands while working with the infected blood specimens.53  As of October 1992 neither of the two workers had developed any illness.

	Laboratory Hazards:   HIV has been isolated from blood, semen, saliva, tears, urine, cerebrospinal fluid, amniotic fluid, breast milk, cervical secretion, and tissue of infected persons and experimentally infected nonhuman primates.167  CDC has recommended that blood and body fluid precautions be used consistently when handling any blood-contaminated specimens.43,45  This approach, referred to as "universal precautions", precludes the need to identify clinical specimens obtained from HIV+ patients or to speculate as to the HIV status of a specimen.  

	Although the risk of occupationally acquired HIV is primarily through exposure to infected blood, it is also prudent to wear gloves when manipulating other body fluids such as feces, saliva, urine, tears, sweat, vomitus and human breast milk.  This reduces the potential for exposure to other microorganisms that may cause other types of infections.

	In the laboratory, virus should be presumed to be present in all blood or clinical specimens contaminated with blood, in any unfixed tissue or organ (other than intact skin) from a human (living or dead), in HIV cultures, in all materials derived from HIV cultures, and in/on all equipment and devices coming into direct contact with any of these materials.

	SIV has been isolated from blood, cerebrospinal fluid, and a variety of tissues of infected nonhuman primates.  Limited data exist on the concentration of virus in semen, saliva, cervical secretions, urine, breast milk, and amniotic fluid.  In the laboratory, virus should be presumed to be present in all SIV cultures, in animals experimentally infected or inoculated with SIV, in all materials derived from HIV or SIV cultures, and in/on all equipment and devices coming into direct contact with any of these materials.44

	In the laboratory, the skin (especially when scratches, cuts, abrasions, dermatitis, or other lesions are present) and mucous membranes of the eye, nose, and mouth should be considered as potential pathways for entry of these retroviruses.  Whether infection can occur via the respiratory tract is unknown.  Needles, sharp instruments, broken glass, and other sharp objects must be carefully handled and properly discarded.  Care must be taken to avoid spilling and splashing infected cell-culture liquid and other virus-containing or potentially-infected materials.

Recommended Precautions:
	In addition to these recommended precautions, persons working with HIV, SIV, or other bloodborne pathogens should consult the OSHA Bloodborne Pathogen Standard.187  Questions related to interpretation of this Standard should be directed to Federal, regional or state OSHA offices.

1.	BSL-2 standard and special practices, containment equipment and facilities are recommended for activities involving all blood-contaminated clinical specimens, body fluids and tissues from all humans or from HIV- or SIV-infected or inoculated laboratory animals.

2.	Activities such as producing research-laboratory-scale quantities of HIV or SIV, manipulating concentrated virus preparations, and conducting procedures that may produce droplets or aerosols, are performed in a BSL-2 facility, but using the additional practices and containment equipment recommended for BSL-3.

3.	Activities involving industrial-scale volumes or preparation of concentrated HIV or SIV are conducted in a BSL-3 facility, using BSL-3 practices and containment equipment.

4.	Nonhuman primates or other animals infected with HIV or SIV are housed in ABSL-2 facilities using ABSL-2 special practices and containment equipment.

Additional Comments:
	
1.	There is no evidence that laboratory clothing poses a risk for retrovirus transmission; however, clothing that becomes contaminated with HIV or SIV preparations should be decontaminated before being laundered or discarded. Laboratory personnel must remove laboratory clothing before going to non-laboratory areas.

2.	Work surfaces are decontaminated with an appropriate chemical germicide after procedures are completed, when surfaces are overtly contaminated, and at the end of each work day.  Many commercially available chemical disinfectants70,116,158,164,188 can be used for decontaminating laboratory work surfaces and some laboratory instruments, for spot cleaning of contaminated laboratory clothing, and for spills of infectious materials. Prompt decontamination of spills should be standard practice.

3.	Human serum from any source that is used as a control or reagent in a test procedure should be handled at BSL-2.

4.	It is recommended that all institutions establish written policies regarding the management of laboratory exposure to HIV and SIV in conjunction with applicable federal, state and local laws.  Such policies should consider confidentiality, consent for testing, administration of appropriate prophylactic drug therapy,48 counseling, and other related issues.  If a laboratory worker has a parenteral or mucous-membrane exposure to blood, body fluid, or viral-culture material, the source material should be identified and, if possible, tested for the presence of virus. If the source material is positive for HIV antibody, virus, or antigen, or is not available for examination, the worker should be counseled regarding the risk of infection and should be evaluated clinically and serologically for evidence of HIV infection. The worker should be advised to report and  seek medical evaluation of any acute febrile illness that occurs within 12 weeks after the exposure.40  Such an illness -- particularly one characterized by fever, rash, or lymphadenopathy -- may indicate recent HIV infection. If seronegative, the worker should be retested 6 weeks after the exposure and periodically thereafter (i.e., at 12 weeks and 6, 9 and 12 months after exposure). During this follow-up period exposed workers should be counseled to follow Public Health Service recommendations for preventing transmission of HIV.37,40,41,48,120 

5.	Other primary and opportunistic pathogenic agents may be present in the body fluids and tissues of persons infected with HIV.  Laboratory workers should follow accepted biosafety practices to ensure maximum protection against inadvertent laboratory exposure to agents that may also be present in clinical specimens or in specimens obtained from non-human primates.36,38,42
	
	Research involving other human (i.e., human T-lymphotrophic virus types I and II) and simian retroviruses occurs in many laboratories.  Transmission of such viruses has not been reported in the laboratory setting.  The precautions outlined above are sufficient while working with these agents.

	Between 1989 and 1992, 69 persons with CD4+ T-lymphocyte depletion, but without evident HIV infection, were identified in the United States.  This condition has been provisionally termed "Idiopathic CD4+ T-lymphocytopenia (ICL).  To date, investigations of persons with idiopathic CD4+ T-cell depletion indicate that ICL is rare, that these findings may represent various disorders, and in some cases, normal or transient variations in CD4+ T-lymphocyte counts.  No epidemiologic or laboratory evidence of a transmissible agent of immunodeficiency has been found as of October 1992.172a

Agent:	Transmissible Spongiform Encephalopathies (Creutzfeldt-Jakob, kuru and related agents)

	Laboratory-associated infections with the transmissible spongiform encephalopathies (prion diseases) have not been documented.  However, there is evidence that Creutzfeldt-Jakob disease (CJD) has been transmitted iatrogenically to patients by corneal transplants, dura mater grafts and growth hormone extracted from human pituitary glands, and by exposure to contaminated electroencephalographic electrodes.99  Infection is always fatal.  There is no known nonhuman reservoir for CJD or kuru.  Nonhuman primates and other laboratory animals have been infected by inoculation, but there is no evidence of secondary transmission.  Scrapie of sheep and goats, bovine spongiform encephalopathy and mink encephalopathy are transmissible spongiform encephalopathies of animals that are similar to the human transmissible diseases.  However, there is no evidence that the animal diseases can be transmitted to man.

	Laboratory Hazards:  High titers of a transmissible agent have been demonstrated in the brain and spinal cord of persons with kuru.  In persons with Creutzfeldt-Jakob disease and its Gerstmann-Sträussler-Schenker Syndrome variants, a similar transmissible agent has been demonstrated in the brain, spleen, liver, lymph nodes, lungs, spinal cord, kidneys, cornea and lens, and in spinal fluid and blood.  Accidental parenteral inoculation, especially of nerve tissues, including formalin-fixed specimens, is extremely hazardous.  Although non-nerve tissues are less often infectious, all tissues of humans and animals infected with these agents should be considered potentially hazardous.  The risk of infection from aerosols, droplets, and exposure to intact skin, gastric and mucous membranes is not known; however, there is no evidence of contact or aerosol transmission.  These agents are characterized by extreme resistance to conventional inactivation procedures including irradiation, boiling, dry heat and chemicals (formalin, betapropiolactone, alcohols); however, they are inactivated by 1 N NaOH, sodium hypochlorite (_2% free chlorine concentration) and steam autoclaving at 134oC for 1 hour.

	Recommended Precautions:  Biosafety Level 2 practices and facilities are recommended for all activities utilizing known or potentially infectious tissues and fluids from naturally-infected humans and from experimentally infected animals.  Extreme care must be taken to avoid accidental autoinoculation, or other traumatic parenteral inoculations of infectious tissues and fluids.76  Although there is no evidence to suggest that aerosol transmission occurs in the natural disease, it is prudent to avoid the generation of aerosols or droplets during the manipulation of tissues or fluids, and during the necropsy of experimental animals.  It is further strongly recommended that gloves be worn for activities that provide the opportunity for skin contact with infectious tissues and fluids.  Formaldehyde-fixed and paraffin-embedded tissues, especially of the brain, remain infectious.  It is recommended that formalin-fixed tissues from suspected cases of transmissible encephalopathy be immersed in 96% formic acid for 30 minutes before histopathologic processing.15  Vaccines are not available for use in humans.51

Agent:	Vesicular Stomatitis Virus 

	A number of laboratory-associated infections with indigenous strains of VSV have been reported.178  Laboratory activities with such strains present two different levels of risk to laboratory personnel and are related, at least in part, to the passage history of the strains utilized.  Activities utilizing infected livestock, their infected tissues, and virulent isolates from these sources are a demonstrated hazard to laboratory and animal care personnel.85,148  Rates of seroconversion and clinical illness in personnel working with these materials are high.148  Similar risks may be associated with exotic strains such as Piry.178

	In contrast, anecdotal information indicates that activities with less virulent laboratory-adapted strains (e.g., Indiana, San Juan and Glascow) are rarely associated with seroconversion or illness.  Such strains are commonly used by molecular biologists, often in large volumes and high concentrations, under conditions of minimal or no primary containment.  Some strains of VSV are considered restricted organisms by USDAregulations(9CFR 122.2).  Experimentally infected mice have not been a documented source of human infection.

	Laboratory Hazards: The agent may be present in vesicular fluid, tissues, and blood of infected animals and in blood and throat secretions of infected humans.  Exposure to infectious aerosols, infected droplets, direct skin and mucous membrane contact with infectious tissues and fluids, and accidental autoinoculation, are the primary laboratory hazards associated with virulent isolates.  Accidental parenteral inoculation and exposure to infectious aerosols represent potential risks to personnel working with less virulent laboratory-adapted strains.

	Recommended Precautions:  Biosafety Level 3 practices and facilities are recommended for activities involving the use or manipulation of infected tissues and virulent isolates from naturally or experimentally infected livestock.  Gloves and respiratory protection are recommended for the necropsy and handling of 157 infected animals.  Biosafety Level 2 practices and facilities are recommended for activities utilizing laboratory-adapted strains of demonstrated low virulence.  Vaccines are not available for use in humans.

 Agent:	Arboviruses

Arboviruses Assigned to Biosafety Level 2

	The American Committee on Arthropod-Borne Viruses (ACAV) registered 535 arboviruses as of December 1991.  In 1979, the ACAV's Subcommittee on Arbovirus Laboratory Safety (SALS) categorized each of the 424 viruses then registered in the Catalogue of Arboviruses and Certain other Viruses of Vertebrates96  into 1 of 4 recommended practices, safety equipment, and facilities described in this publication as Biosafety Levels 1-4.178 Since 1980, SALS has periodically updated the 1980 publication by providing a supplemental listing and recommended levels of practice and containment for arboviruses registered since 1979.  SALS categorizations were based on risk assessments from information provided by a worldwide survey of 585 laboratories working with arboviruses.
SALS recommended that work with the majority of these agents should be conducted at the equivalent of Biosafety Level 2, Table A. SALS also recognizes five commonly used vaccine strains, for which attenuation is firmly established, which may be handled safely at BSL 2,  provided that personnel working with these vaccine strains are immunized, Table B.  SALS has classified all registered viruses for which insufficient laboratory experience exists as BSL 3, Table C, and reevaluates the classification whenever additional experience is reported.

	The viruses classified as BSL 2 are listed alphabetically in Table A on pages 126 through 129, and include the following agents which are reported to cause laboratory-associated infections.86,151,178

Virus	Cases

Vesicular stomatitis	46
Colorado tick fever	16
Dengue	11
Pinchinde	17
Western equine encephalomyelitis	7(2deaths)
Rio Bravo	7
Kunjin	6
Catu	5
Caraparu	5
Ross River	5
Bunyamwera	4
Eastern equine encephalomyelitis	4
Zika	4
Apeu	2
Marituba	2
Tacaribe	2
Muructucu	1
O'nyong nyong	1
Modoc	1
Oriboca	1
Ossa	1
Keystone	1
Bebaru	1
Bluetongue	1

	The result of the SALS survey clearly indicate that the suspected source of the laboratory-associated infections listed above was other than exposure to infectious aerosols.  Recommendations that work with the 341 arboviruses, listed in Table A, should be conducted at Biosafety Level 2 was based on the existence of adequate historical laboratory experience to assess risks for the virus which indicate that (a) no overt laboratory-associated infections are reported or (b) infections resulted from exposures other than to infectious aerosols or (c) if disease from aerosol exposure is  documented, it is uncommon.

	Laboratory Hazards:  Agents listed in this group may be present in blood, CSF, central nervous system and other tissues, and infected arthropods, depending on the agent and the stage of infection.  While the primary laboratory hazards are accidental parenteral inoculation, contact of the virus with broken skin or mucous membranes, and bites of infected laboratory rodents or arthropods, infectious aerosols may also be a potential source of infection.
	Recommended Precautions:  Biosafety Level 2 practices, safety equipment, and facilities are recommended for activities with potential infectious clinical materials and arthropods and for manipulations of infected tissue cultures, embryonated eggs, and rodents.  Infection of newly hatched chickens with eastern and western equine encephalomyelitis viruses is especially hazardous and should be undertaken under Biosafety Level 3 conditions by immunized personnel.  Investigational vaccines (IND) against eastern equine encephalomyelitis and western equine encephalomyelitis viruses are available through the Centers for Disease Control and Prevention and the U.S. Army Medical Research Institute for Infectious Diseases, (USAMRIID) Fort Detrick, Maryland.  The use of these vaccines is recommended for personnel who work directly and regularly with these two agents in the laboratory.  Western equine encephalomyelitis immune globulin (human) is also available from the Centers for Disease Control and Prevention.  The efficacy of this product has not been established.

	Prior to 1988, 12 laboratory-acquired dengue infections had been reported.  However, from 1988 through 1991, four additional cases have been documented.  In all four cases, proper protective gear (long sleeve lab gowns tying in back, gloves, masks, safety glasses) were not worn; and, in three instances, containment of potential aerosols in a laminar flow biosafety cabinet was ignored.  These aerosols or infected fluids most likely produced contamination of broken, unprotected skin.  An additional factor in these cases was work with highly concentrated amounts of virus.  Safe manipulations of dengue viruses in the laboratory (particularly in concentrated preparations) requires strict adherence to Biosafety Level 2 recommendations.

Table A. Arboviruses and Arenaviruses Assigned to Biosafety Level 2

Acado		
Acara		
Aguacate	
Alfuy		
Almpiwar	
Amapari	
Ananindeua	
Anhanga	
Anhembi	
Anopheles A	
Anopheles B	
Apeu		
Apoi		
Aride		
Arkonam	
Aroa		
Aruac		
Arumowot	
Aura		
Avalon	
Abras		
Abu Hammad	
Aabahoyo	
Bagaza	
Bahig		
Bakau		
Baku		
Bandia	
Bangoran	
Bangui	
Banzi		
Barmah 	Forest	
Barur		
Batai		
Batama	
Bauline	
Bebaru	
Belmont	
Benevides	
Benfica	
Bertioga	
Bimiti	
Birao		
Bluetongue	
Boraceia	
Botambi	
Boteke	
Bouboui	
Bujaru	
Bunyamwera	
Bunyip	
Burg E Arab	
Bushbush	
Bussuquara	
Buttonwillow
Bwamba	
Cacao		
Cache Valley
Caimito	
California 	enc.	
Calovo	
Candiru	
Cape Wrath	
Capim		
Caraparu	
Carey Island
Catu		
Chaco		
Chagres
Chandipura	
Changuinola	
Charleville	
Chenuda	
Chilibre	
Chobar gorge
Clo Mor	
Colorado 	tick fever
Corriparta	
Cotia		
Cowbone 	Ridge	
Csiro 	Village	
Cuiaba-	D'aguilar	
Dakar Bat	
Dengue-1	
Dengue-2	
Dengue-3	
Dengue-4	

Dera Ghazi 	Khan	
East. equine 	enc.(d)
Edge Hill	
Entebbe Bat	
Ep. Hem. 	Disease	
Erve		
Eubenangee	
Eyach		
Flanders	
Fort Morgan	
Frijoles	
Gamboa	
Gan Gan	
Gomoka	
Gossas	
Grand Arbaud
Great Island
Guajara	
Guama		
Guaratuba	
Guaroa	
Gumbo Limbo	
Hart Park	
Hazara	
Highlands J	
Huacho	
Hughes	
Icoaraci	
Ieri		
Ilesha	
Ilheus	
Ingwavuma	
Inkoo		
Ippy		
Irituia	
Isfahan	
Itaporanga	
Itaqui	
Jamestown 	Canyon	
Japanaut	
Jerry Slough
Johnston 	Atoll	
Joinjakaka	
Juan Diaz	
Jugra		
Jurona	
Jutiapa	
Kadam		
Kaeng Khoi	
Kaikalur	
Kaisodi	
Kamese	
Kammavan 	pettai	
Kannaman 	galam	
Kao Shuan	
Karimabad	
Karshi	
Kasba		
Kemerovo	
Kern Canyon	
Ketapang	
Keterah	
Keuraliba	
Keystone	
Kismayo	
Klamath	
Kokobera	
Kolongo	
Koongol	
Kotonkan	
Kowanyama	
Kunjin	
Kununurra	
Kwatta	
La Crosse	
La Joya	
Lagos Bat	
Landjia	
Langat	
Lanjan	
Las Maloyas	
Latino	
Le Dantec	
Lebombo	
Lednice	
Lipovnik	
Lokern	
Lone Star	
Lukuni	
M'poko	
Madrid	
Maguari	
Mahogany 	Hammock	
Main Drain	
Malakal	
Manawa	
Manzanilla	
Mapputta	
Maprik	
Marco		
Marituba	
Marrakai	
Matariya	
Matruh	
Matucare	
Melao		
Mermet	
Minatitlan	
Minnal	
Mirim		
Mitchell 	River	
Modoc		
Moju		
Mono Lake	
Mont. myotis 	leuk.
Moriche	
Mosqueiro	
Mossuril	
Mount Elgon BatMurutucu	
Mykines	
Navarro	
Nepuyo	
Ngaingan	
Nique		
Nkolbisson	
Nola		
Ntaya		
Nugget	
Nyamanini	
Nyando	
O'nyong-	nyong`	
Okhotskiy	
Okola		
Olifantsvlei
Oriboca	
Ossa		
Pacora	
Pacui		
Pahayokee	
Palyam	
Parana	
Pata		
Pathum Thani
Patois	
Phnom-Penh 	Bat	
Pichinde	
Pixuna	
Pongola	
Ponteves	
Precarious 	Point	
Pretoria	
Prospect 	Hill	
Puchong	
Punta 	Salinas	
Punta Toro	
Qalyub	
Quaranfil	
Restan	
Rio Bravo	
Rio Grande	
Ross River	
Royal Farm	
Sabo		
Saboya	
Saint Floris
Sakhalin	
Salehabad	
San angelo	
Sandfly f. 	(Naples)	
Sandfly f. 	(Sicilian)
Sandjimba	
Sango		
Sathuperi	
Sawgrass	
Sebokele	
Seletar	
Sembalam	
Serra do 	Navio
Shamonda	
Shark River	
Shuni		
Silverwater	
Simbu		
Simian hem. 	fever
Sindbis
Sixgun City	
Snowshoe Hare
Sokuluk	
Soldado	
Sororoca	
Stratford
Sunday Canyon
Tacaiuma	
Tacaribe	
Taggert	
Tahyna	
Tamiami	
Tanga		
Tanjong Rabo
Tataguine	
Tehran
Tembe		
Tembusu	
Tensaw	
Tete
Tettnang
Thimiri
Thottapal
	ayam
Tibrogargan
Timbo
Timboteua
Tindholmur
Toscana	
Toure		
Tribec	
Triniti	
Trivittatus	
Trubanaman	
Tsuruse	
Turlock	
Tyuleniy	
Uganda S	
Umatilla	
Umbre		
Una		
Upolu		
Urucuri	
Usutu		
Uukuniemi	
Vellore	
Venkatapuram
Vinces	
Virgin River
VS-Indiana	
VS-New 	Jersey	
Wad Medani
Wallal	
Wanowrie	
Warrego	
West. equine 	enc.(d)	
Whataroa	
Witwaters-	rand	
Wonga		
Wongorr	
Wyeomyia	
Yaquinea 	Head	
Yata		
Yogue		
Zaliv		
Terpeniya	
Zegla		
Zika		
Zingilamo	
Zirqa

Table B.	Vaccine Strains of BSL 3/4 Viruses Which May be Handled at BSL 2

	Virus					Vaccine Strain

	Chikungunya					131/25

	Junin						Candid #1

	Rift Valley fever20			MP-12

	Venezuelan equine 			TC-83	encephalomyelitis	

	Yellow fever				17-D

Arboviruses and Arenaviruses Assigned to Biosafety Level 3

	SALS has recommended that work with the 171 arboviruses included in the two alphabetical listings on pages 126 and 132 should be conducted at the equivalent of Biosafety Level 3 practices, safety equipment and facilities.  These recommendations are based on the following criteria: for Table C (pages 132-133), SALS considered the laboratory experience inadequate to assess risk, regardless of the available information regarding disease severity. For Table D (page 134), SALS recorded overt laboratory-associated infections with these agents which occurred by the aerosol route if protective vaccines were not used or were unavailable, and that the natural disease in humans is potentially severe, life threatening, or causes residual damage. Arboviruses were also classified BSL 3 if they cause diseases in domestic animals in countries outside the USA.  Laboratory or laboratory animal-associated infections have been reported with the following BSL agents:86,151,178

Virus							Cases (SALS)

Venezuelan equine encephalomyelitis	150 deaths
Rift Valley fever	47 (1 death)
Chikungunya	39
Yellow fever	38 (8 deaths)
Japanese encephalitis	22
Louping ill	22
Virus	Cases (SALS)

West Nile		18
Lymphocytic choriomeningitis		15
Orungo		13
Pery		13
Wesselsbron		13
Mucambo		10
Oropouche		7
Germiston		6
Bhanja		6
Hantaan		6
Mayaro		5
Spondweni		4
Murray Valley encephalitis		3
Semliki Forest		3 (1 death)
Powassan		2
Dugbe		2
Issyk-kul		1
Koutango		1

	Large quantities and high concentrations of Semliki Forest virus are commonly used or manipulated by molecular biologists under conditions of moderate or low containment.  Although antibodies have been demonstrated in individuals working with this virus the first overt (and fatal) laboratory-associated infection with this virus was reported in 1979.198  Because the outcome of this infection may have been influenced by a compromised host, an unusual route of exposure or high dosage, or a mutated strain of the virus, this case and its outcome are not typical. More recently, SFV was associated with an outbreak of febrile illness among European soldiers stationed in Bangui.118 The route of exposure was not determined in the fatal laboratory infection; for the natural infections, mosquitoes were the probable vector. SALS continues to classify SFV as a BL 3 virus, with the caveat that most activities with this virus can be safety conducted at Biosafety Level 2.

	Some viruses (e.g., Akabane, Israel turkey meningoencepha-litis) are listed in Level 3, not because they pose a threat to human health, but because they are exotic diseases of domestic livestock or poultry.

	Laboratory Hazards:  The agents listed in this group may be present in blood, cerebrospinal fluid, urine and exudates depending on the specific agent and stage of disease.  The primary laboratory hazards are exposure to aerosols of infectious solutions and animal bedding, accidental parenteral inoculation, and broken skin contact.  Some of these agents (e.g., VEE) may be relatively stable in dried blood or exudates.  Attenuated vaccine strains for a number of these agents are listed in Table B. 

	Recommended Precautions: Biosafety Level 3 practices, safety equipment, and facilities are recommended for activities using potentially infectious clinical materials and infected tissue cultures, animals, or arthropods.

	A licensed attenuated live virus is available for immunization against yellow fever and is recommended for all personnel who work with this agent or with infected animals, and those who enter rooms where the agents or infected animals are present.  An investigational vaccine (IND) available for immunization against Venezuelan equine encephalomyelitis is recommended for all personnel working with VEE (and the related Everglades, Mucambo, Tonate, and Cabassou viruses), infected animals, or entering rooms where these agents or infected animals are present.  Likewise, investigational vaccines for Rift Valley fever and Junin viruses are available from USAMRIID.  Work with Hantaan (Korean hemorrhagic fever) virus and related viruses (Puumala and Seoul) in rats, voles, and other laboratory rodents should be conducted with special caution, because of the extreme hazard of aerosol infection.

Table C.	Arboviruses and Certain Other Viruses Assigned to Biosafety Level 3 
(on the basis of insufficient experience)

Adelaide River	
Agua Preta		
Alenquer		
Almeirim		
Altamira		
Andasibe		
Antequera		
Araguari		
Aransas Bay		
Arbia			
Arboledas		
Babanki		
Batken		
Belem			
Berrimah		
Bimbo			
Bobaya		
Bobia			
Bozo			
Buenaventura	
Cabassue (c,d)	
Cacipacore		
Calchaqui		
Cananeia		
Caninde		
Chim			
Coastal Plains	
Connecticut		
Corfou		
Dabakala		
Douglas		
Enseada		
Estero Real		
Fomede		
Forecariah		
Fort Sherman	
Gabek Forest	
Gadgets Gully	
Garba			
Gordil		
Gray Lodge		
Gurupi		
Iaco			
Ibaraki		
Ife			
Ingangapi		
Inini			
Issyk-Kul		
Itaituba		
Itimirim		
Itupiranga		
Jacareacanga	
Jamanxi		
Jari			
Kedougou		
Khasan		
Kindia		
Kyzylagach		
Lake Clarendon	
Llano Seco		
Macaua		
Mapuera		
Mboke			
Meaban		
Mojui Dos Compos	
Monte Dourado	
Munguba		
Naranjal		
Nariva		
Nasoule		
Ndelle		
New Minto		
Ngari			
Ngoupe		
Nodamura		
Northway		
Odrenisrou		
Omo			
Oriximina		
Ouango		
Oubangui		
Oubi			
Ourem			
Palestina		
Para			
Paramushir		
Paroo River		
Perinet		
Petevo		
Picola		
Playas		
Pueblo Viejo	
Purus			
Radi			
Razdan		
Resistencia		
Rochambeau		
Salanga		
San Juan		
Santa Rosa		
Santarem		
Saraca		
Saumarez Reef	
Sedlec		
Sena Madureira	
Sepik			
Shokwe		
Slovakia		
Somone		
Spipur		
Tai			
Tamdy			
Telok Forest	
Termeil		
Thiafora		
Tilligerry		
Tinaroo		
Tlacotalpan		
Tonate (c,d)	
Ttinga		
Xiburema		
Yacaaba		
Yaounde		
Yoka			
Yug Bogkanovac
c.  SALS recommends that work with this agent should be conducted only in Biosafety Level 3 facilities which provide for HEPA filtration of all exhaust air prior to discharge from the laboratory.
d.  A vaccine is available and is recommended for all persons working with this agent.

Table D.	Arboviruses and Certain Other Viruses Assigned to Biosafety Level 3

Aino
Akabane
Bhanja
Chikungunya (c,d)
Cocal
Dhori
Dugbe
Everglades (c,d)
Flexal
Germiston (c)
Getah
Hantaan
Israel Turkey mening.
Japanese enc.
Junin (c,d)
Kairi
Kimberley
Koutango
Louping Ill (a,c)
Mayaro
Middelburg
Mobala
Mopeia (e) 
Mucambo (c,d)
Murray Valley enc.
Nairobi sheep disease(a)
Ndumu
Negishi
Oropouche (c)
Orungo
Peaton
Piry
Powassan
Puumala
Rift Valley fever (a,b,c,d)
Sagiyama
Sal Vieja
San Perlita
Semliki Forest
Seoul
Spondweni
St. Louis enc.
Thogoto
Tocio (c)
Turuna
Venezuelan equine(c,d) encephalitis
Vesicular Stomatitus (alagoas)
Wesselsbron (a,c)
West Nile
Yellow fever (c,d)
Zinga (b)
a.  The importation, possession, or use of this agent is restricted by USDA regulation or administrative policy.  See Appendix E.
b.  Zinga virus is now recognized as being identical to Rift Valley Fever virus.
c.  SALS recommends that work with this agent should be conducted only in Biosafety Level 3 facilities which provide for HEPA filtration of all exhaust air prior to discharge from the laboratory.
d.  A vaccine is available and is recommended for all persons working with this agent.
e.  This virus is presently being registered in the Catalogue of Arboviruses.96

Arboviruses, Arenaviruses, or Filoviruses Assigned to Biosafety Level 4

	SALS has recommended that work with the 15 arboviruses, arenaviruses, or filoviruses104 included in the alphabetical listing that follows should be conducted at the equivalent of Biosafety Level 4 practices, safety equipment, and facilities.  These recommendations are based on documented cases of severe and frequently fatal naturally occurring human infections and aerosoltransmitted laboratory infections.  SALS recommended that certain agents with a close antigenic relationship to the Biosafety Level 4 agents (e.g., Absettarov and Kumlinge viruses) also be handled at this level provisionally until sufficient laboratory experience was obtained to retain these agents at this level or to work with them at a lower level.  Laboratory or laboratory animal-associated infections have been reported with the following agents:65,86,90,109,151,178,194

Virus							Cases (SALS)

Junin							21 (1 death)
Marburg						25 (5 deaths)
Russian Spring-Summer encephalitis		8
Congo-Crimean hemorrhagic fever		8 (1 death
Omsk hemorrhagic fever				5
Lassa							2 (1 death)
Machupo						1 (1 death)
Ebola							1

	Rodents are natural reservoirs of Lassa fever virus (Mastomys natalensis), Junin and Machupo viruses (Calomys spp.) and perhaps other members of this group. Nonhuman primates were associated with the initial outbreaks of Kyasanur Forest disease (Presbytis spp.) and Marburg disease (Cercopithecus spp.); more recently, filoviruses related to Ebola were associated with Macaca spp.  Arthropods are the natural vectors of the tick-borne encephalitis complex agents.  Work with or exposure to rodents, nonhuman primates, or vectors naturally or experimentally infected with these agents represents a potential source of human infection.

	Laboratory Hazards: The infectious agents may be present in blood, urine, respiratory and throat secretions, semen and tissues from human or animal hosts, and in arthropods, rodents, and nonhuman primates.  Respiratory exposure to infectious aerosols, mucous membrane exposure to infectious droplets, and accidental parenteral inoculation are the primary hazards to laboratory or animal care personnel.109,194

	Recommended Precautions:  Biosafety Level 4 practices and facilities are recommended for all activities utilizing known or potentially infectious materials of human, animal, or arthropod origin.  A new, live attenuated investigational (IND) Junin virus vaccine (Candid #1) is available from the U.S. Army Medical Research Institute for Infectious Diseases (USAMRIID) and is recommended for all laboratory and animal care personnel working with the agent or infected animals and for all personnel entering laboratories or animal rooms when the agent is in use.  SALS has lowered the biohazard classification of Junin virus to BSL 3, provided all at risk personnel are immunized and the laboratory is equipped with HEPA filtered exhaust. Clinical specimens from persons suspected of being infected with one of the agents listed in this summary should be submitted to a laboratory with a Biosafety Level 4 maximum containment facility.23,141

Arboviruses, Arenaviruses and Filoviruses Assigned To Biosafety Level 4

Congo-Crimean hemorrhagic fever
Tick-borne encephalitis virus complex
(Absettarov, Hanzalova, Hypr,
Kumlinge, Kyasanur Forest disease,
Omsk hemorrhagic fever, and
Russian Spring-Summer
encephalitis)

Marburg
Ebola
Lassa
Junin
Machupo
Guanarito

.