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03/20/10(Sat)09:05 No. 4680267 File1269090352.jpg -(34
KB, 455x320, cysticerci brain.jpg ) >>4680261 Oh
dear, after a dozen "field too long" errors I forgot to sage. I'm
sorry. The fecundity of tapeworms, as expected from parasites,
is astounding - fish tapeworm releases up to 1,000,000 eggs per day and
can live for 20 years, dwarf tapeworm Hymenolepis nana, merely a few
centimeters long, can release about 2500 proglottids each carrying 200
eggs in just 20 days. Speaking of H. nana, it is unique amongst
tapeworms as it has eliminated the need for intermediate hosts - the
eggs can just hatch in the same host after being released, meaning one
dwarf tapeworm will soon make a lot of dwarf tapeworms. As long
as humans are definitive hosts, tapeworms are mere annoyances, except in
children where they may be fatal (though not in any developed country. )
However, poor tapeworms don't know nothing really eats humans in this
day and age, and may end up infecting them as intermediate hosts, which
involves forming cysts as mentioned. As the eggs travel via bloodstream,
they can lodge themselves into practically everywhere - lungs, eyes,
tongue or even the brain is within their reach. There the tapeworms wait
(for up to perhaps ten years, usually unnoticed except for say,
Echinococcus, which I'll mention below) for their human host to be
eaten, which, unfortunately for them and unfortunately for the human,
seldom happens; so the worms end up dying. While alive, they can bypass
the immune defenses of the host, else an egg would be ripped to shreds
by lymphocytes (or glia in the brain. ) But once they're dead, your body
suddenly notices there's a big lump of dead tapeworm inside you. Cue
massive immune response for larger cysts (or those in the brain), which
may lead to death in most extreme of cases.