Doesn’t this happen in higher mammals too? Don’t tapeworms come clamoring out of your anus after you die, searching for a compatible new host? Or is that just the product of preadolescent campfire story mythology? Wiki is uncomfortably silent on the subject, but does mention that the little buggers have been observed to grow up to lengths of 59 feet.
No, tapeworms have essentially no musculature and can’t crawl anywhere. They are basically just a head and a bunch of reproductive segments. They infect new hosts by means of eggs that the hosts ingest.
The life cycle is a bit more complex. Adult tapeworms shed segments which DO come out of the anus of the (still living) host. They are about the size and color of a grain of rice…and they do wiggle a bit while fresh. (and it is damned creepy to see, let me tell ya!) These are consumed by rodents, and then produce blood-born eggs. If/when the rodent is consumed by a carnivore the eggs hatch and the carnivore becomes infected by the adult tapeworm.
The cure for tapeworms is interesting. Since they live in the host’s small intestine, they have a coating that keeps the from being absorbed as food. The cure bypasses this coating, and the worm is then digested…one dose and the parasite is history.
[pant] [pant] I think the most horrible thing about that whole description is that it actually got me feeling sorry for cockroaches. Poor old roach-zombies.
Depends on the species of tapeworm. Humans don’t normally become infected by eating rodents, or carnivores that eat rodents. The most common intermediate hosts for human tapeworms are cattle, for the beef tapeworm, and pigs, for the pork tapeworm. These become infected by ingesting eggs in food contaminated by human feces. Humans acquire the parasites by eating infected meat. In the case of the pork tapeworm can also become infected directly by ingesting eggs.
In any case, while proglottid segments can squirm around a bit, the whole worm doesn’t come squirming out of the anus in search of a new host, as Washoe’s post suggested.
My favorite tapeworm joke, which was originally told to me by my mother, a registered nurse:
Yes but still good info. I’ve taken both pathopsysiology & parasitology courses and didn’t know this (or didn’t remember). The courses usually just stuck to the relationship of the organism and humans.
That reminds me—what was the deal with those people who had the bizarre threads or strings sticking out of their skin? I think I remember hearing on TV that they had solved it, but I can’t remember what the upshot was. There was a thread about it here, but I can’t remember the name of the disease.
