Ouch! Could you take that worm out of my bileduct, please?
There are three main species of oriental liver flukes infecting humans and their morphology and the way they affect us are quite similar.
All of them are hermaphrodites and betweeen 25 mm - 12 mm long and ca 1.5 mm - 5 mm wide, easily visible with the naked eye. Their geographic distribution is nevertheless different:
In non-endemic areas, like the U.S., the worm can be found in asian immigrants.
After the eggs have been excreted by their hosts into fresh water, their further development depends on the ingestion by a snail. There they mature until they are ready to face the water again, taken up by a fish, which, if eaten by human, will see the little buggers end up in the humans duodenum. Ignoring things like digestive enzymes and an utter acidic environment, the worms excyst their intermediate form and look for the ampulla vateri, just to climb up the common bileduct into the liver, to settle there in one of the smaller bile ducts. There they live quite undisturbed happily ever after, until the patient starts getting symptoms:
- some people complain about something moving around in their liver (how true!)
- abdominal pain
Untreated, these babies can cause liver cirrhosis and cholangiocarcinoma, both two rather deadly problems. Fortunately, praziquantel seems to get rid of them, but clever people shouldn't get them at all, making very sure that the raw fish they are eating didn't live in an endemic area, or
don't touch the stuff at all.
Dion R. Bell: "Tropical Medicine", 4th edition, Blackwell Sciences, 2000