Wednesday, November 23, 2005

Echinococcus (Hydatid Disease)

So what brings this topic up? I was watching 'House' last night. I really like the main character because he is a curmudgeon but really smart. In any case, a couple of people ended up diagnosed with Echinococcus infection, one of my favorite cestode helminths. House COMPLETELY mispronounced the name of the parasite which of course made me laugh. I'm pretty sure the medical advisor to that show probably didn't know how to pronounce it either (E KINE OH COCK US) not (ECHO NO COCK US) or something like that.

There are two major species of Echinococcus that infect man. The two individuals last night were infected with Echinococcus granulosus, which can at least be treated surgically by removing the cysts. But I'm really not sure that E. granulosis is commonly found in the USA, even in the Northwest sheep raising country. However, E. multilocularis has been reported in Canada and Alaska I believe. In any case, if these cestode infections are found in the USA, it is more likely in a feral rather than domestic cycle. So hunters beware. There is no treatment for E. multilocularis as far as I'm aware. You just die.

Why is that?


Hydatid cysts cause by infection with E. granulosus look like those above. They are individual cysts and the brood capsules grow off an INTERNAL germinal layer. One problem with these cysts is that they are filled with fluid that causes severe anaphylactic shock if they are broken open. This happened to the guy last night after House hit him with his cane. Luckly it happened in the hospital. By the way, the guy (father) had been diagnosed with cirrhosis of the liver and the son with a tumor of the heart and lungs. Hydatid disease often presents with signs resembling cancer.


Infection with E. multilocularis is very different and very scary. In this infection the germinal tissue of the cyst is located on the OUTSIDE resulting in malignant spread of the cyst. The cyst is not defined or contained as with infection with E. granulosis and thus cannot be easily removed.

So how do you prevent yourself from being infected with these dreaded cestodes? Very simple. Don't eat infected dog, fox, wolf, dingo or coyote shit.

Sometime when you are bored, ask me about infection with the dreaded Baylisascaris worm (brain worm).

1 comment:

B-Wizz said...

I watched too - I'm sure that Cindy will be pleased to see that someone in the know has commented about something from one of her favorite shows. They did say that they had contracted it from trapping foxes in MT, not from domestic animals.

I'm surprised at the mispronunciation (not that I caught it while I was wathing). Anyone one who's ahd any basic level bio course (most high school courses, I'm sure) picks up some latin pronunciation. Echinoderms, hello?