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Don't eat raw crawfish or a worm might invade your insides

For those who need another reason, beyond the ick factor, to not eat raw crawfish, here’s a frightening fact: many of these crunchy crustaceans carry the infinitely more icky lungworms – which can burrow from your digestive tract into your lungs, cheeks, or even your brain.

A new government report describes the cases of nine Missouri folks whose bodies were invaded by the parasitic little flat worms, officially known as paragonimus kellicotti, after gobbling down raw crawfish on a drunken dare.

All nine got infected with paragoniumus between 2009 and 2010. Before that, there had been just seven cases reported between 1968 and 2008, according to the new report published this week in Emerging Infectious Diseases, a Centers for Disease Control and Prevention journal. Why the upsurge? Turns out that people in the country’s interior like to cool off by rafting down rivers -- which are populated by crawfish. And someone, somewhere, got the brilliant idea to dare a friend to gobble down a live one.

“What we’ve seen is that out on rivers people like to drink and do some things we might not normally do,” says study co-author Michael A. Lane, an assistant professor of medicine in the division of infectious diseases at the Washington University School of Medicine. “We’ve seen a decent – though still relatively small – number of people eating raw crawfish on a dare after drinking beer.”

If you’re having trouble imagining someone consuming a live crawfish, just type the words “eating raw crawfish” into the search bar on YouTube and you’ll see plenty of people crunching away. Best to do this on an empty stomach. 

Scientists have discovered that many of the crawfish in Missouri’s rivers are infected with lungworms. “In some rivers as few as 40 percent of the crawfish had the parasite,” Lane says. “But in others it was as high as 70 percent. So, if you pull a crawfish out of the water, you’ve got a high likelihood of getting one with the parasite.”

The parasites are about the size of a grain of rice when they’re in a crawfish, Lane says. But they can grow as big as a half an inch once they’re inside the human body.

“After you eat the crawfish, the parasite comes out and migrates across the diaphragm,” Lane explains. “They burrow through the walls of the intestine, hoping to make it to the lungs where they can complete their life cycle and mature. Once in the lungs they form nodules that mature and grow. But sometimes they get lost on the way to the lungs and they can end up in other places. One of our patients had one that had gone to the brain. Another had one that had worked its way to the cheek.”

Lane’s study only looked at people who had been seen at his medical center, but Missouri isn’t the only place with hot weather, rivers and crawfish.

“All the pieces of the parasite’s life cycle are found throughout the country,” Lane points out. “There have been animal studies that have found them in Ohio, Colorado, and other places.”

Because of that, Lane suspects there may be even more cases of people out there with paragonimus symptoms – coughing, fever, shortness of breath, high white blood cell count, fluid in and around the lungs - who are being misdiagnosed with anything from tuberculosis to pneumonia to cancer.

And the misdiagnoses may cause more damage than the worm itself. One of Lane’s patients was on the verge of getting treated for cancer because doctors assumed that had to be the problem.

“He’d had multiple procedures for draining the fluid from his lungs – which eventually caused one of his lungs to collapse,” Lane says.

Another patient had a healthy gallbladder removed when doctors couldn’t find any other explanation for his chest pain.

The good news is that there is a very effective therapy. When patients take the medication praziquantel for three days, there is a 100 percent cure rate, Lane says.

The tricky thing is for doctors to first figure out whether a patient has the parasite since there is no good blood test.

“Probably the best diagnostic test we have is to ask the patient if they ate any raw crawfish,” Lane says. 

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