River trip + raw crayfish = possible nasty parasite

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Heading to any freshwater streams or rivers this summer where the crayfish run? Take it from us: Don’t eat the crayfish raw. Seriously. It might not end well.

You could pick up a terrible parasite. Before we tell you more, if you’re at all squeamish, stop reading. Don’t say we didn’t warn you.

A review article in the journal Clinical Infectious Diseases outlines three case studies of patients who sought treatment for symptoms such as fever, cough, shortness of breath, severe fatigue and chest pain. Some patients had been treated for months before being diagnosed with paragonimiasis, a rare, non-fatal parasitic infection caused by Paragonimus kellicotti, commonly found in raw crayfish.

The parasites are nasty little critters, oval-shaped and about half an inch long. Once eaten, they can work their way from the intestines to the lungs. But they can also take a little longer trip and go to the brain, causing bad headaches and vision problems. These worms can also be seen under the skin, as a news release says, ‘appearing as small, moving nodules.’ Wrap your head around that for a minute.

The three documented cases were only half of all patients with paragonimiasis seen at Washington University School of Medicine in St. Louis in the last three years, the last three cases diagnosed since last September (the most recent one was in April). The three were all previously healthy people age 26 to 32 who came in with some similar symptoms, including fever, cough and malaise. One had severe headaches and blurred vision. After the patients were treated for what doctors thought they had (such as pneumonia), their symptoms would sometimes abate, only to reappear. When the patients ultimately told about a recent trip to a freshwater river or stream, health professionals started to put the pieces together. Especially when each patient admitted to eating raw crayfish. What might compel people to do that? This might give you a clue: They were all intoxicated at the time.

The patients were then given anti-parasite medication that eradicated the creatures. All of the patients fully recovered.

Even though paragonimiasis is a rare infection, the study authors worry that there may be more people who have ingested the parasite but haven’t been diagnosed. So don’t eat raw crayfish on a dare, don’t drink while paddling down the river, and be sure to cook your crayfish.

-- Jeannine Stein