ST. LOUIS — When Adam Brewer tagged along with a friend's family for a float trip down the Jack's Fork River in southern Missouri last June, he also decided to join in one of their family traditions — eating raw crawfish.
"Uncles and older cousins on the float trip had been doing it for years, to make the little kids laugh," said Brewer, a 19-year-old college student from Florissant. "So I just kind of joined in."
It wasn't until September that Brewer got sick. First he thought he had the flu. Then his lungs filled with fluid. Over the next several months, doctors checked him for pneumonia, blood diseases and cancer.
Finally, in March, physicians from Washington University came up with the diagnosis: A rare but severe parasitic infection caused by the raw crawfish Brewer had eaten nine months earlier.
Crawfish — also known as crayfish or crawdads — are common in Missouri and many other states. They look like small crabs and live under rocks in rivers, streams, creeks and ponds. They're fine to eat, as long as they're cooked.
Raw crawfish are no delicacy — Brewer can attest to the fact they don't taste good — so eating them fresh from the river may seem like an odd choice.
Still, the practice is common enough that last year, the Missouri Department of Health and Senior Services put out a warning urging people not to do it. Posters have been placed at some state parks.
"They're mostly intoxicated when they do it," said Dr. Gary Weil, professor of medicine and molecular microbiology at Washington University. "Sometimes they're just showing off, but it is a nutty thing to do. And they pinch."
Washington University physicians have treated six people with illnesses caused by eating raw crawfish in the past three years — all from rivers and streams in Missouri. Three of the cases, including Brewer's, have occurred since September. Before the six Missouri cases, only seven other cases of the infection, paragonimiasis, had been reported in North America.
Another Washington University physician, Michael Lane, said there are probably many other cases that have not been diagnosed.
"I think we're potentially seeing the tip of the iceberg from people going out on the river, having a good time, having too much to drink and enjoying some 'Missouri sushi,'" Lane said.
The parasitic worm that causes the infection is the size of the tip of a pen when ingested but can grow to the size of a grape once inside the human lung, Weil said. They usually travel from the intestine to the lungs and sometimes to the brain, where they can cause severe headaches and vision problems. Washington University physicians treated one man who went partially blind from the parasites. He recovered his eyesight after treatment.
Symptoms include fever, difficult or labored breathing, chronic cough, coughing up blood and chest and abdominal pain.
The illness is curable but rare enough that physicians often overlook it. Symptoms, if left untreated, can persist for years, even decades.
The infection is treated with an oral drug, praziquantel. Within a week to 10 days, experts say, symptoms are generally gone.
After months of illness and undergoing agonizing tests over and over again, Brewer said he recovered almost immediately once his ailment was diagnosed. He said he learned a lesson the hard way.
"Don't eat anything raw out of the river," Brewer said. "I'd never do it again."