Stupid People Tricks: The raw crawfish conundrum

This is a cautionary tale.

On Memorial Day weekend, 2006, a man ate a live crawfish. Two, to be precise. Why did he eat two live crawfish? He was on a float trip on the Current River, and he was drunk. It's possible his friends were egging him on. People do this. They videotape themselves, and then they post it on YouTube.

The videos have a distressing sameness to them. A young man — it's always a young man — holds the crawfish up to the camera and tries to make it wiggle to prove that it's still alive. If he's the prudent type, he twists the claws off first. If he's more foolhardy, he just bites the head off. Then he chews. He chews for a long time, through layers of shell and tissue. The expression on his face turns doubtful. Does he really want to go through with this? His friends cheer, tell him not to be a pussy. After what seems like forever but is probably more like a minute in real time, he swallows. He opens his mouth and sticks out his tongue. The camera zooms in. In the background, someone comments on the crawfish guts sticking to his lower lip.

Our protagonist did not star in any of these videos, but he did, as you'll recall, eat two of the suckers. And a couple of months after his float trip, sometime in July 2006, he started to feel sick. He had a fever and a persistent cough. A doctor at his local emergency room decided he had a tick-related infection and prescribed a weeklong round of antibiotics. But this didn't make him feel any better. In fact, he started to feel worse: headaches, night sweats, chills, shortness of breath and a dramatic weight loss.

Eventually, the patient ended up at Barnes-Jewish Hospital, the course of last resort for many patients in Missouri, in the department of infectious diseases, in the care of Dr. Thomas Bailey. Further examination showed that the patient had a buildup of fluid around his lungs and an elevated white cell count, a possible indication of infection.

During the course of the medical-history interview, the patient's wife casually mentioned the two crawfish. ("Once you see [elevated white blood cells], it's a clue, and you start asking about strange things," says Dr. Michael Lane, a colleague of Bailey's.)

Bailey did what anyone in his situation would do: He ran a Google search to look for any connection between an elevated white blood cell count, a buildup of lung fluid and crawfish. He came up with something called paragonimiasis, an infection caused by a parasite that lives in the hearts of crawfish. It's fairly common in China, where it's carried in crabs and spread via a local delicacy called drunken crab in which the raw crustacean is marinated in alcohol. In the United States, however, where people tend to cook their shellfish, there had been a grand total of seven cases reported in humans since 1967.

Bailey consulted a colleague in the infectious-diseases department, Dr. Gary Weil, who specializes in parasites. Almost immediately, they started referring to the crawfish as Ozark sushi, but Weil thought the paragonimiasis diagnosis was far-fetched. For one thing, there weren't any signs of the parasite, such as eggs, in the patient's phlegm. For another, a paragonimiasis test developed by the Centers for Disease Control and Prevention in Atlanta came out negative.

"It could have been pneumonia or an allergy or breathing in a housefly," Weil recalls. "But Bailey seemed pretty convinced."

Bailey was even more convinced after all the patient's symptoms disappeared after two days of treatment with praziquantel, a drug used to kill parasitic worms. A lung biopsy later revealed DNA traces of the parasite, formally known as Paragonimus kellicotti. As it turned out, the reason the CDC test found nothing was because it was checking not for Paragonimus kellicotti but for Paragonimus westermani, its Asian cousin.

The following summer, two more cases of paragonimiasis turned up at Barnes, both in patients who had eaten raw crawfish in the past year. By 2010, Bailey, Weil and Lane had treated five cases in total, and Dr. Scott Folk, a doctor in St. Joseph, had found three more. It was probably less a full-fledged epidemic than a case of the doctors knowing what to look for — "If you've seen it once," says Lane, "it sticks with you" — but it was definitely cause for concern.

Strangely, although the physicians made inquiries in other states, particularly Arkansas and Louisiana, where people eat a lot of crawfish, all the cases were in Missouri. That wasn't the only thing patients had in common.

"You'll notice," Bailey points out, "that all but one of the reported cases so far has been a guy." All but one of the cases involved drinking; the lone exception was a ten-year-old who wanted to prove to his cousins that he could survive in the wild. And, in most of these cases, it wasn't country folk who were dumb enough to chomp down on these crawfish; it was city slickers who find that nothing enhances a weekend float trip like vast quantities of alcohol.

For Weil, an infectious-disease specialist who spends a lot of his time flying to far-flung places like Indonesia to study tropical diseases like elephantiasis, a bacterial infection that causes gross swelling of the legs and genitals, it's a refreshing change to be able to look at something closer to home.

"It's like Alien," he says excitedly. "The astronaut's exploring a new planet, and he sees this egg thing. He touches it, and it explodes all over him. They take him to the clinic, and he seems fine, but this thing has gotten into him, and it starts to grow. And then the mature alien bursts out of his chest! That's science fiction, but this is real."

It's also considerably less dramatic. Like the titular alien, Paragonimus kellicotti begins as an egg. Unlike the alien egg, however, it's a tiny, translucent yellow blob that's been expelled from its animal host via phlegm (which the doctors, with medical delicacy, call "sputum") or shit ("stool"). The egg lands in the water supply where it's ingested by an unsuspecting snail. There it hatches and waits for the snail to become food for the next intermediate host, the crawfish. Once it reaches the crawfish, the parasite makes a little home for itself in the heart where it grows into a very tiny worm called a fluke. It'll reach maturity in its final host, an unsuspecting dog or cat or possum...or a drunken human.

If a Paragonimus kellicotti hits the right combination of snail and crawfish and if that crawfish manages to get ingested by a human or another mammal without getting cooked first, which would kill both the crawfish and any other living creatures it harbors, it has won the parasitic lottery. Paragonimus kellicotti like the inside of warm-blooded creatures. Particularly their lungs.

As soon as the crawfish hits the first stretch of the small intestine, an onslaught of digestive enzymes warns the parasite that it's time to move. It burrows through the intestinal wall and the diaphragm, the muscle that separates the digestive system from the heart and lungs. Since the fluke is now approximately a centimeter long, some human hosts can feel the burrowing. Some get diarrhea. In at least one patient, doctors mistook the pain for a gall-bladder attack. Once the gall bladder was removed, it turned out to be perfectly normal.

In the lungs, the fluke settles in for the long haul and goes about the business of living and reproducing. (They're hermaphrodites, but they're more successful if they travel in pairs.) Its life expectancy is between five and ten years. "We don't know a lot about the biology," Lane admits.

What the doctors do know is that the parasite causes the lungs to fill up with fluid, similar to the effects of pneumonia. If it goes untreated, the fluid can spread throughout the chest cavity and surround the heart and, eventually, the pressure will stop it from beating. Lane hasn't seen this happen in any of his patients, though one did die when the fluid became infected. "It was a bad set of circumstances," he says, "two bad things coming together."

Sometimes the flukes go astray. Lane and Weil have seen them as far afield as the hand and, in one case, the face, where the lost fluke formed a small but visible — and moving — nodule under the skin. In two cases, flukes wandered into the brain, specifically the part that affects vision. One patient suffered from partial blindness. Another had bad headaches and saw "floaters," blind spots in his vision.

Because paragonimiasis looks a lot like several other, more common, medical problems, a lot of money has been spent on unnecessary treatments: rounds of steroids, repeated draining of the lungs, the aforementioned gall-bladder removal. One patient had been misdiagnosed with lymphoma and was about to start chemotherapy.

Weil's lab is working on developing a test for paragonimiasis similar to the CDC version, except that it will detect antibodies or DNA from Paragonimus kellicotti instead of westermani. But the doctors think it would be preferable to keep people from getting infected in the first place, or at the very least let their colleagues around the state know what to look for.

"We don't want to have patients having unnecessary surgery," says Lane. "It's expensive, and they don't do well. It's not the best medicine."

To that end, last summer the Missouri Department of Health and Senior Services issued a physicians' advisory and started hanging posters in stores that sell equipment for float trips that read "Do NOT eat raw crayfish." (In the .gif version saved on Weil's office computer, he's added the phrase "you idiot.")

Lane and Weil haven't seen any cases this year (though they did hear of one at the St. Louis VA Medical Center in the spring), but it's still early. "In prior years," Weil says, "people who were infected over Memorial Day or the Fourth of July start showing symptoms in August or September."

The whole phenomenon still puzzles him. "You've got to be nuts to eat a raw crawfish." He walks over to the fish tank in his lab that holds a single live specimen. "Look! They've got pinchers!" He shakes his head. "If you want to eat something, eat a tadpole. It's soft, and it's not infectious."