The villagers in this poverty-stricken farming community are passionate about their food, especially the traditional varieties of fermented fish that one fan describes as tasting like heaven but smelling like hell.

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LAWA, Thailand — The villagers in this poverty-stricken farming community are passionate about their food, especially the traditional varieties of fermented fish that one fan describes as tasting like heaven but smelling like hell.

It can be a fatal attraction, medical researchers say. The raw fish that is so avidly consumed in the stilt houses here that sit among the rice paddies and wetlands of the country’s northern provinces contain parasites that can accumulate in the liver and lead to a deadly cancer, according to the researchers.

Known as bile-duct cancer, it is relatively uncommon in most parts of the world but represents the majority of the 70 liver-cancer deaths a day in Thailand, according to Dr. Banchob Sripa, the head of the tropical-disease research laboratory at nearby Khon Kaen University.

“It’s the most deadly and persistent cancer in the region,” Banchob said.

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For the last three decades, he has led a campaign against the parasite, known as a liver fluke, which is also endemic in Cambodia, Laos, Vietnam, parts of China, the Korean peninsula and Siberia.

Dr. Peter Hotez, the president of the Sabin Vaccine Institute, a nonprofit organization in the United States that researches neglected tropical diseases, described liver flukes as one of “the most important infectious causes of cancer that no one has ever heard of.”

Cooking the fish would eliminate the risk of infection. But the battle against liver flukes is being undermined by a deeply ingrained love of the sour and smoky-tasting fermented dishes that generations of villagers have relished.

Some villagers just cannot break the habit, said Nutcharin Yanarangsri, a volunteer at a government health clinic here in the village who spends her days walking from house to house with a singular message: “Say no to raw fish!”

“We tell them, ‘If you really want to eat it, you’d better boil it or cook it,’ ” Nutcharin said during one of her rounds through the village. “But they tell me: ‘Eating it raw is so delicious. I can’t stop. I love it!’ “

It is hard to overstate the love of food in Thailand. Be it a green papaya salad with just the right mix of sweet and sour, or a duck curry swimming in spices, the country’s 65 million people seem to spend their waking hours either talking about food or eating it.

But the obsession also has a masochistic side. It is not uncommon for office workers to dine on five-alarm chili-laced dishes for lunch, only to rush to the bathroom a few hours later with a bad case of Bangkok belly.

The love of fermented foods, especially in northeast Thailand, also largely overpowers any consideration of the consequences.

One popular dish in northeast Thailand is called pla som, or sour fish, which is made by mixing raw fish, garlic, salt, steamed rice and a pinch of seasoning powder. The mixture is shaped into egg-size portions, put into plastic bags and left to sit in the tropical heat for three days. That is not nearly long enough to kill the parasites, which die only after at least six months of fermentation.

Liver flukes are present only in fresh water and are very localized. In Bangkok, a five-hour drive away, there is almost no infection from them.

Transmitted through feces, the parasites thrive in rural areas without proper sanitation, and their life cycles involve using snails, fish, cats and humans as hosts.

Yet villagers do not see fermented fish as a dangerous thrill.

It is not comparable to the tradition in Japan of eating fugu, the puffer fish that is potentially toxic when prepared the wrong way.

The deadly effects of eating parasite-infected raw fish accumulate over decades, similar to drinking large amounts of alcohol over a lifetime and ruining one’s liver. (Heavy drinking increases the chance of bile-duct cancer for those infected with the parasite, according to Banchob.)

Anywhere from 1 to 5 percent of people infected with the parasites contract liver cancer, researchers say.

Laos, Vietnam and Cambodia also have high rates of liver cancer, according to U.N. statistics. Banchob estimated that about 10 percent of the population in Laos was infected with liver flukes.

Hotez, of the Sabin Institute, groups the parasite with a number of other worms and ailments that rarely afflict wealthy urban populations and thus attract relatively little attention.

“Even though Thailand is a middle-class country, there are still pockets of intense poverty — and with that poverty come high rates of neglected tropical diseases,” Hotez said. “We’ve got the technology to make vaccines. But we don’t have the funding.”

Dr. Cherdchai Tontisirin, a surgeon in Khon Kaen who has operated on liver-cancer patients, blamed the Thai government for the persistence of the disease. More could be done to make sure villagers stop eating raw fish, he said.

“The government has never taken this seriously,” Cherdchai said. “This is a disease that affects only the north and the northeast, and these are regions that have been forgotten for a long time.”

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