Doctors are warning the 1 million Americans who visit Thailand annually to avoid a local dish that has been called “the world’s deadliest meal.”
Koi pla is made from raw fish grounds with herbs and lime and ‘just one bite’ is enough to cause cancer.
The freshwater fish from which it is made are at high risk of becoming infected with parasitic worms known as liver fluke.
Once in the body, these microscopic parasites cause inflammation that damages cells and leads to cholangiocarcinoma (CCA) bile duct cancer.
Boston-based food policy expert and professor at Northeastern University, Dr. Darin Detwiler, told DailyMail.com: ‘If the fish harbors the parasite, any consumption of raw meat can introduce the parasite into the body, which can lead to infection.
“It only takes one bite.”
Koi pla, made from raw fishing grounds with herbs and lime, is a favorite feast for parasites responsible for deadly liver cancer, doctors warn
Over the past few decades, extensive efforts have been made to raise awareness of the raw fish link in an effort to curb rates.
Other meals made from raw fish, such as pla som, pla jom and pla ra, can also cause cancer because they contain the same type of fish as koi pla.
But despite warnings, a 2023 study found that these dishes are still popular in northeastern Thailand, which is thankfully less touristy than the south.
The research, led by Yi-Chen Wang of the National University of Singapore, involved surveys in three sub-districts – Ban Kaengt, Na Tan and Non Phayom – in three provinces in the area.
A total of 820 questionnaires were collected, with 66 percent of respondents confirming that they eat raw fish despite being aware of the risks.
Nearly 70 percent of participants correctly understood that eating raw fish could lead to parasitic infections.
More than a quarter of participants (28.3 percent) incorrectly believed that other raw foods, such as raw shrimp, raw beef, vegetables and fruit, were also the source of liver fluke infections.
One of the leading causes of bile duct cancer, which kills 20,000 Thais every year, is a parasitic flatworm native to the Mekong region and found in freshwater fish.
When asked about the best methods to kill the parasite, 10 percent of respondents wrongly believed it could be killed by adding other ingredients such as vinegar, lime juice, alcohol or red ants.
The best way to kill liver fluke is to cook the fish thoroughly before consuming it.
Fish liver flukes are killed at an internal temperature of at least 145°F, or you can freeze fish at -4°F for at least seven days.
For consumers in regions outside Thailand, where raw freshwater fish is less common, the risk is much lower, but Dr. Detwiler told DailyMail.com that the risk still exists from improper food handling.
He said: ‘This particular parasite (opisthorchis viverrini) is not common in the US.
‘However, foodborne parasites from raw or undercooked fish still pose a risk, including tapeworms and other flukes.
‘The parasite that leads to liver cancer in Thailand is mainly found in Southeast Asia, especially in regions where raw freshwater fish dishes are popular.
The best way to kill liver fluke (photo) is to cook the fish thoroughly before consuming it, or by freezing it
‘Cases of infection with Opisthorchis viverrini have been reported in the US, but these are rare.
‘Infections in the US are typically ‘imported cases,’ meaning the individuals acquired the infection abroad and later developed symptoms.
‘Cases are generally linked to individuals who have emigrated from or traveled to regions where the parasite is endemic, such as Southeast Asia.
‘Specifically, the majority of these cases have been observed among refugees from Vietnam, Laos, Cambodia and Thailand, especially in communities where the consumption of raw or undercooked freshwater fish is common.’
Outside Thailand, koi pla is not a popular dish and is very rarely found on restaurant menus.
The recent study calls for more education about liver fluke and its prevalence in raw fish.
It also highlights the need for effective disease control programs, and the researchers found that a resurgence of infections often occurred once a program was stopped.
They add: ‘The success of a national health care program (in Thailand) depends largely on community support to implement educational campaigns, promote public awareness and facilitate individual behavior change.’