Doctors are warning the million Americans who visit Thailand each year to avoid a local dish dubbed “the world’s deadliest food.”
Koi pla is made from raw fish ground with spices and lime and “just one bite” is enough to cause cancer.
The freshwater fish from which it is made has a high risk of being contaminated with parasitic worms known as liver fluke.
Once in the body, these microscopic parasites cause inflammation that damages cells and leads to bile duct cancer cholangiocarcinoma (CCA).
Dr Darin Detwiler, a Boston-based food policy expert and professor at Northeastern University, told DailyMail.com: ‘If fish harbors the parasite, any consumption of raw meat can introduce the parasite into the body and cause a infection.
“It only takes one bite.”
Koi pla, made from raw fish ground with spices and lime, is a favorite feast of the parasites responsible for deadly liver cancer, doctors warn.
In recent decades, great efforts have been made to raise awareness of the link to raw fish in a bid to curb tariffs.
Other foods made with raw fish, such as pla som, pla jom, and pla ra, can also cause cancer since they contain the same species of fish as koi pla.
But despite the warnings, a 2023 study found that these dishes remain popular in the northeastern part of Thailand, which is thankfully less touristy than the south.
The research, led by Yi-Chen Wang of the National University of Singapore, conducted surveys in three sub-districts (Ban Kaengt, Na Tan and Non Phayom) in three provinces in the area.
A total of 820 questionnaires were obtained and 66 percent of respondents confirmed that they eat raw fish despite knowing the risks.
About 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 meat, vegetables and fruits, were also sources of liver fluke infection.
One of the main causes of bile duct cancer, which kills 20,000 Thais each 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 incorrectly believed it could be killed by adding other ingredients, such as vinegar, lime juice, alcohol or fire ants.
The best way to kill liver fluke is to cook fish thoroughly before eating.
Fish liver flukes die at an internal temperature of at least 145°F or you can freeze the fish at -4°F below 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 it still exists if food is handled improperly.
He said: ‘This specific parasite (opisthorchis viverrini) is not common in the United States.
‘However, foodborne parasites from raw or undercooked fish remain a risk, including tapeworms and other flukes.
‘The parasite that causes liver cancer in Thailand is predominantly found in Southeast Asia, particularly in regions where raw freshwater fish dishes are popular.
The best way to kill liver fluke (pictured) is to cook the fish thoroughly before eating or freezing it.
‘Cases of Opisthorchis viverrini infection have been reported in the US, but are rare.
‘Infections in the United States are often “imported cases,” meaning people acquired the infection abroad and then developed symptoms.
«Cases are generally related to people who have immigrated 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, particularly in communities where the consumption of raw or undercooked freshwater fish is common.”
Outside of Thailand, koi pla is not a popular dish and is 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 researchers noted that a resurgence of infection was common once the program ceased.
They add: “The success of a national health monitoring program (in Thailand) largely depends on community support to implement educational campaigns, promote public awareness and facilitate individual behavior change.”
