One of the most popular spicy food dishes of Isaan, north eastern Thailand, is made using small fish caught from rivers and lakes and is called koi plaa. The fish are finely chopped and mixed by hand with herbs, lime juice and live red ants. The dish is traditionally served raw and is rather pungent.
For many decades there have been abnormally high occurrences of liver cancer in specific areas of Issan. In men liver cancer accounts for more than half of all cancer cases, compared to an average of less than 10% worldwide. These high levels of liver cancer in Thailand have been linked to infection by liver flukes, which is a parasite, found in raw fish.
Is it safe to eat koi plaa?
Yes, if the dish is cooked thoroughly before eating. Cooking the fish kills the flukes.
How do the flukes cause cancer?
Studies at Tropical Disease Research Laboratory in Khon Kaen University revealed that the flukes trigger a chemical stimulus within an infected liver which causes an immune response and inflammation. After many years the inflammation becomes chronic and can then become cancerous.
Dr. Banchob Sripa and his team at the University have been studying the effects of fluke infestation of the liver for over 30 years. They discovered that in hotspot areas, where uncooked koi plaa is very popular, up to 80% of people were infected by the fluke. Even children as young as 4 years old were found to be infected. The liver cancer doesn’t normally develop before people reach 50. Once the cancer develops, there is often very little the doctors can do to save the patient. Around 10% of those diagnosed with the disease, cholangiocarcinoma can be treated. The University hospital deals with around 2,000 cases a year.
With such a high mortality rate, the only real cure is prevention. Dr. Banchob and his team have made it their mission to educate people and are running a community based health programme in the villages along Lawa Lake, which is south of Khon Kaen. This is where liver fluke infections are greatest in number.
One method that is proving a success is educating the people through music and humour. The team have composed several songs that explain the life cycle of the fluke. It’s actually quite horrible! The larvae, embedded in the fish’s flesh, when eaten grow into adult flukes inside the liver. The fluke eggs are then excreted by the infected individual, which then pass back into the water system where they are eaten by snails, before the larvae infect another fish! Yuk!
The attitude of the youngsters in the villages has been encouraging, but older people find change difficult so part of the education campaign is to help prevent reintroducing new eggs into the water system. People are being encouraged to use proper toilets and discouraged from defecating in the lake.
As a foreigner, you are unlikely to eat koi plaa because of its pungent smell and super spicy taste, however if you are ever offered the dish and wish to try, make sure it’s been cooked first.