August 24, 2026, 10:50 am | Read time: 3 minutes
Thailand is considered a paradise for foodies. On every street corner, food is fried, grilled, and seasoned, and many travelers try things they would never order at home. Those who delve deeply into the regional cuisine will sooner or later encounter specialties that are hardly known outside the country. One of these is Koi Pla. The traditional dish from northeastern Thailand is regarded as a delicacy among locals but has been a concern for medical professionals for years.
Koi Pla is particularly common in the Isan region of northeastern Thailand. For its preparation, small freshwater fish from rivers and lakes are finely chopped and then mixed with herbs, spices, and lime juice. The dish is considered affordable, quick to prepare, and is as much a part of daily life for many people as a sandwich or a bowl of soup is elsewhere.
The Invisible Danger in Raw Fish
This is what makes the situation so tricky. The danger does not lie in an exotic ingredient or a particularly daring preparation method. Rather, some of the fish used can be infested with tiny parasites that are not visible to the naked eye.
The greatest concern is the liver fluke, a parasitic flatworm found in the rivers of the Mekong region. If it enters the human body through raw fish, it can settle in the bile ducts. Often, those affected notice nothing for a long time, and only years or even decades later can the consequences become apparent—in the form of bile duct cancer, a rare but malignant tumor of the bile ducts.
Bile Duct Cancer as a Common Disease: Why Researchers Are Sounding the Alarm
The extent of the problem in parts of Thailand is shown by scientific studies from 2017. In the northeast of the country, around 22 million people live, millions of whom are considered at risk. In large-scale screening programs, researchers found unusually high infection rates with the parasite in some regions. In some areas, more than half of the people examined were affected, and in some communities, even significantly more. Various research institutes and health projects estimate that up to 20,000 people develop the disease annually, with many dying from its consequences.
To protect the population, doctors and researchers at the Cholangiocarcinoma Research Institute have been focusing on education and free examinations for years. The most important recommendation sounds simple: sufficiently heat freshwater fish before consumption. This kills the parasites. However, especially with traditional dishes like Koi Pla, many people find it difficult to give up a dietary habit that has been maintained for generations.