Koi pla, a cheap raw fish ground with spices and lime, is a popular raw fish dish usually eaten by Thais and Thai food lovers. It is also believed to kill up to 20,000 Thais per year.
The dish, which is usually eaten in the country's rural north-east, is believed to contain parasites that cause a form of cholaniocarcinoma, or bile duct cancer. The aggressive cancer is caused by the liver fluke, a parasitic flatworm native to fresh water fish in the Mekong region.
Without surgery, the disease has one of the lowest survival rates of all cancers.
A team of doctors spent 4 years conducting health screenings in Isaan testing villagers for the parasite. Up to 80% of the inhabitants in that region were found to have ingested the parsite. A third of these villagers showed abnormal liver symptoms and 4 were suspected to have cancer.
Despite government efforts to discourage the consumption of the raw fish dish, old traditions are hard to kill. The dish continues to be consumed raw by unsuspecting tourists and villagers alike.