RESUMEN
A cross sectional survey on opisthorchiasis was conducted from August to September 1933 in Tambon Nai Muang, Sawankhalok district, Sukhothai Province. The 1,964 villagers were stool examined and it was found that 384 of them had liver fluke infection. Of these 1,608, who were older than 12 years, were interviewed in order to detect potential risk factors of liver fluke infection. The study found that the population at risk were those older than 24 years of age (p < 0.05) and the possible risk factor was eating incomplete cooked fresh water fish (p < 0.05). The food prepared from incomplete cooked fish which was harmful to the villagers were pickle fish so called pla ra (p < 0.05) and papaya salad with pickle fish so called som tam pla ra (p < 0.05).