ABSTRACT
The prevalence and intensity of Opisthorchis viverrini in fourteen villages in Nakhon-Phanom province, Northeast, Thailand have been investigated. Overall prevalence of O. viverrini infection was 66.4 per cent in a total population of 2,412 individuals. The prevalence was 18.5 per cent in children under 5 years, 38.9 per cent in those aged 5-9 years, and ranged from 64.9 per cent to 82.2 per cent in the age group above 10 years. The intensity of O. viverrini infection increased with age. The mean faecal egg output was highest in the 30-34 year age group and remained relatively constant through older ages. In all age groups the prevalence and intensity of infection in both men and women were similar. The population was divided according to the presence and intensity of infection as follow, 33 per cent were uninfected, 59 per cent had light infections (less than 1,000 eggs per g of faeces; EPG), 7 per cent had moderate infections (1,000-10,000 EPG), and 1 per cent had heavy (greater than 10,000 EPG). Other important intestinal infections found in this community are hookworm, Taenia spp. and Trichuris trichiura with the prevalence of 17.9 per cent, 1.1 per cent and 1.1 per cent respectively.