Field trials in the control of Opisthorchis viverrini with an integrated programme in endemic areas of northeast Thailand.

A control programme of opisthorchiasis was carried out for three years in three villages of northeast Thailand in order to compare the effectiveness of two intervention measures. The intervention measures employed were to give praziquantel treatment to all infected people either once (village I) or twice (village II) per year with the integration of regular health education and sanitation improvement. A control village (village III) received no intervention during the study. Sampling of the population in these villages to estimate prevalence, intensity, reinfection and incidence of infection as well as knowledge of opisthorchiasis and number of latrines was performed at 6 monthly intervals throughout the duration of the study. At the initial assessment, there were no significant differences in the prevalence and intensity of infection of villages I and II. Both values were greatly reduced when assessed 6 months after the initiation of treatment, and the decrease in prevalence and intensity of infection did not differ between village I and II. The control village (village III), during the first 2 years, exhibited slight variation in the prevalence and intensity, and these decreased considerably in the third year of the study. The reinfection rate per 6 months in villages I and II was nearly equal. The incidence rate per 6 months in the two treated villages was lower than that of the control village. Marked improvement in knowledge of opisthorchiasis, behavioural changes of eating raw fish and increased numbers of latrines was evident in all of the villages during this study.(ABSTRACT TRUNCATED AT 250 WORDS)