RESUMO
A clinical field trial of praziquantel was carried out in Nong Ranya Village, Amphoe Ban Phai, Khon Kaen Province, with a population of 309 individuals, and 94% prevalence rate of opisthorchiasis. A mass treatment was carried out using a single dose of praziquantel at 40 mg per kg body weight. Acceptance for treatment was 91%. Follow-up stool examinations performed on days 14 and 60 gave prevalence rates of 20.5% and 22.2% respectively. Side effects including dizziness, headache, abdominal discomfort, nausea, vomiting, diarrhoea, lassitude, arthralgia, sleepiness, cramps and hot sensation were the complaints from 80% of adults and 40% of children. All of these were mild and transient except in one adult female who had severe diarrhoea and required intravenous fluid infusion.