Epidemiology of soil-transmitted helminths in the western region of Bhutan.

In May 2003, a survey was conducted in the western region of Bhutan to assess the prevalence and intensity of soil-transmitted helminth (STH) infections after 15 years of school deworming in the country. Five schools were randomly selected in the region and 266 schoolchildren were examined. Stool samples were collected from each child as well as nutritional indicators and general information on each school. The survey found a cumulative prevalence of 16.5% STH (4.8% in schools treated in the last three months and 24% in the untreated schools). An unexpected finding was that the tapeworm infection rate of 6.7%. These results indicate a high reinfection rate in this area. WHO recommends a 50% prevalence as the threshold for the establishment of community intervention. However, in our view, Bhutan needs to continue its deworming program because the present, relatively low, prevalence level was found despite a long period of intervention; an interruption of the control activities will result in a return to very high levels of prevalence and intensity of infection.