Evolution of operational research studies and development of a national control strategy against intestinal helminths in Pemba Island, 1988–92

Intestinal helminthic infections in Pemba Island, United Republic of Tanzania, have been perceived as a public health problem for many decades. School surveys in 1988 and 1992 and a community survey in 1991 were carried out to assess the distribution of prevalence and the intensity of these infections and to define the most effective strategy for control. The prevalence of helminthic infections exceeded 85% in all the surveys, and intensity was moderate. These studies identified the high-risk age groups, high transmission areas for different parasites, and the most cost-effective anthelminthic drug. This work is an example of how existing health systems and simple analytical tools may be used to generate useful data which, in turn, are used to define suitable intervention strategies. As a result, the Ministry of Health of Zanzibar has developed a national plan for the integrated control of intestinal helminths. This plan envisages periodic mass treatment of school-age children with mebendazole (500 mg, single dose, every four months) for the control of morbidity due to Ascaris, Trichuris, and hookworms.