The rational use of antischistosomal drugs in schistosomiasis control

The paper examines the available antischistosomal drugs in Zimbabwe and the use of population-based chemotherapy as an effective strategy of morbidity reduction in schistosomiasis control. The problems of poor drug efficacy and side-effects that were associated with earlier antischistosomal drugs have largely been overcome with the advent of recent, safe and effective oral drugs. The main constraints of population-based chemotherapy are the costs of drug procurement, transport and the logistics of delivery. In highly endemic areas, screening for infection may not be necessary and following pilot surveys mass chemotherapy can be carried out. Nevertheless, anecdotal and unverified reports suggest that mass chemotherapy may result in lightly infected individuals losing their residual immunity and risk heavy reinfection. To lower costs of the drugs and reduce organizational problems of delivery it may be preferable to target treatment at high risk groups. These groups include certain age classes with peak prevalence and intensity of infection and those predisposed to get heavy infections. Treatment prevents the development of overt disease in these high risk groups and also significantly reduces contamination and consequently transmission. However, chemotherapy only results in temporary relief and its impact requires to be sustained by parallel and long-lasting interventions that include improved sanitation, better water supplies and health education. Suggestions are made on how to train and utilize community and public health workers for such control programmes.