Scales modified for dose determination in population-based chemotherapy.

Integration of schistosomiasis control into primary health care services in The Gambia required semiliterate health workers to administer praziquantel and metrifonate to the community in doses based on weight. Special scales to weigh people with a direct readout in the form of numbers of tablets obviated the need to read figures or make calculations at the scene. The scales were used with a simple record system. Coverage of up to 97% was achieved with single dose praziquantel; for three doses of metrifonate spread over 2 months, coverage reached 82.4%. The tablet scale was easy to devise and fit to commercial scales.