Comparative trials of regimes for the treatment of urinary schistosomiasis in The Gambia.

Alternative regimes for the treatment of Schistosoma haematobium infection were compared in two trials. Praziquantel at a dose of 40 mg kg-1 appeared to cure 63% of a random sample of heavily infected subjects; significantly more than the 18% cured by three fortnightly doses of metrifonate at 10 mg kg-1. However, praziquantel led to a greater incidence of mild, transient side-effects. A single dose of metrifonate was found to be an inadequate treatment in the same group of subjects as it left 53% with an egg count of at least 100 ova/10 ml. A combination of 10 mg kg-1 of metrifonate and 25 mg kg-1 of niridazole had a similar effect to that of a single dose of metrifonate alone and it had more side-effects. Reduced doses of praziquantel had less effect on egg counts than the standard regime, but the difference was not significant in the case of 20 mg kg-1. Although a combination of metrifonate and praziquantel, each at 10 mg kg-1, had a greater effect than either constituent alone, the difference was not significant. Factors affecting the choice of drug for use in mass treatment of urinary schistosomiasis in The Gambia are discussed. The present findings suggest that the standard regime of praziquantel should be used or, if this is not possible, a three-dose metrifonate regime.