Long-term efficacy of single-dose oral treatment in schistosomiasis haematobium.

A two-year follow-up was conducted in children who had been the subjects of a six-month double-blind trial in the single-dose treatment of Schistosoma haematobium infection. The trial had assessed therapeutic efficacy of three oral preparations-praziquantel 40 mg/kg, metrifonate 10 mg/kg, and the 'combination' (concurrent niridazole 25 mg/kg and metrifonate 10 mg/kg administration). Reduction in urinary egg excretion remained high up to follow-up at two years, based on a comparison of pre- and post-treatment geometric mean counts-praziquantel 96.9% (n = 96 at six months, 51 at two years); the 'combination' 93.9% (n = 97 at six months, 48 at two years); and metrifonate 90.3% (n = 92 at six months, 49 at two years). The differences in percentage reduction were not significant (p greater than 0.1). However, a significantly greater reduction in egg output was produced by praziquantel (81.7%) and the 'combination' (82.5%) than by metrifonate (54.2%), on comparing pre- and post-treatment arithmetic mean counts (p less than 0.01). A significantly smaller percentage of subjects were excreting greater than or equal to 125 ova/10 ml urine two years after treatment with praziquantel (10.3%), compared to treatment with the 'combination' (25.7%) and metrifonate (35.8%) (p less than 0.01). The cure rate was significantly higher in the praziquantel group (47.4%) compared to the 'combination' (24.7%) and metrifonate (17.4%) groups, for the six to 24-month follow-up period (p less than 0.001). The pattern and level of transmission had contributed to the long-term efficacy recorded in this study.