Efficacy and side-effects of two praziquantel treatments against Schistosoma haematobium infection, among schoolchildren from Cote d'Ivoire

Praziquantel is the current drug of choice for the control of schistosome-attributable morbidity and is likely to remain so for several years. However, as there is concern that schistosomes might develop resistance to the drug, the monitoring of praziquantel's efficacy in different epidemiological settings is recommended. Here, the results of an innovative study of the drug's effectiveness, in an area in Cote d'Ivoire that is highly endemic for Schistosoma haematobium, are reported. Each of the subjects (354 schoolchildren aged 5-15 years) was given two oral doses of praziquantel (each of 40 mg/kg) 4 weeks apart. The numbers of schistosome eggs in urine samples collected over several consecutive days prior to the first and after the second treatment were then determined. High cure and egg reduction 'rates', of 93.0% and 96.6%, respectively, were found. Although mild and transient side-effects were frequently observed after the first treatments, no severe systemic complaints were recorded. When the 20 children who remained egg-positive after the second dose were each given a third dose of praziquantel, 16 (80%) of them responded and became egg-negative. Unfortunately, the schistosome strains infecting the remaining four children could not be investigated in detailed laboratory studies, because of the failure of eggs to hatch. There were therefore no unambiguous signs of resistance to praziquantel in this epidemiological setting. The benefits and disadvantages, compared with single-dose treatments, of administering praziquantel twice within a few weeks are discussed. It is anticipated that this approach might prove efficacious in areas of high infection intensity. The integration of such pharmaceutical measures with other readily available control tools is likely to mitigate the current, intolerable burden of schistosomiasis.