Sequential analysis of helminth egg output in human stool samples following albendazole and praziquantel administration

Abstract Large-scale administration of anthelminthic drugs currently is the most widely used intervention for controlling morbidity due to schistosomiasis and soil-transmitted helminthiasis. An important issue is drug efficacy monitoring. However, the optimal time points post-treatment for assessing the efficacy of praziquantel against Schistosoma mansoni and albendazole against hookworm infections are not known. Forty-nine schoolchildren infected with S. mansoni and 52 infected with hookworm were treated with a single oral dose of praziquantel (40 mg/kg) and albendazole (400 mg), respectively. Stool samples were collected on 19 occasions over a 44-day post-treatment follow-up period, and two Kato-Katz thick smears per sample were examined at each time point. Both the mean egg counts and observed cure rates varied depending on the time point post-treatment. The highest reduction in the geometric mean egg counts (>97%) and the highest observed cure rate (>97%) of S. mansoni infections were found 15–20 days after praziquantel administration. Among the hookworm-infected children, egg counts decreased rapidly within the first week after albendazole administration (>95%), whereas infection rates showed high and heterogeneous (45.0–71.2%) levels at later time points. Both praziquantel and albendazole were highly efficacious in reducing the overall egg burden of S. mansoni and hookworm, respectively. We suggest that 15–20 days post-treatment is the most appropriate time point for efficacy evaluation of praziquantel against S. mansoni . Although no clear conclusion can be drawn for the optimal timing of efficacy evaluation of albendazole against hookworm, a 2–3-week time frame seems a reasonable compromise. This is justified on logistical grounds (i.e. collection of stool samples only once) and growing emphasis on integrating the control of schistosomiasis and soil-transmitted helminthiasis, including drug efficacy monitoring.