The Efficacy of a Single-dose Mebendazole Against Soil-transmitted Helminths in School Children

Primary objective:

Following obtaining informed consent, schoolchildren in the target age range group will be recruited and asked to provide a recent stool sample (an interval of less than 4 hours) that will be processed to determine the Faecal Egg Count (FEC) for each Soil-Transmitted Helminths (STH) present. For the initial sampling the aim is to enroll at least 250 infected children for at least one of the Soil-Transmitted Helminths (STH). This sample size was selected based on statistical analysis of study power, using random simulations of correlated over-dispersed Faecal Egg Count data reflecting the variance-covariance structure in a selection of real Faecal Egg Count (FEC) data sets. This analysis suggested that a sample size of up to 200 individuals (α = 0.05, power = 80%) was required to detect a 10 percentage point drop from a null efficacy of ~ 80% (mean percentage FEC ∆ per individual) over a wide range of infection scenarios. Standard power analyses for proportions also indicated that the detection of a ~10 percentage point drop from a null cure rate required sample sizes up to 200 (the largest samples being required to detect departures from null efficacies of around 50%). Given an anticipated non-compliance rate of 25%, a sample of 250 infected subjects was therefore considered necessary at each study site.

All children providing stool samples will be treated with mebendazole (MBZ) single table of 500mg under supervision (chewing + water). The mebendazole (MBZ) will be provided (free) by the coordinating group. Seven up to fourteen days (maximum interval) after treatment a second faecal sample will be collected from the children to determine again FEC. Subjects who are unable to provide a stool sample at follow-up, or who are experiencing a severe concurrent medical condition or have diarrhea at time of the first sampling, will be excluded from the study.

Secondary objectives:

In 5 study sites, faecal samples of 100 infected subjects should be preserved before treatment with mebendazole (MBZ) in one tube (1 gram in 10 ml 70% ethanol). Samples of the same children should be also preserved again in one tube (1 gram in 10 ml 70% ethanol) after treatment. Samples have be send to the Laboratory of Parasitology, Ghent University.