Novel Insights in the Fecal Egg Count Reduction Test for Monitoring Drug Efficacy against Soil-Transmitted Helminths in Large-Scale Treatment Programs

摘要

The reduction in number of eggs excreted in stools after drug administration is a primary parameter to monitor the efficacy of drugs against parasitic worms. Guidelines on how to perform such a fecal egg count reduction test (FECRT) are provided by the World Health Organization. However, it remains unclear to which extent these guidelines are cost-effective. We, therefore, performed a simulation study in which the FECRT was performed under varying conditions to determine the critical values for sample size, the detection limit of the fecal egg count (FEC) method, mean baseline FEC, and variation of FEC across host population that allow for conclusive FECRT results. The results revealed that a reliable monitoring system demands a sample size of 200 subjects and that in some cases FECRT results may be thwarted by low mean baseline FEC. For this sample size, the detection of the FEC method or the variation of FEC across the host population did not affect the FECRT results. Our findings underscore that the current guidelines are not cost-effective, demanding too much financial and technical resources. We, therefore, propose novel guidelines to support future monitoring programs.