Cure rate is not a valid indicator for assessing drug efficacy and impact of preventive chemotherapy interventions against schistosomiasis and soil-transmitted helminthiasis

Abstract

Every year in endemic countries, several million individuals are given anthelminthic drugs in the context of preventive chemotherapy programmes for morbidity control of schistosomiasis and soil-transmitted helminthiasis. The capacity to evaluate accurately the efficacy of the drugs used as well as the health impact produced by treatment is of utmost importance for appropriate planning and implementation of these interventions. Cure rate is an indicator of drug efficacy that was originally developed for assessing the clinical efficacy of antibiotics on selected bacterial diseases. Over time, this indicator has also been widely applied to anthelminthic drugs and consequently used to monitor and evaluate preventive chemotherapy interventions. In the author's opinion, however, measurement of cure rate provides information of limited usefulness in the context of helminth control programmes. The present article analyses the peculiarities of helminth infections and those of the drugs used in preventive chemotherapy, explaining the reasons why the cure rate is not an adequate indicator in this specific public health context.