Side benefits of mass drug administration for lymphatic filariasis on Strongyloides stercoralis prevalence on Pemba Island, Tanzania

Strongyloides stercoralis, although endemic in many countries, is not included in helminth control programs. Few data are available on the prevalence and morbidity linked to this infection. We compared data from two studies conducted in 1998 and 2013 on Pemba Island, Tanzania, involving 525 and 509 schoolchildren, respectively. In 1998, the diagnostic method used was Harada Mori, whereas in 2013 diagnosis was made by both Koga agar plate and Baermann methods. The prevalence registered was 41% in 1998 and 7% in 2013. This data suggest that the prevalence of S. stercoralis on Pemba was significantly reduced 7 years after the last ivermectin administration for preventive chemotherapy and underlines the importance and impact of large-scale preventive chemotherapy, which often goes beyond its actual target. Preventive chemotherapy with ivermectin should be recommended in areas where S. stercoralis is endemic.