Human soil-transmitted helminths: implications of mass drug administration.

PURPOSE OF REVIEW With the London Declaration on neglected tropical disease (NTD), we are entering a new era of combating NTDs. However, the worldwide prospects of increased mass drug administration (MDA) treatments warrant caution on the development of anthelmintic resistance. In this review, we discuss the practical implications of MDA programs on the development of anthelmintic resistance in human soil-transmitted helminths (STH). RECENT FINDINGS There is poor evidence of anthelmintic resistance in human STH. Moreover, there is presumptive evidence that the refugia in MDA programs to control human STH is currently large, suggesting that the development of anthelmintic resistance in STH will be slow or may not occur. It remains unclear whether the current MDA strategy to control STH will sufficiently delay or prevent the development of anthelmintic resistance. First, differences in efficacy across and within STH species, and seasonal transmission of STH have not yet been considered. Second, any surveillance system to monitor drug efficacy is lacking. Finally, there is still no agreed strategy on how to deal with anthelmintic resistance once it emerges. SUMMARY Although anthelmintic resistance in human STH is currently of limited concern, various actions should be put in place for its delay and monitoring, and strategies should be developed in case anthelmintic resistance occurs.