Important entomological events in the history of onchocerciasis ('river blindness').

Abstract

This article reviews the major events that entomology has played, and still plays, in the history of onchocerciasis ('river blindness') from life-cycle discovery to the current global goal of elimination of parasite transmission in all endemic areas. The identified events include the various attempts to implement successful vector control, the important introduction of the microfilaricide ivermectin and the new improvements in laboratory-based techniques to identify infected blackflies and refine onchocerciasis epidemiology and programme monitoring. These scientific events are paralleled with the development of a series of increasingly ambitious public health targets, first to reduce blindness due to this infection, then to reduce the prevalence of all the clinical symptoms (ocular and dermatological disease) and, finally, in more recent times, to interrupt actual transmission of the parasite. Five major areas of onchocerciasis-related entomology (i.e. the effects of fly biting; vector competence and migration; epidemiology; vector control; and management of elimination programmes) illustrate the importance of entomology to achieving success in eliminating the transmission of Onchocerca volvulus; success that has already been achieved in four countries in Latin America and now in one country in Africa (Niger, 2024), the continent where the vast majority of remaining endemicity is found.