Onchocerciasis: neurological involvement

Abstract

Onchocerciasis or “river blindness” is an endemic parasitic disease caused by the filarial nematode Onchocerca volvulus, transmitted by a blackfly of the genius Simulium. It has a serious public health impact in 39 countries worldwide, particularly in sub-Saharan Africa where the burden is highest. The neurological involvement in onchocerciasis includes both the peripheral and central nervous system. The clinical manifestations constitute a spectrum of disorders spanning from the very stigmatizing onchocercal itch to optic nerve disease, epilepsy and post-treatment encephalopathy. There has been significant progress in recent years in the understanding of the neuroscience of itching in general, with the discovery of itch-specific neurons and their pathways. However, the exact mechanisms of the onchocercal itch, as well as the pathogenesis of optic nerve disease, epilepsy or encephalopathy are yet to be fully understood. Nevertheless, the relatively new concepts such as “pruritoception” on one hand, and “river epilepsy” on the other hand, may become future active areas of neuroscience research. This may lead eventually not only to novel basic and translational knowledge but also to drug development and improved control strategies for onchocerciasis and associated nervous system complications.