Neurological manifestations in Onchocerca volvulus infection: A review

Abstract

Human onchocerciasis, caused by infection by the filarial nematode Onchocerca volvulus, is a major neglected public health problem that affects millions of people in the endemic regions of sub-Saharan Africa and Latin America. Onchocerciasis is known to be associated with skin and eye disease and more recently, neurological features have been recognized as a major manifestation. Especially the latter poses a severe burden on affected individuals and their families. Although definite studies are awaited, preliminary evidence suggests that neurological disease may include the nodding syndrome, Nakalanga syndrome and epilepsy but to date, the exact pathophysiological mechanisms remain unclear. Currently, the only way to prevent Onchocera volvulus associated disease is through interventions that target the elimination of onchocerciasis through community distribution of ivermectin and larviciding the breeding sites of the Similium or blackfly vector in rivers. In this review, we discuss the epidemiology, potential pathological mechanisms as well as prevention and treatment strategies of onchocerciasis, focusing on the neurological disease.

Keywords: Epilepsy; Neurological features; Onchocerca volvulus.

Fig. 1

This figure is adapted from the WHO and show the worldwide distribution of Onchocerciasis and the countries with ongoing transmission in 2013, http://www.who.int/onchocerciasis/distribution/en/.

Fig. 2

This is an electroencephalographic recording from scalp electrodes of a 15-year-old male Ugandan adolescent with Onchocerca associated epilepsy. He has had symptoms for at least 3 years. The recording shows generalized epileptiform discharges. Recording by Dr Richard Idro.