Onchocerciasis associated epilepsy in South Sudan, an epidemiological, social and entomological study

Onchocerciasis, commonly known as river blindness, is a neglected tropical disease caused by nematode parasite Onchocerca volvulus. It is transmitted to humans through repeated bites of female black flies. Onchocerciasis is a known cause of eye and skin disease, posing significant socioeconomic challenges to the communities affected. In recent years there has been a surge in reports detailing an increase in epilepsy cases including nodding syndrome in onchocerciasis endemic areas where the onchocerciasis elimination measures are either sub-optimally functioning or nonexistent. Recent epidemiological studies in countries in Central and East Africa suggest onchocerciasis can induce epilepsy. While substantial epidemiological evidence indicates an association between epilepsy and onchocerciasis, the precise pathophysiological mechanism by which the O. volvulus parasite induces the disease has remained unidentified. Many retrospective studies from East Africa suggest that strengthening the onchocerciasis elimination programme could prevent onchocerciasis associated epilepsy (OAE) including nodding syndrome. This PhD project investigated the burden of OAE including nodding syndrome in onchocerciasis endemic villages in Western Equatorial State, South Sudan. It also investigated the effect of strengthening onchocerciasis elimination programme on the incidence of epilepsy including nodding syndrome. The first, and second study was conducted in onchocerciasis-endemic villages in Mvolo, and Mundri in June 2020, and July 2021 respectively investigating the epidemiology of epilepsy in onchocerciasis endemic areas. The third and fourth study was conducted in 2020 in Maridi and Mundri. To investigate the beliefs and perceptions about epilepsy and its treatment among the communities in the endemic areas, and to investigate the epilepsy treatment and care cost for people living with epilepsy and their families. The fifth study was conducted in Maridi in period 2019 to 2021. In this study we evaluated the impacted of a community directed vector control intervention” Slash and Clear’’ on the reduction of the blackfly population in villages around the Maridi dam, the blackfly breeding site The sixth study was conducted in March 2022 in Maridi County to evaluate the impact of bi-annual CDTI and a community-based vector control method on onchocerciasis transmission and the incidence of OAE in Maridi County. This PhD study provides additional evidence for the association between onchocerciasis and epilepsy for strengthening onchocerciasis elimination measures to reduce the incidence of epilepsy including nodding syndrome in onchocerciasis endemic areas.