Onchocerciasis-Associated Epilepsy, an Explorative Case-control Study

Epilepsy, Onchocercal Subcutaneous Nodule, Virus

Onchocerciasis, Epilepsy, metagenomics, South Sudan, Pathogenesis

This is an exploratory case control study with the aim to compare the Onchocerca volvulus virome between persons with onchocerciasis-associated epilepsy (OAE) and persons with onchocerciasis but without epilepsy. The main question we want to address is: Is there a virus contained in the O. volulus worm that may have a pathogenic role in causing OAE. In Maridi County, South Sudan, 20 persons with OAE with onchocerciasis nodules, and 20 age- and village-matched controls without OAE will be enrolled in a nodulectomy study.The adult O. volvulus worms will be extracted from the nodules and a viral metagenomic study of the worms. The O. volvulus virome of persons with and without OAE will be compared.

A high prevalence of onchocerciasis-associated epilepsy (OAE) has been observed in onchocerciasis-endemic areas with high ongoing Onchocerca volvulus transmission. However, the pathogenesis of OAE remains to be elucidated. We hypothesise that the O. volvulus virome could be involved in inducing epilepsy. With this study, we aim to describe the O. volvulus virome and identify possible viruses linked to OAE. In Maridi County, South Sudan, 20 persons with OAE with onchocerciasis nodules, and 20 age- and village-matched controls without OAE will be enrolled in the study. For each study participant, two skin snips at the iliac crest will be obtained to collect O. volvulus microfilaria, and one nodulectomy will be performed to obtain adult worms. A viral metagenomic study will be conducted on microfilariae and adult worms, and the O. volvulus virome of persons with and without OAE will be compared. Moreover, the prevalence, numbers and localisation of onchocerciasis nodules in persons with and without OAE in villages with a high prevalence of epilepsy in Maridi will be described.

South Sudan