Baseline characterization of epilepsy in an onchocerciasis endemic area of the Democratic Republic of Congo

Increased epilepsy prevalence is reported in onchocerciasis (OC) endemic areas and is associated with the occurrence of distinct syndromes such as nodding disease and Nakalanga syndrome. To date, a causal relationship between OC and epilepsy is still a matter of controversy. We conducted a case-control study of participants with epilepsy and age- and gender-matched presumably healthy controls to elucidate the relationships between OC and epilepsy and explore the role of inflammation and growth factors in an OC endemic area in the Democratic Republic of Congo (DRC). Eighty-two participants with epilepsy (mean age ± SD: 23.2 ± 8.7 years) and 27 controls (mean age ± SD: 22.3 ± 12.0 years) underwent snip skin biopsies to determine Onchocerca volvulus infection status. Serum concentrations of cytokines, chemokines, and growth factors were measured using a Luminex Multiplex Assay kit. Children <19 years of age underwent neurocognitive assessments using the Kaufman Assessment Battery for Children, 2^nd edition (KABC-II). Overall, epilepsy was associated with OC (OR = 4.51, z = 3.11, p = 0.0019), and children with OC were more likely to be severely stunted (OR = 11.67, z = 2.62, p = 0.0087). The relationship between epilepsy and OC was no longer significant (z = 1.27, p = 0.20) when stunting was included as a correcting covariate. Epilepsy was associated with poor KABC-II test scores, high serum levels of IL-17, and low levels of IL-1RA, IL-8, and EGF. KABC-II testing scores correlated with serum levels of IL-10, MCP-1 and HGF. Familial history of epilepsy occurred frequently. Future studies should consider cytokines and/or growth factors when assessing susceptibility to epilepsy in OC endemic areas. Additional investigations, preferentially in low-prevalence OC areas, may provide further insights into the concept, risk, and burden of river epilepsy.