Onchocerciasis-associated epilepsy: an update and future perspectives. Issue 2 (February 2023)

• Record Type: Journal Article
• Authors: Hadermann, Amber; Amaral, Luis-Jorge; Van Cutsem, Gilles; Siewe Fodjo, Joseph N.; Colebunders, Robert
• Is Part Of: Trends in parasitology. Volume 39:Issue 2(2023)
• Page Start: 126
• Page End: 138
• Publication Date: 2023-02
• Subjects: onchocerciasis -- epilepsy -- nodding syndrome -- ivermectin -- pathogenesis -- cerebrospinal fluid; Parasitology -- Periodicals; Parasitology -- Periodicals; Biology -- Periodicals; Parasitology; Biology; Parasitologie -- Périodiques; Online resources; 571.999
• DOI: 10.1016/j.pt.2022.11.010
• Languages: English
• ISSNs: 1471-4922

Abstract

Highlights: There is strong epidemiological evidence that onchocerciasis directly or indirectly induces epilepsy. The risk for children to develop epilepsy in onchocerciasis-endemic regions increases with their Onchocerca volvulus microfilarial (mf) load. During the pre-ivermectin era, O. volvulus mf were observed in cerebrospinal fluid (CSF) and their levels increased following the administration of diethylcarbamazine (DEC). Fever-induced increased blood–brain barrier permeability could allow the passage of mf through the choroid plexus into the brain. Strengthening onchocerciasis elimination programmes via optimal ivermectin coverage and vector control in areas with high ongoing transmission reduces the incidence of epilepsy, including nodding syndrome. Abstract: Onchocerciasis-associated epilepsy (OAE) is an important neglected public health problem in areas with high ongoing onchocerciasis transmission. The risk that children in such areas develop epilepsy is related to their Onchocerca volvulus microfilarial (mf) load. Before the implementation of mass treatment with ivermectin, microfilariae were detected in cerebrospinal fluid (CSF). More recently, neither O. volvulus microfilariae nor DNA were detected in CSF or brain tissue; however, these samples were obtained years after seizure onset. It is possible that during fever-induced increased blood–brain barrier permeability, microfilariae enter the brain and, upon dying, cause an inflammatory reaction inducing seizures. Including OAE in the onchocerciasis disease burden estimation may mobilise extra resources for onchocerciasis disease elimination and treatment/care of OAE-affected persons/families.