Onchocerca volvulus is not detected in the cerebrospinal fluid of persons with onchocerciasis-associated epilepsy

Abstract Objectives Epidemiological evidence links onchocerciasis with the development of epilepsy. We aimed to detectOnchocerca volvulus microfilariae or its bacterial endosymbiont, Wolbachia, in the cerebrospinal fluid (CSF) of persons with onchocerciasis-associated epilepsy (OAE). Methods Thirteen persons with OAE andO. volvulus skin snip densities of >80 microfilatiae were recruited in Maridi County (South Sudan), and their CSF obtained. Cytospin centrifuged preparations of CSF were examined by light microscopy for presence of O. volvulus microfilariae. DNA was extracted from CSF to detect O. volvulus (O-150 repeat) by quantitative real-time PCR, and Wolbachia (FtsZ gene) by standard PCR. To further investigate if CSF from onchocerciasis-infected participants could induce seizures, 3- and 7-days old zebrafish larvae were injected with the CSF intracardially and intraperitoneally, respectively. For other zebrafish larvae, CSF was added directly to the larval medium. Results No microfilariae, parasite orWolbachia DNA were detected in any of the CSF samples by light microscopy or PCR, respectively. All zebrafish survived the procedures and none developed seizures. Conclusion The absence of O. volvulus in CSF suggests that OAE is likely not caused by direct parasite invasion into the central nervous system, but by another phenomenon triggered by O. volvulus infection.