Single Versus Multiple Dose Ivermectin Regimen in Onchocerciasis-infected Persons with Epilepsy Treated with Phenobarbital: A Randomized Clinical Trial in the Democratic Republic of Congo

Background: There is anecdotal evidence that ivermectin may decrease seizure frequency in Onchocerca volvulus-infected persons with epilepsy (PWE). Methods: In October 2017, a 12-month clinical trial was initiated in rural Democratic Republic of Congo. PWE with onchocerciasis-associated epilepsy experiencing ≥2 seizures/month were randomly allocated to receive, over a one-year period, ivermectin once or thrice (group 1), while other onchocerciasis-infected PWE (OIPWE) were randomized to ivermectin twice or thrice (group 2). All participants also received anti-epileptic drugs. Data was analyzed using multiple logistic regression. Results: We enrolled 197 participants. In an intent-to-treat analysis (data from group 1 and 2 combined), seizure freedom was more likely among OIPWE treated with ivermectin thrice (OR: 5.087, 95% CI: 1.378–19.749; p = 0.018) and twice (OR: 2.471, 95% CI: 0.944–6.769; p = 0.075) than in those treated once. Similarly, >50% seizure reduction was more likely among those treated with ivermectin twice (OR: 4.469, 95% CI: 1.250–16.620) and thrice (OR: 2.693, 95% CI: 1.077–6.998). Absence of microfilariae during the last 4 months increased the odds of seizure freedom (p = 0.027). Conclusions: Increasing the number of ivermectin treatments was found to suppress both microfilarial density and seizure frequency in OIPWE, suggesting that O. volvulus infection plays an etiological role in causing seizures.