Impact of a Bi-annual Community-directed Treatment With Ivermectin Programme on the Incidence of Epilepsy in an Onchocerciasis-endemic Area of Mahenge, Tanzania: a Population-based Prospective Study

Onchocerciasis is a neglected tropical disease associated with epilepsy, particularly in areas of high Onchocerciasis volvulus transmission. Onchocerciasis-associated epilepsy is characterised by seizures that start between the ages of five to 18 years. The tropical disease can be controlled through community-directed treatment with ivermectin (CDTi). Mahenge, in Tanzania, had a high prevalence of onchocerciasis and epilepsy despite more than 20 years of annual CDTi. Hence, the Tanzanian Neglected Tropical Diseases Control Programme has switched from annual to bi-annually CDTi since 2019. After this switch, the CDTi coverage increased and was sustained in both ivermectin rounds in 2021, and the number of new epilepsy cases decreased. The latter were persons who did not take ivermectin the year they had the first seizures. Hence, all ivermectin-eligible children at risk of onchocerciasis should take ivermectin at least annually. Overall, increasing the frequency and coverage of the CDTi programme should be considered in onchocerciasis-endemic areas with a high prevalence of epilepsy.