EFFECT OF BI-ANNUAL COMMUNITY-DIRECTED DISTRIBUTION WITH IVERMECTIN (CDTI) AND A COMMUNITY-BASED AWARENESS PROGRAMME ON THE INCIDENCE OF ONCHOCERCIASIS-ASSOCIATED EPILEPSY IN MAHENGE, TANZANIA.

Abstract

Intro: Despite 25 years of annual CDTI in Mahenge, Tanzania, the prevalence of onchocerciasis and epilepsy remained high in certain rural villages. In Uganda, bi-annual ivermectin distribution and larviciding rivers prevented new cases of onchocerciasis-associated epilepsy (OAE), including nodding syndrome (NS). In 2019, the Tanzanian government implemented a bi-annual CDTI programme in Mahenge. Additionally, we introduced a community-based awareness programme on epilepsy and onchocerciasis in four rural villages with high epilepsy and onchocerciasis prevalence (Mdindo, Msogezi, Mzelezi and Sali). We evaluated the impact of bi-annual CDTI and this community-based awareness programme on the incidence of epilepsy in these villages. Methods: We conducted pre- and post-intervention epilepsy surveys in 2017/2018 and 2021/2022, respectively. Each survey included door-to-door visits to screen all household members for suspected cases of epilepsy using a validated questionnaire and the examination of the suspected cases by a trained medical doctor to confirm the diagnosis. The annual incidence of epilepsy was presented as the number of new epilepsy cases per 100,000 persons-years and was calculated as the number of individuals who developed their first seizures during the five years before the survey divided by five times the total population included in the survey. Findings: In 2017/2018, 182 of the 5,444 (3.3%) surveyed individuals were confirmed to have epilepsy; 77.9% met the criteria of OAE, and 12.7% reported a history of nodding seizures. The incidence of epilepsy declined from 123 (95%CI: 88.2-173.9) in 2017/2018 to 34.1 (95%CI: 17.9-64.8) in 2021/2022, while that of NS declined from 26.3 (95%CI: 12.7-54.2) to 11.4 (95%CI: 3.9-33.4) in the same period. Conclusion: Bi-annual CDTI and a community-based awareness programme decreased the incidence of OAE in the rural study villages. This programme should be scaled up in Mahenge to prevent children from developing OAE in other rural villages with high epilepsy incidence.