Post-Evaluation of Mass Drug Administration Against Onchocerciasis in Two Communities in Akwanga Local Government Area, Nasarawa State, Nigeria

Background:

In sub-Saharan Africa, onchocerciasis (river blindness), which is caused by Onchocerca volvulus and spread by Simulium blackflies, is still a neglected tropical illness. In two communities in Akwanga LGA, Nasarawa State, Nigeria, this study assessed the effects of mass drug administration (MDA) on onchocerciasis prevalence, transmission, and control.

Methodology:

A cross-sectional study was carried out in the two communities between July and November of 2024. Capillary blood samples were collected from 97 participants (Ungwan Zaria: n=53; Ungwan Habu: n=44). Thick and thin blood smears were Giemsa-stained (10%) and examined microscopically for microfilariae. Hematological parameters (hematocrit (HCT), white blood cell count (WBC), neutrophils, lymphocytes, monocytes, eosinophils, basophils, red blood cell count (RBC), hemoglobin) were analyzed. OV16 ELISA confirmed elimination status.

Results:

Microfilariae were not detected in any of the samples (0.0% prevalence; 95% CI: 0.0-3.7%). ELISA for OV-16 showed no O. volvulus antigens. Hematological analysis revealed significant inter-community variations (p<0.05) with Ungwan Zaria having higher HCT (41%), WBC (3417±358.36 cells/μL) and hemoglobin (13.24±0.901 g/dL) than Ungwan Habu (HCT: 32%; hemoglobin: 1.20±0.677 g/dL) indicating a high prevalence of anemia. MDA adherence was 100% following five annual treatment rounds.

Conclusion:

Sustained MDA effectively interrupted onchocerciasis transmission in both communities. However, significant hematological disparities -particularly severe anemia in Ungwan Habu-warrant integrated nutritional and immunological interventions. Post-elimination surveillance remains critical to prevent reintroduction and ensure sustained elimination gains.