Prevalence and Intensity of Onchocerca volvulus Infection in Kura L.G.A, Kano State, Nigeria: Implication for Elimination Efforts

Abstract

Background:
Onchocerciasis remains endemic in many rural communities in Nigeria despite decades of mass drug administration (MDA) with ivermectin. Accurate prevalence data at the community level are essential for tracking progress toward elimination. However, many endemic areas lack recent parasitological assessments.
Objective:
To determine the current prevalence and intensity of Onchocerca volvulus infection among residents of Kura LGA in Kano State, Nigeria, and to evaluate whether transmission persists at levels above the World Health Organization (WHO) elimination threshold.
Methodology:
This was a secondary analysis of cross-sectional survey data collected by the National Primary Health Care Development Agency (NPHCDA) in collaboration with the State Ministry of Health (MoH), and ESPEN from 2020 to 2024. Records of 400 participants aged ≥ 5 years from 10 onchocerciasis-endemic communities in Kura Local Government who are predominantly subsistence farmers were analysed. Microfilariae (Mf) prevalence and geometric mean intensity were determined from skin snip results. Prevalence was compared across age groups and sex using Chi-square tests.
Key Results:
A total of 400 de-identified individual records were extracted from the government dataset and included in this analysis, with participants (mean age 38.2 ± 15.4 years; 52% female) enrolled. The overall prevalence of O. volvulus microfilariae was 31.5% (95% Cl: 27.0-36.2). prevalence was highest among males (37.2%; 95% CI: 30.6 – 44.2) compared to females (26.3%; 95% CI: 20.8 – 32.7), with a difference of 10.9 percentage points, and in the age group 30-44 years (41.2%). Notably, 18.3% of children aged 5-14 years tested positive, indicating ongoing transmission. Only 62% of participants reported taking ivermectin within the last 12 months.
Conclusion:
Onchocerciasis prevalence in Kura LGA remains above the WHO elimination threshold (<1% in children). Suboptimal MDA coverage and persistent transmission in younger age groups call for enhanced community-directed treatment strategies and regular surveillance.