Seroprevalence and Risk Factors Associated with Onchocerciasis among Rural Farmers in Kagarko Local Government Area, Kaduna State, Nigeria

Abstract

Onchocerciasis remains a public health concern in rural farming communities in sub-Saharan Africa, with a significant health impact. This community-based cross-sectional study assessed the prevalence and risk factors associated with onchocerciasis among farmers in three communities, Kubacha, Kenyi, and Kagarko, in Kagarko Local Government Area, Kaduna State, Nigeria. A total of 400 farmers were sampled using structured questionnaires and serological testing with the SD Bioline Onchocerciasis IgG4 rapid test kit. The overall prevalence of onchocerciasis was 3.8%, with Kubacha recording the highest prevalence at 5.4% (8/147), followed by Kenyi at 2.8% (3/106) and Kagarko at 2.7% (4/147). Male farmers showed a higher seropositivity rate of 5.6% (11/198) compared to females at 2.0% (4/202) (Odds Ratio [OR] = 0.279; 95% CI: 0.083-0.943; p = 0.060). Educational attainment was significantly associated with infection; farmers with only FSLC education had a prevalence of 7.7% (11/143) compared to 1.8% (3/166) in those with WASSCE/GCE/NECO, with a statistically significant difference (p = 0.034). Regarding risk factors, 86.0% of respondents reported experiencing blackfly bites, with a seroprevalence of 4.4% (15/344) among those exposed compared to 0% among those not exposed, although this difference was not statistically significant (p = 0.114). Proximity to blackfly breeding sites was reported by 75% of participants; seroprevalence among this group was 4.2% versus 2.2% in those without proximity (p = 0.323). Notably, long-term ivermectin use (>15 years) was associated with significantly lower seropositivity (1.2%) compared to non-users (5.4%) (χ2 = 4.695; p = 0.033). However, routine annual intake of ivermectin did not show a statistically significant difference in prevalence (2.1% vs 4.6%; p = 0.208). These findings demonstrate a moderate prevalence of onchocerciasis among farmers in Kagarko LGA, with education level and long-term ivermectin use significantly influencing infection rate. We recommend that the government should make ivermectin drugs constantly available and accessible to the people, most especially the residents of Kagarko LGA of Kaduna state, Nigeria.