The Prevalence and Distribution of Human Onchocerciasis in Two Senatorial Districts in Ebonyi State, Nigeria

Abstract

There has been a recent increase in the number of human Onchocerciasis cases in hospitals in Ebonyi Central. This study therefore sets out to determine the prevalence of the disease in Ebonyi North and Central Senatorial Zones of Ebonyi State as well as determine the age groups and sex most affected. Methods:This study was carried out in Ebonyi North and Central Senatorial Zones of Ebonyi State between January 2011 and April 2012, among subjects of 20-59 years. Diagnosis was by skin examination for onchocercal lesions, ocular examination for ocular lesion and parasitological examination for the presence of microfilariae of Onchocerca volvulus in skin biopsies and adult filariae in excised nodules. Results: Out of the 250 persons randomly examined in each zone, 82 (32.8%) persons in Ebonyi Central zone comprising of 60 (38.7%) males and 22 (23.1%) females were found positive for Onchocerca volvulus while 73 (29.2%) persons in Ebonyi North Zone comprising 48 (32.0%) males and 25 (25.0%) females. Chi-square test shows that male subjects had significantly higher diseases prevalence (p < 0.05) than their female counterparts in the two zones but combined prevalence among male and female do not differ significantly in the two zones. The age group most affected was 50-59 years with the prevalence of 40.0% in Ebonyi Central and 38.6% in Ebonyi North Zones. Out of the 155 (30.8%) persons infected in the two zones, 28 (5.6%) males and 14 (2.8%) females had Onchocercal skin lesions, 57 (11.4%) males and 22 (4.4%) females had low vision. Partial blindness was observed in 16 (3.2%) males and 8 (1.6%) females. However, 7 (1.4%) males and 3 (0.6%) females had complete blindness. Farmers were mostly affected than any other occupational group. Conclusion: The findings obtained from this work suggested that Ebonyi Central and North Senatorial Zones are Onchocerciasis hypo-endemic Zones having the prevalence rate of 32.8% and 29.2% respectively. Sex, age and occupation are related to Onchocerciasis infections in both Zones. Males are more infected than females. Massive distribution of insecticides to destroy the vector Simulium damnosum (black fly), provision of adequate antiflarial drugs - ivermectin and mass health education targeted on preventive measures are highly recommended.