Abstract
Like horses, humans are dead-end hosts and are susceptible to West Nile virus (WNV) infection, which is transmitted through the bite of competent mosquito vectors. We therefore hypothesised that the horse grooms that daily manage polo horses in Lagos and Ibadan, southwest Nigeria would have serologic evidence of exposure to this virus. Blood samples were aseptically collected from 13 and 12 apparently healthy, adult male horse grooms in Onosa horse ranch, Lagos and Eleyele Polo club, Ibadan, respectively. Sera from the samples were tested for the presence of WNV-specific antibodies using ELISA and data obtained were analysed using Chi-square and t-tests. The age of the participants ranged from 18.0 - 46.0 years (mean age: 31.1 years), with mean ages of grooms in Lagos and Ibadan being comparable (p=0.34). An overall WNV antibody prevalence rate of 56.0% (95% CI: 36.5 – 75.5%) was observed among the 25 grooms. While the 46.2% and 66.7% prevalence rates for Lagos and Ibadan grooms respectively were comparable (p=0.30), the latter had more than twice likelihood (odds ratio = 2.4) of being seropositive than the former. We concluded that about 50.0% of the horse grooms lacked serologic evidence of exposure to WNV and were therefore susceptible in the event of a WNV outbreak. Continual surveillance for WNV among horse grooms and other occupationally exposed individuals in southwest Nigeria is recommended for prompt detection of new infections.

Key words: WNV infection, Seropositivity, Horse grooms, Nigeria