Epidemiology of Bancroftian Filariasis in Relation to Urbanisation Gradient in Ibadan, Oyo State

The epidemiology of bancroftian filariasis in rapidly urbanising cities is incompletely understood, as urban development alters Culex mosquito habitat availability and vector-human contact patterns in ways that may sustain or attenuate transmission. This study investigated the epidemiology of Wuchereria bancrofti infection across an urbanisation gradient in Ibadan, Oyo State, Southwest Nigeria. A cross-sectional seroepidemiological survey was conducted in 400 adults from urban, peri-urban, and rural zones of Ibadan. Circulating filarial antigen was detected using the filariasis test strip. Mosquito abundance and species composition were assessed in each zone using light traps. Environmental variables including open drain density, sanitation access, and green space were geo-referenced. Circulating filarial antigen prevalence declined significantly with increasing urbanisation: 8.7 percent in rural, 5.1 percent in peri-urban, and 1.4 percent in urban zones. Open drain density was positively correlated with Culex quinquefasciatus abundance, which in turn predicted antigen prevalence. Two of three urban antigen-positive cases resided in slum micro-environments within the urban zone. Mass drug administration coverage also varied inversely with urbanisation. These findings demonstrate persistent filariasis transmission in informal urban settlements and call for targeted supplementary intervention in slum communities of Ibadan, independent of formal mass drug administration coverage metrics. Keywords: bancroftian filariasis, urbanisation, Wuchereria bancrofti, Culex quinquefasciatus, Ibadan.