Summary: | Background & objective: Urban malaria is on the rise in Nigeria due to rapid industrialisation anddevelopmental activities. A study was undertaken in Lagos, Nigeria to study the Anopheles breedingin polluted water bodies.Methods: Anopheles larval breeding habitats were surveyed and water samples from 24 larval breedingsites from four strategic areas in urban Lagos were analysed. The relationship between eight abioticvariables (pH, dissolved oxygen, conductivity, hardness, nitrate, total dissolved solids, turbidity andoil) and density of Anopheles larvae were investigated. The levels of heavy metals (Zn, Co, Cu, Pb,Mn, Fe, Hg and Ni) pollution were analysed by Atomic Absorption Spectrophotometry.Results: Morphological and PCR analysis of 2358 anopheline larvae revealed only the presence oftwo members of the Anopheles gambiae complex consisting of 93.1% Anopheles gambiae s.s. and6.9% An. arabiensis. Multiple regression analysis revealed a significant association betweenoccurrence of An. arabiensis larvae and two independent variables: pH and turbidity but not for An.gambiae s.s. The levels of three heavy metals: Fe, Cu and Pb from more than half of the sites surveyedwere three times higher than the values obtained in natural breeding sites of An. gambiae s.s. from arural area of Lagos. Over 85% of An. gambiae s.s. larvae were found in water bodies characterisedby low dissolved oxygen (<3 mg/L), high conductivity (>900 uS/cm), turbidity (>180 FAU), oil(>11 mg/L) and heavy metals: Fe, Cu, and Pb (>0.4 mg/L).Interpretation & conclusion: These results indicate that An. gambiae s.s. is adapting to a wide rangeof water pollution in this urban area. The survival of the mosquito in widespread polluted waterbodies across Lagos metropolis could be responsible for the rise in the incidence of malaria.
|