Taking the strain out of onchocerciasis? A reanalysis of blindness and transmission data does not support the existence of a savannah blinding strain of onchocerciasis in West Africa

Onchocerciasis (also known as ‘river blindness’), is a neglected tropical disease (NTD) caused by the (Simulium-transmitted) filarial nematode Onchocerca volvulus. The occurrence of ‘blinding’ (savannah) and non-blinding (forest) parasite strains existence corresponding, locally adapted Onchocerca–Simulium complexes were postulated to explain greater blindness prevalence in savannah than forest foci. As result, World Health Organization (WHO) Control Programme West Africa (OCP) focused anti-vectorial anti-parasitic interventions endemic areas. In this paper, village-level data on prevalence, microfilarial transmission intensity (measured annual potential, number infective, L3, larvae per person year) extracted from 16 West–Central Africa-based publications, analysed according habitat (forest, forest–savannah mosaic, savannah) test dichotomous strain hypothesis relation blindness. When adjusting for sample size, there no statistically significant differences between habitats (one-way ANOVA, P = 0.68, mean 1.76 ± 0.37 (SE); mosaic 1.49 0.38; =1.89 0.26). well-known relationship potential was confirmed shown hold (but not be different from) foci (excluding southern Côte d’Ivoire, which significantly lower other African communities, but had been focus studies leading strain–blindness that accepted OCP planners). We conclude evidence blinding onchocerciasis simple contrast with equivocal. A re-appraisal patterns ocular needed improve understanding epidemiology burden estimates light WHO 2030 goals onchocerciasis.