Current epidemiology of histoplasmosis in Nigeria: A systematic review and meta-analysis

Introduction: Histoplasmosis commonly occurs in the advanced HIV disease population and also in immunocompetent individuals. Previous reviews and recent studies highlight several cases of histoplasmosis reported in Nigeria. We aimed to describe the current epidemiology of histoplasmosis in Nigeria and the need for active surveillance in the at-risk populations. Methods: Literature searches for all publications on histoplasmosis in Nigeria were performed using online databases including Google scholar, PubMed and African Journal online. The following search terms: 'histoplasmosis' and 'Nigeria', AND/OR 'Histoplasma and Nigeria' were used. No limitations on the date or other search criteria were applied, to avoid the exclusion of articles on histoplasmosis in Nigeria. All publications on histoplasmosis outside Nigeria were excluded. Results: Our review identified a total of 231 cases of histoplasmosis reported from Nigeria: 128 were from individual case reports and case series while 103 were cases from two observational studies. Of the 231 cases, 97 (42.0%) were from South West Nigeria, 66 (28.6%) were from South-South Nigeria, 24 (10.4%) were from North West, 22 (9.5%) from North Central Nigeria, 17 (7.4%) from South East Nigeria and 5 (2.2%) from the North East. Based on Nigeria's current population size of 216,953,585 the burden of histoplasmosis per 100,000 inhabitants was estimated to be 0.1%. The sheer number of cases detected in recent observational studies compared with individual case reports and series reported over a longer duration of 6 decades suggests gross under-reporting of histoplasmosis in Nigeria. Conclusion: Histoplasmosis is not an uncommon clinical entity in Nigeria. Histoplasmosis case finding should be improved by training and retraining healthcare professionals and providing much-needed diagnostic capacity and infrastructure across health facilities in Nigeria.