Seroprevalence of brucellosis in humans and livestock in Sub-Saharan Africa: a systematic review and meta-analysis.

Abstract

<h4>Background</h4>Brucellosis is a neglected tropical zoonotic disease of public health and economic concern. The disease is maintained within the populations by infected animals, and humans get infected via the consumption of livestock products and contact with post-parturient materials from an infected animal. Understanding the extent and distribution of the disease in both humans and animals is necessary for effective prevention and control in Sub-Saharan Africa (SSA). Therefore, this systematic review and meta-analysis aimed to determine the seroprevalence of brucellosis in humans and domestic livestock in SSA.<h4>Methods</h4>The review protocol was registered with the International Platform of Registered Systematic Review and Meta-analysis Protocols (INPLASY) under registration number: INPLASY2023120123. A comprehensive search was done in six databases: PubMed, OpenAlex, Google Scholar, Semantic Scholar, and Cross-ref, utilizing Medical Subject Headings (MESH). A number of keywords relevant to the subject of study were used to search through the selected online databases for articles published between 01 January 2012 and December 2024. Two hundred forty two full-text articles that fulfilled the eligibility criteria, distributed across 25 countries in SSA, were included in the final analysis. Cross-sectional studies that reported seroprevalence estimates on brucellosis infection for humans and domestic livestock species were included, whereas studies that reported seroprevalence estimates involving wildlife species and outside sub-Saharan Africa were excluded. The random effects meta-analysis model was used to pool the extracted seroprevalence data using R version v4.4.2. Subgroup analysis was performed for species, SSA region, country, diagnostic test, risk of bias, and whether the study was probabilistic or not. Heterogeneity between the studies was represented using I² and tau² statistics. A meta-regression model was used to investigate potential sources of heterogeneity. Publication bias was assessed using funnel plots, Peters' and Egger's tests, and corrected statistically using trim and fill analysis.<h4>Results</h4>The overall pooled seroprevalence of brucellosis was found to be approximately 5.7% (95% CI 5.01-6.47, tau² = 1.5303, I² = 97.6%). The pooled prevalence in humans was 10.15% (95% CI 7.61-13.41), which was higher than all other livestock species except donkeys. Subgroup analysis revealed that the seroprevalence of brucellosis significantly varied extensively between studies among the different species, across SSA countries and regions (East Africa, West Africa, South Africa, and Central Africa), and diagnostic tests. The year of study, species type, and diagnostic test significantly influenced the heterogeneity between studies. There was publication bias according to Egger's regression test (bias estimate = - 5.8518, p < 0.0001). Trim and fill analysis revealed a seroprevalence estimate of 14.14% (95%CI 12.21-16.31) that significantly differed from the observed pooled seroprevalence.<h4>Conclusion</h4>We report high seroprevalence of brucellosis in SSA in both humans and animals based on the current results of the pooled seroprevalence from the studies. The burden is higher in humans compared to domestic livestock; however, this may be underestimated due to fewer studies and challenges with limited diagnostic capacity in most healthcare settings in SSA. The majority of the studies reported in this review utilized mainly RBT and ELISA compared to other sero-diagnostic tests available. Overall, we recommend strengthening biosecurity measures to reduce the burden of brucellosis in humans in all SSA countries as well as improving public awareness of the zoonotic nature of brucellosis to effectively prevent and control brucellosis in both livestock and humans.<h4>Systematic review registration</h4>INPLASY2023120123.