Seroprevalence and Associated Risk Factors of Human Brucellosis in a Farming and Animal Health Community in South Africa, 2015–2016

Abstract

Brucellosis is a widespread zoonotic disease and a major contributor to febrile illness, often underdiagnosed. This study investigated the seroprevalence of brucellosis and the associated exposure factors within South African farming and animal health communities. A cross-sectional survey was conducted across 40,000 km2 in the Free State and Northern Cape provinces from 2015 to 2016. Interviews and serum samples were collected from 847 volunteers on randomly selected farms and veterinary professionals listed in a regional register. Samples were tested using a commercial Brucella IgG ELISA. Risk factors were assessed using logistic regression, accounting for within-farm clustering. The seroprevalence was higher among veterinary professionals (11.6%; 16/138) than farm-based participants (7.0%; 50/711); p = 0.095. Multivariable analysis identified several exposure factors within the farm-based population: age over 40 years (aOR = 5.35; 95% CI: 1.68–17.02), White population group (aOR = 4.60; 95% CI: 1.64–12.91), contact with diseased animals (aOR = 2.01; 95% CI: 1.05–3.84), and working 4–8 h daily with ungulates (aOR = 2.90; 95% CI: 1.25–6.76). Among veterinary professionals, odds of exposure were higher with more than 5 years of work (OR = 1.82; 95% CI: 1.21–2.72) and extended ungulate contact (OR = 4.85; 95% CI: 1.27–18.52). Occupational exposure highlights the need for improved brucellosis prevention strategies.