Epidemiology of human Brucellosis in rural South Africa: Household survey of seroprevalence and risk factors, 2022–2023.

Introduction: Brucellosis, caused by Brucella spp., is a globally prevalent zoonotic disease and a significant cause of febrile illness, yet it often remains underdiagnosed. This study assessed brucellosis seroprevalence in a rural South African community and examined associated exposure factors among livestock-owning and non-livestock households.

Methods: A cross-sectional random cluster household survey was conducted in 2022–2023 in uMkhanyakude District, KwaZulu-Natal Province, South Africa. Household interviews were conducted, and serum samples from 688 participants were tested for anti‑Brucella IgG antibodies using a commercial ELISA. Risk factors for seropositivity were assessed using Fisher’s Exact test, with p<0.2 considered significant.

Results: Overall, human Brucella seroprevalence was 4.4% (30/688; 95% CI: 3.0–6.3%) after adjusting for household clustering. Participants had a median age of 36 years (IQR: 25–53; range: 12–95); 98% identified as Black African and 59% were female. Poultry ownership was common (74% kept chickens), while 12% kept cattle, 16% goats, and 39% both bovids. Univariable analysis showed higher seropositivity among males (7.9% vs. 2.0%; p<0.001), participants older than 36 years (6.3% vs. 2.4%; p=0.09), and those with primary-level or no schooling (6.9% vs. 3.0%; p=0.106). A strong association was observed with household cattle or goat ownership (6.4% vs. 0.4%; p<0.001), whereas associations with livestock slaughter (p=0.151) and abortions (p=0.19) were weaker. Behavioural factors associated with increased seropositivity included consumption of unboiled/raw milk (p=0.097) or fermented milk (p=0.077), eating animals found dead (p=0.059), and frequent hunting of antelopes, small mammals, or birds (p=0.085). No associations were found with the consumption of undercooked meat, employment status or sector, chicken ownership, or keeping cats/dogs as pets (stratified by bovid ownership). Multivariable analysis will be presented.

Conclusions: Brucellosis seroprevalence was associated with multiple demographic and behavioural factors, particularly sex, age and contact with cattle or goats. Strengthening livestock control measures, together with targeted awareness campaigns for high-risk groups, may reduce human Brucella exposure.