Bovine Brucellosis in Gauteng, South Africa: Seroprevalence amongst Cattle Handlers and Variables Associated with Seropositive Cattle Herds, 2014-2016

Krpasha Govindasamy; Peter N Thompson; Bernice N Harris; Jennifer Rossouw; Darrell A Abernethy; Eric M C Etter

doi:10.3390/pathogens10121547

Bovine Brucellosis in Gauteng, South Africa: Seroprevalence amongst Cattle Handlers and Variables Associated with Seropositive Cattle Herds, 2014-2016

Pathogens. 2021 Nov 26;10(12):1547. doi: 10.3390/pathogens10121547.

Authors

Krpasha Govindasamy¹, Peter N Thompson¹, Bernice N Harris², Jennifer Rossouw³, Darrell A Abernethy^{4

5}, Eric M C Etter^{1

6

7}

Affiliations

¹ Department of Production Animal Studies, Faculty of Veterinary Science, University of Pretoria, Onderstepoort 0110, South Africa.
² School of Health Systems and Public Health, University of Pretoria, Pretoria 0031, South Africa.
³ Centre for Emerging Zoonotic and Parasitic Diseases, National Institute for Communicable Diseases, Johannesburg 2192, South Africa.
⁴ Centre for Veterinary Wildlife Studies, Faculty of Veterinary Science, University of Pretoria, Onderstepoort 0110, South Africa.
⁵ Aberystwyth School of Veterinary Science, Institute of Biological, Environmental and Rural Sciences, Aberystwyth University, Penglais, Aberystwyth SY23 3FL, UK.
⁶ CIRAD, UMR AnimalS Health Territories Risks Ecosystems (ASTRE), 34070 Montpellier, France.
⁷ ASTRE, Univ Montpellier, CIRAD, INRA, 34070 Montpellier, France.

Abstract

In South Africa, the prevalence of cattle handler exposure to Brucella on cattle farms is unknown and risk factors and cattle symptoms associated with infected cattle herds are unavailable. To address this gap, a case-control study of cattle herds was conducted in Gauteng province and farm workers and veterinary officials were tested for exposure to Brucella. Seroprevalence amongst farm workers exposed to case herds ranged from 4.0% (BrucellaCapt^®) to 16.7% (IgG ELISA^®), compared to those exposed to control herds, where seroprevalence ranged from 1.9% (BrucellaCapt^®) to 5.7% (IgG ELISA^®). Seroprevalence amongst veterinary officials was significantly greater compared to farm workers exposed to case herds for the outcome RBT+ IgM- IgG+ (OR = 11.1, 95% CI: 2.5-49.9, p = 0.002) and RBT- IgM- IgG+ (OR = 6.3, 95% CI: 2.3-17.3, p < 0.001). Risk factors associated with being an infected herd were: being a government-sponsored farm vs. private farm (OR 4.0; 95% CI: 1.4-11.3; p = 0.009), beef vs. dairy herd (OR 7.9; 95% CI: 1.4-44.9; p = 0.020), open vs. closed herd (OR 3.3; 95% CI: 1.1-10.4; p = 0.038) and the presence of antelope on the farm (OR 29.4; 95% CI: 4.0-218.2; p = 0.001). Abortions (OR = 5.1; 95% CI: 2.0-13.3; p < 0.001), weak calves in the herd (OR = 8.0; 95% CI: 2.6-24.4; p < 0.001), reduction in number of calves born (OR = 9.0; 95% CI: 2.1-43.6; p < 0.001), reduction in conception rate (OR = 3.9; 95% CI: 0.8-18.3; p = 0.046), hygromas in cattle (p = 0.011) and farmers reporting brucellosis-like symptoms in their farm workers or in him/herself (OR = 3.4; 95% CI: 1.3-8.7; p = 0.006) were more likely to be associated with Brucella infected herds than control herds. This evidence can be used in strategic planning to protect both human and herd health.

Keywords: B. abortus; BrucellaCapt®; IgG ELISA®; IgM ELISA®; RBT®; South Africa; brucellosis; cattle handler; risk factor; seroprevalence; veterinary official.