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.
