Epidemiological insights into bovine babesiosis in South African cattle

Bovine babesiosis, caused by Babesia bovis and Babesia bigemina, is a major cattle disease in South Africa. This study combined prospective (2022-2023) and archived (2016-2022) DNA samples to assess molecular prevalence and serological exposure to Babesia spp. across thirteen dip tanks in the Mnisi area (Mpumalanga), plus five additional high-risk areas: Manaleni and Boekenhouthoek (Mpumalanga), Phuthaditjaba and Harrismith (Free State), Bergville (KZN). TaqMan quantitative PCR (qPCR) and indirect fluorescent antibody testing (IFAT) were used to assess current parasitaemia and prior exposure. In Mnisi, 81/216 cattle tested positive for at least one Babesia spp. (38%, 95% CI: 0.31-0.44), comprising 41 single B. bovis infections (19%, 95% CI: 0.14-0.25), 12 single B. bigemina infections (6%, 95% CI: 0.03-0.09), and 28 mixed infections (13%, 95% CI: 0.09-0.18), while 135 animals were negative (63%, 95% CI: 0.56-0.69). In the remaining areas, 113/187 cattle were positive (60%, 95% CI: 0.53-0.67). The overall prevalence of B. bigemina was highest in the Free State (51%), while B. bovis was predominant in KZN (62%), with Mpumalanga showing a higher relative occurrence of B. bovis (32%) than B. bigemina (22%). Agreement analysis from Mnisi subset (n = 101, 2022) with paired IFAT and qPCR results revealed slight agreement for B. bovis (K = 0.12, 95% CI: -0.05-0.29), with McNemar's exact test confirming systematic rather than random discordance (χ2 = 12.26, p = 0.00046). This supports the complementary application of both assays, as qPCR and IFAT reflect active parasitaemia and historical exposure, respectively, informing enzootic stability monitoring and control strategies.