Abstract:
Q fever in animals and humans and its economic and public health significance
has been widely reported worldwide but in South Africa. There are few studies
on the prevalence of this zoonosis and its associated risk factors in South African
livestock. Therefore, a cross-sectional study was conducted to determine the
seroprevalence, molecular prevalence, and risk factors associated with C. burnetii
in cattle on farms in South Africa’s Limpopo province. Out of 383 cattle tested for
antibodies, the overall seroprevalence was 24.28%. Herd size of >150 (OR: 9.88;
95%CI: 3.92–24.89; p < 0.01) remained associated with C. burnetii seropositivity
in cattle. For PCR detection, targeting IS1111 fragment, cattle with no abortion
history (OR: 0.37; 95%CI: 0.18–0.77; p < 0.01) and herd size of >150 (OR: 3.52;
95%CI: 1.34–9.24; p < 0.01) remained associated with C. burnetii positivity. The
molecular prevalence in sheath scrapings and vaginal swabs by IS1111 PCR was
15.67%. Cohen’s kappa agreement test revealed a fair agreement between the PCR
and ELISA results (k = 0.40). Sequence analysis revealed that the amplicons had
similarities to the C. burnetii transposase gene fragment, confirming the presence
of the pathogen. The higher seroprevalence than molecular prevalence indicated
a past C. burnetii infection, no bacterial shedding through vaginal mucus in cows,
or preputial discharge in bulls. Similarly, the detection of C. burnetii by PCR in the
absence of antibodies could be partly explained by recent infections in which
antibodies have not yet been produced against the bacteria, or the level of these
antibodies was below the detectability threshold. The presence of the pathogen
in cattle and the evidence of exposure, as shown by both PCR and ELISA suggests
an active circulation of the pathogen. This study demonstrated that C. burnetii
is widespread in the study area and that a herd size of >150 is associated with C.
burnetii seroprevalence and molecular prevalence.
