Molecular and Serological Detection of <i>Coxiella burnetii</i> in Small Ruminants in Northeastern Brazil

Coxiella burnetii, the causative agent of Q fever in humans, is an important worldwide pathogen. The main reservoirs for the bacterium are ruminants, specifically sheep and goats, which act as major shedders of the bacterium in the environment. In addition, the bacterium causes significant economic losses on small ruminant farms due to abortion and other reproductive disorders, such as weak neonates or stillborn animals. Transmission between animals and humans can occur mainly through the inhalation of aerosols, direct contact with products of labour or fomites, or through the vectorial route (ticks), which is less common. To evaluate the presence of C. burnetii antibodies in small ruminants, 76 serum samples, with 34 from sheep and 42 from goats were collected and analysed by ELISA. Furthermore, to explore the dynamics of C. burnetii excretion routes in sheep and goat flocks, vaginal, milk, and fecal samples were collected from 92 animals with 60 from goats and 32 from sheep. We also explored environmental contamination in the animals' pens. The seroprevalence was 31.5% (24/76). The highest frequencies found in qPCR were in vaginal swabs (30.4%-28/92), followed by milk (26%-24/92), and lastly, in faeces (8.6%-8/92). None of the environmental samples were positive in qPCR. The data indicates that C. burnetii is actively circulating among sheep and goats in the region. The bacterium is disseminated through multiple transmission routes, affecting flock health and posing a significant occupational risk to farm workers involved in sheep and goat operations. SUMMARY: Serology indicates that one-third of the sheep and goats had previously been infected with Coxiella burnetii. qPCR analysis revealed the ongoing presence of C. burnetii in all evaluated flocks, each with a previous history of reproductive disorders. These results indicate the need for preventive measures and control of C. burnetii infection in small ruminants.