First detection of Coxiella burnetii subtype 61 in bulk tank milk from dairy farms in Brazil.

Coxiella burnetii (C. burnetii) is a Gram-negative bacterium that causes a cosmopolitan zoonosis called Q fever. C. burnetii infects a range of animals, but domestic ruminants (sheep, goats, and cattle) are the main reservoir for human infection. Coxiellosis is associated with reproductive disorders in animals, such as miscarriage, stillbirths, premature births, and infertility, posing a significant negative economic impact. We investigated the presence of C. burnetii in bulk tank milk samples from small family-operated farms in the Central West region of São Paulo, Brazil. Polymerase chain reaction (PCR), Nested PCR, and real-time PCR (qPCR- Sybr and Probe) followed by sequencing of products were performed. Additionally, we mapped the distribution of positive cases diagnosed in the different regions studied. C. burnetii was detected in 16/102 (15.68 %) by Nested-PCR, 22/102 (21.57 %) by qPCR/Sybr, and 32/102 (31.37 %) by qPCR/Probe. The agreement between methods was considered reasonable according to the Kappa analysis. C. burnetii was detected in seven of the eight cities investigated (87.50 %). All C. burnetii were ST61. Our findings indicate that C. burnetii is prevalent among family-operated dairy farms in this region of Brazil, underscoring the urgent need to develop comprehensive surveillance and control programs to mitigate the zoonotic risks associated with this bacterium.