Prevalence and factors associated with Babesia bigemina infection in Crioula Lageana cattle breed.

The objective of this study was to determine the prevalence of Babesia bigemina infection and associated risk factors in Crioula Lageana cattle, a Brazilian native breed known for its tick resistance. Blood samples were collected from 311 registered cattle (62 males, 249 females) from conservation nucleus properties in Santa Catarina State, Brazil. Samples underwent DNA extraction and nested PCR targeting the rap-1a gene for B. bigemina detection. Animals were categorized by sex, age class, and tick presence during sampling. An epidemiological questionnaire assessed potential risk factors. The overall B. bigemina prevalence was 60% (186/311; 95% CI: 56,95%-62,67%). Males showed significantly higher infection rates (79%; 49/62) compared to females (55%; 137/249; OR=3.36, p<0.001). Bulls (81%; 26/32) and calves (78%; 56/72) exhibited higher infection rates than cows (50%; 70/141) and heifers (52%; 34/66; p<0.001). Tick presence during sampling increased infection probability (OR=2.00, p=0.006). Contact with other animal species (OR=1.57, p=0.037) and regular veterinary care (OR=6.77, p=0.009) were identified as significant risk factors. Results indicate enzootic instability in the studied population, with distinct sex-based susceptibility patterns. These findings provide baseline data for developing targeted control strategies for B. bigemina in Crioula Lageana breeding programs.