Contribution of herd management, biosecurity, and environmental factors to the risk of bovine tuberculosis in a historically low prevalence region

•Eradication of bovine tuberculosis in low-prevalence areas remains a challenge.•The effect of farm and environmental factors on disease risk in dairy was evaluated.•The prevalence index measured the risk of disease occurrence over a 5-year period.•Badgers, sheep, and movement to pastures on foot were linked to a higher index.•On-farm risk characterisation is key to disease clearance. Eradication of bovine tuberculosis (bTB) in certain historically low-prevalence regions remains elusive. A complete characterisation of the husbandry practices, biosecurity, and environment where farms are located is crucial to implement targeted in-farm risk mitigation protocols. Here, a detailed survey performed in 94 dairy cattle farms located in Navarra, a low-prevalence region of Spain between 2016 and 2020 was carried out. Data on 73 biosecurity, farm-, and environmental-level factors potentially associated with the risk of bTB occurrence were evaluated using an ordinal logistic regression model: farms were classified based on their prevalence index, a score linked to each farm to account for the severity and recurrence of bTB cases: 22.3% of the farms had a score of 1, 21.3% a score of 2, 26.6% a score of ≥ 3, and 29.8% were negative herds. A statistically significant association between a higher prevalence index and the frequency of badger sightings along with the lease of pastures to sheep during Winter was identified. Farms that detected badgers on a monthly to daily basis in the surroundings and those that leased pastures for sheep flocks during Winter were four [odds ratio, 95% CI (4.3; 1.1–17.5)] and three (3.1; 1.0–9.9) times more likely to have the highest prevalence index, respectively (predicted probabilityprevalence index≥3 = 0.7; 95% CI 0.3–0.9). Conversely, farms that used a vehicle to transport animals from holdings to pastures were less likely (0.1;