Herd and animal level seroprevalence and associated risk factors of Leptospira interrogans sensu lato serovar Hardjo in cattle in southwest Ethiopia

Leptospirosis is a significant zoonotic disease that causes high economic losses in cattle production due to its association with abortions, stillbirths, infertility, and reduced milk yields. However, the epidemiology of bovine leptospirosis in Ethiopia is poorly understood. From October 2020 to October 2021, a cross-sectional study was conducted to investigate the seroprevalence of serovar Hardjo in cattle in southwest Ethiopia, as well as the associated risk factors. To test for the existence of L. Hardjo antibodies, blood samples were taken from 461 cattle. Indirect ELISA was used to identify the presence of antibodies against L. Hardjo in sera samples. We conducted a multivariable random-effect logistic regression analysis to identify potential risk factors associated with L. Hardjo seropositivity. An overall L. Hardjo seroprevalence of 24.7% (95% CI: 20.2-48.8) and 53.5% (95% CI: 45.7-90.5) was recorded at the animal level and the herd level, respectively, in the study areas. This study revealed six factors influencing L. Hardjo seropositivity in cattle herds. Large herds had twice the odds of seropositivity (OR = 2.0, 95% CI: 1.1-3.8) compared to small herds. Co-grazing cattle exhibited higher odds (OR = 2.2, 95% CI: 1.2-4.1) of seropositivity. Extensive management systems significantly increased the odds (OR = 10.3, 95% CI: 1.7-61.8) compared to semi-intensive systems. Highland cattle had higher odds (OR = 3.7, 95% CI: 1.4-10.3) than lowland cattle. Older cattle (OR = 4.6, 95% CI: 2.4-8.9) were more likely to be seropositive. At the herd level, extensive management (OR = 2.8, 95% CI: 1.3-5.8) and large herds (OR = 2.5, 95% CI: 1.3-4.7) increased the risk of seropositivity. Herds with sheep/goats (OR = 2.3, 95% CI: 1.3-4.1) were also at higher risk, highlighting significant L. Hardjo seropositivity risk factors in cattle herds. The study findings showed that leptospirosis was highly prevalent across the study areas. As a result, use proper management, raise zoonotic awareness for leptospirosis, and conduct molecular bovine leptospirosis research in study areas were recommended.