Seroprevalence and potential risk factors of Leptospira interrogans serovar Hardjo infection in dairy cattle of Tanahun district, Nepal

Context Leptospirosis is a zoonotic disease, with significant economic and public health implications. Although the government of Nepal has enlisted leptospirosis as a prioritized zoonotic disease, limited studies and control policies have been designed to estimate its prevalence at the human–animal interface. Hence, the burden of Leptospira infection in the cattle population of Nepal is poorly understood. Aims A cross-sectional study was conducted from August 2022 to December 2022, to estimate the seroprevalence and identify potential risk factors for Leptospira interrogans serovar Hardjo infection in cattle of the Tanahun district, Nepal. Methods In total, 407 blood samples were collected from 216 dairy cattle herds ranging in size from 1 to 140 animals and covering all 10 municipalities of Tanahun. Extracted serum was examined using an indirect antibody ELISA test. Concurrently, a questionnaire survey was conducted among 216 farmers to understand their husbandry practices, along with their knowledge of zoonoses. Univariable followed by multivariable logistic regression was performed to determine the association of potential risk factors, with the presence of Leptospira infection. Key results Results showed that the herd-level and animal-level seroprevalence of Leptospira exposure was 6.48% (n = 14/216, 95% confidence interval (CI): 3.59–10.64) and 4.91% (n = 20/407, 95% CI: 3.20–7.47) respectively. In the final multivariable model, four herd-level factors, namely, buying and selling of animals within the district (P = 0.046, OR: 0.14, 95% CI: 0.02–0.97), working nature of farmers, i.e. both in field and in cow shed (P = 0.028, OR: 3.66, 95% CI: 1.15–11.61), presence of rodents (P = 0.037, OR: 26.92, 95% CI: 1.22–593.87), and a herd size of greater than three (P = 0.031, OR: 8.52, 95% CI: 1.21–59.89), were associated with seropositivity to Leptospira organism. Similarly, two animal-level factors, i.e. cattle origin (P = 0.018, OR: 2.76, 95% CI: 1.19–6.38) and tick infestations (P = 0.035, OR: 0.30, 95% CI: 0.10–0.92), were associated with Leptospira exposure. It was found that 58.3% (126/216) of the respondents were aware of zoonosis, whereas only 5.6% (12/216) of the farmers knew about leptospirosis as a zoonotic disease. Conclusion On the basis of these research findings, the farmers and general public should be made aware of this zoonosis and the key precautionary measures to be adopted. Implication A comprehensive study to estimate the national-level prevalence of Leptospira spp. is required for the development of control strategies following one health approach.