Prevalence and Risk Factors of Leptospira spp. Infection in Backyard Pigs in the State of Paraná, Brazil

SIMPLE SUMMARY: Leptospirosis is a zoonotic disease that has been increasingly reported around the world. A variety of domestic and wild animal species can serve as natural or accidental hosts for the pathogenic Leptospira spp. Among these, swine can function as either maintenance or accidental hosts. This study aimed to investigate the prevalence of Leptospira spp. infection and associated risk factors in backyard pigs in the state of Paraná, Brazil. Serological analysis was performed on 1393 serum samples collected from pigs on 188 subsistence properties in different regions of the state. The samples were tested using the microscopic agglutination test (MAT) to detect antibodies against 24 different Leptospira spp serovar. The results showed an overall seroprevalence of 68.78% for Leptospira spp. antibodies, with the most commonly detected serogroups being Icterohaemorrhagie (19.58%), Pyrogenes (7.94%), and Pomona (7.94%). The lack of rodent control has been identified as a risk factor for Leptospira spp. infection in the backyard pig population. This study highlights the high prevalence of Leptospira spp. infection in backyard pigs’ sites in Paraná and emphasizes the importance of implementing measures to control and prevent the spread of this zoonotic disease. ABSTRACT: Leptospirosis is a zoonotic disease that poses a significant threat to human and animal health worldwide. Among different animal species, pigs are known to play a crucial role in the transmission of the pathogenic Leptospira spp. This study aimed to investigate the prevalence of Leptospira spp. infection and associated risk factors in backyard pigs in the state of Paraná, Brazil. A set of 1393 blood samples were collected from pigs on 188 subsistence properties from 136 different municipalities of the Paraná state and tested using the microscopic agglutination test (MAT) to detect antibodies against 24 different Leptospira spp. serovars. The results revealed an overall seroprevalence of 15.87% (221/1393; 95% CI: 13.95–17.78%) for Leptospira spp. antibodies, with Icterohaemorrhagiae, Butembo, and Pomona being the most commonly detected in serovar levels. The lack of rodent control (OR 1.12, 95% CI: 0.63–1.98, p = 0.02) was the only variable associated with disease incidence and was identified as a significant risk factor for Leptospira spp. infection in this context. These findings highlight the urgent need to implement effective control measures, such as improved housing conditions, rodent control, and veterinary assistance, to prevent the spread of this zoonotic disease in backyard pigs in Paraná, Brazil.