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.

Mycoplasma (M.) hyopneumoniae is the key pathogen of the porcine respiratory disease complex (PRDC) and contributes to pleurisy in pigs. Due to its limited metabolism and laborious cultivation, molecular tools are useful for diagnosis. This study investigated the genetic diversity of M. hyopneumoniae in slaughter pigs with pneumonia and pleurisy, and it assessed co-infections by Pasteurella multocida type A (PM), Actinobacillus pleuropneumoniae (APP), and swine influenza virus A (sIVA). Lungs (n = 70) with different pleurisy scores and lesions compatible with M. hyopneumoniae infection were collected for convenience. Macroscopic and microscopic evaluations were performed. M. hyopneumoniae was detected using qPCR, and MLST was used for genetic characterization. Co-infections with PM and APP were also evaluated by qPCR, while the immunohistochemistry assessed sIVA infection. All lungs were positive for M. hyopneumoniae. Histopathology confirmed M. hyopneumoniae-associated lesions. MLST characterization was possible in 25 lungs and revealed 10 distinct allelic profiles, with none matching known sequence types in the public database. Co-infections were detected in 40% of the samples with APP and 32% with PM, with 12% showing both pathogens and 52% of the samples presenting microscopic lesions compatible with sIVA infection. The diverse genetic profiles found underscore the need for research on isolation and potential pathogenic variations.

Mycoplasma hyopneumoniae is the causative bacterium of porcine enzootic pneumonia and one of the primary etiologic agents of the porcine respiratory disease complex. Most Brazilian commercial pig farms are positive for this pathogen. However, the prevalence of the pathogen in backyard pig farms has not been described, to our knowledge. Therefore, we aimed to determine the prevalence of M. hyopneumoniae in backyard pig farms in the state of Paraná, Brazil. In January–March 2020, we collected 585 serum samples from pigs in 187 non-vaccinated herds. We tested the sera with an indirect ELISA for anti– M. hyopneumoniae antibodies and found that 182 of 585 (31.1%) samples were positive, and were found in 109 of 187 (58.3%) herds assessed.

The genus Salmonella , particularly Salmonella enterica subsp. enterica serovars Choleraesuis and Typhimurium, poses significant challenges to swine production and leads to economic losses from conditions such as septicemia and enterocolitis. We evaluated the effects of experimental infection with Salmonella Typhimurium on clinical signs and anatomopathologic outcomes in pigs. Twenty 90-d-old pigs were divided into 2 groups: G1 received an oral inoculum of 10 ⁸ cfu of Salmonella Typhimurium; G2 served as a control. Pigs were monitored clinically for 30 d; postmortem examinations and microbiologic analyses were conducted. No significant differences were found in rectal temperature or weight between groups; however, diarrhea episodes were noted in the challenged group starting on day 5 post-inoculation. Isolates of Salmonella Typhimurium were detected intermittently in the challenged group; all positive samples came from pigs without diarrhea. Macroscopic lesions in G1 pigs included button-shaped ulcers in the ileocecal region, enlarged or hemorrhagic mesenteric lymph nodes, and hyperplasia of lymphoid tissue in the colon.