Abstract
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.