Objective: To determine the prevalence of Mycoplasma suis infection in swine, swine-farm workers, and swine veterinarians in Shanghai, China.
Sample population: 172 swine and 65 workers and veterinarians from 19 commercial swine farms.
Procedures: Blood samples were collected from all study subjects. Blood samples were examined for the presence of M suis by means of compound and scanning electron microscopy. A species-specific PCR assay was developed for detection of M suis DNA extracted from blood samples. Relationships between infection status of swine and sex, age, geographic location, and clinical signs of disease were evaluated by use of a C(2) test. The phylogenetic relationship between partial 16S ribosomal RNA (rRNA) sequences from swine and human isolates of M suis was determined.
Results: 86% (148/172) of swine and 49% (32/65) of humans had positive PCR assay results for M suis infection. Swine infection status was not associated with any variable, with the exception of pyrexia and subcutaneous bleeding. The partial 16S rRNA sequences from human and swine isolates of M suis were 98% homologous and in the same phylogenetic cluster as a previously identified swine isolate of M suis.
Conclusions and clinical relevance: A large proportion of swine and humans in close contact with those swine were infected with M suis in Shanghai, China. The close phylogenetic relationship between swine and human isolates of M suis suggested possible interspecies transmission; however, additional research is required to better assess that possibility.