Risk Factors and Seroprevalence of Mycoplasma synoviae Infection in Broiler Beeder Farms

Background: Mycoplasmas are bacteria that belong to the class Mollicutes. Mycoplasmas are found in humans and animals, and the species that were recognized as pathogens of domestic poultry include Mycoplasma gallisepticum (MG) and Mycoplasma synoviae (MS) in chickens and turkeys, and Mycoplasma meleagridis and Mycoplasma iowae in turkeys. Mycoplasma synoviae (MS) infection occurs worldwide in commercial poultry flocks and may result in severe economic losses. Infection most frequently occurs as a subclinical upper respiratory infection, which can progress to respiratory disease with air sac lesions when exacerbated by other respiratory pathogens (e.g., Newcastle disease virus, Infectious bronchitis virus), or when more virulent MS strains are involved. Serological screening is routinely used as an indicator of MS infection. Control of MS is very dependent on serologic monitoring. Sera commonly are analyzed for antibodies using the serum plate agglutination (SPA) test, a hemagglutination-inhibition (HI) test and an enzyme-linked immunosorbent assay (ELISA) test. Some factors such as: age, size of flock, locale, etc., may effect on severity of MS in poultry flocks. This study was aimed to determine the risk factors (age, size of flock, locale and strain) and seroprevalence of M. synoviae in broiler breeder farms. Materials, Methods & Results: The study was conducted from May 2002 to October 2008 that was based on Rapid Serum Plate Agglutination (SPA) and Enzyme Linked Immunosorbent Assay (ELISA) tests. Three hundred and fifteen broiler breeder farms were followed for this study and three samples for every thousand were obtained randomly. Blood samples were aseptically collected from the wing veins using 5-mL sterile disposable syringes and needles. All serum samples were tested for MS by SPA, using a commercial antigen for the diagnosis of Mycoplasma synoviae by serum plate agglutination. Sera that were positive in SPA were analyzed for antibodies against MS using a commercially available ELISA antibody test kit. For statistical test SPSS (Chi square test and Pearson correlation) was used. The highest (41.2%) and lowest (0%) prevalence of MS infection was found in 2003 and 2008, respectively. The prevalence was highest (39.6%) in winter and lowest (30.6%) in summer. Ross, Cobb, Arian, Hubbard and Arbor Acres strains had 40%, 44%, 32%, 27% and 45% infection, respectively. The prevalence was recorded highest in above 60 weeks of age (43.1%), but at 10-20 weeks it was lowest (12.7%). No significant difference was seen in flocks up to 30,000 population (37.8%), 30,000-40,000 (46.8%) and upper 40,000 (51.3%). Farms were separated in two different zones ( foothills with less humidity compared with coastal area). The prevalence of Mycoplamosis in foothills was significantly (P < 0.05) higher (36.9%) than coastal area (30.1%). Discussion: Results showed that the prevalence of MS infection increased with the increase of age. No relation between a special breed with M. synoviae status could be found. Seasonal variation of prevalence with MS infection was observed in the present study. The population of the flocks was not influenced on Mycoplasma Synoviae prevalence. The results showed that occurrence of M. synoviae have a significant relationship with the age and zone of sampling.