Seroperivalence of Mycoplasma synoviae infectionin commercial layer farms of Alborz and Qazvinprovinces

This survey was carried out to determine the seroprevalence of Mycoplasma synoviae (MS) infection throughcommercial layer farms in Alborz and Qazvin provinces. A total of 2050 serum samples from 21 commercial layerflocks (50 samples from each farm), mostly over 40- week- old were collected during winter and spring seasonsrandomly. The sera were experimented for detecting the antibody against Ms by Serum Plate Agglutination (SPA)Test using commercial M. Synoviae antigen (Soleil Co., France). Positive reactions retested by SPA on 1/8 dilutionand the flocks with more than 10% of positive reactions were considered positive serologically.The results showed that in Alborz province: 10 out of 20 (50%) farms were positive and 10 out of 20 (50%) farmswere negative. Also, 170 out of 1000 (17%) serum samples were positive, 6 out of 1000 (0.6%) were suspect and824 out of 1000 (82.4%) were negative. In Qazvin province: 7 out of 21 flocks (33.3%) were positive and 14 out of21 flocks (66.7%) were negative. Also, 201 out of 1050 sera (19.14%) were positive, 6 sera (0.57%) were suspectand 843 sera (80.28%) were negative. Statistical analysis showed signifcant positive correlation between positiveflocks and strain (LSL strain serologically showed higher positive reaction rate compared to Hy-Line strain),capacity of flocks and the number of houses in the farms (P<0.05).It seems that the seroprevalence of Ms in layer flocks is high. However using MS live vaccine as interventionstrategy requires more detailed studies.