Seroprevalence of Mycoplasma gallisepticum and Mycoplasma synoviae infection in the commercial layer flocks of the Centernorth of Iran

This survey was carried out to determine the seroprevalence of Mycoplasma gallisepticum (MG) and Mycoplasma synoviae (MS) infections in commercial layer farms in Centernorth of Iran. A total of 2000 serum samples were collected from 40 commercial layer flocks (50 samples/ flock) mostly > 40-week-old. Sera tested by serum plate agglutination (SPA) method using commercial MG antigen and MS antigen. Positive reactions retested by SPA on 1:8 dilution and the flocks with more than 10% positive reactions considered positive serologically. The results showed that 4 of 40 (10%) flocks were MG positive and the rest (90%) were negative. About MS, 17 of 40 (42.5%) flocks were positive and 33 of 40 (57.5%) were negative. Sera tested for MG were: 125 of 2000 (6.25%) positive, 1821 of 2000 (91.05%) negative and 54 of 2000 (2.7%) suspect. Sera for MS were: 371 of 2000 (18.55%) positive, 1617 of 2000 (80.85%) negative and 12 of 2000 (0.6%) suspect. Statistical analysis showed a positive correlation between MS positive flocks and strain (LSL flocks compared to Hy-Line flocks) and capacity of the farms significantly (P<0.05). It seems that the seroprevalence of MS in the commercial layer flocks of the Centernorth of Iran is high.   Key words: Mycoplasma gallisepticum, Mycoplasma synoviae, seroprevalence, serum plate agglutination test.