EVALUATION OF DIAGNOSTIC PROCEDURES TO DETECT MYCOPLASMA-SYNOVIAE IN COMMERCIAL MULTIPLIER-BREEDER FARMS AND COMMERCIAL HATCHERIES IN FLORIDA

Sera from 5325 chickens representing 71 commercial poultry flocks were tested for Mycoplasma synoviae (MS) using standard National Poultry I mprovement Program (NPIP) resting guidelines. Based on the NPIP guidel ines, only sera (N = 195) from flocks that test positive by specific p late agglutination (SPA) were submitted for additional confirmatory te sts. Flocks from three multihouse farms were identified as seropositiv e for MS and confirmed by culture and polymerase chain reaction (PCR). Serum samples (N = 195) from these seropositive flocks were compared by SPA, enzyme-linked immunoassay (ELISA), and hemagglutination-inhibi tion (HI). Of the 195 sera tested for MS from these flocks, 145 (74%) sera were positive by SPA. Of the 145 SPA-positive sera, the HI rest w as positive for 127 samples (90.2%), whereas the ELISA was positive fo r 141 samples (98.6%). This difference between the two tests was signi ficant (P = 0.0006). Significant differences (P = 0.0002) in titer wer e obtained from paired serum samples that were submitted to three diff erent laboratories for HI analysis. Both the SPA and HI tests failed t o detect early infection in newly introduced flocks following depopula tion of MS-positive facilities. Both ELISA and PCR detected new infect ions on these farms. In the MS outbreak described in this study SPA wa s nor adequate as the sole screening test and HI was not adequate for confirmation of flock infection status. Continued reliance on the same or a similar type of testing could result in missed infections. Confi rmation of infection by PCR was preferable to HI and also may be used in place of culture. The findings of this study suggest that ELISA sho uld be considered as a serologic screen in lieu of SPA, screening with SPA may miss MS-infected flocks, and PCR should be considered as a co nfirmatory test.