Mycoplasmal conjunctivitis in songbirds from New York

A held study was conducted to determine the prevalence of conjunctivitis an d Mycoplasma gallisepticum (MG) infections in house finches (Carpodacus mex icanus) and other song birds common to bird feeders in Tompkins County (New York, USA). Eight hundred two individuals of 23 species and nine families of birds were captured and given physical examinations during the 14 mo stu dy beginning in February 1998. Clinical conjunctivitis (eyelid or conjuncti val swelling, erythema, and discharge) was observed in 10% (19/196) of hous e finches examined, and only in the winter months from November to March. U nilateral conjunctivitis was observed in 79% (15/19) of affected house finc hes; one case developed bilateral disease between 8 and 18 days following i nitial examination. Conjunctivitis was observed in a similar proportion of males and females sampled, and body condition scores and wing chord lengths were not significantly different between diseased and non-diseased house f inches. Mycoplasma gallisepticum was isolated from 76% (13/17) of finches w ith conjunctivitis and 2% (3/168) of clinically normal house finches sample d during the study. DNA fingerprints of 11 MG isolates using random amplifi cation of polymorphic DNA (RAPD) techniques showed no apparent differences in banding patterns over the course of the study, suggesting persistence of a single MC strain in the study population. The prevalence of conjunctivit is and MG infections declined in house finches between February/ March 1998 and February/March 1999 (23% to 6%, and 20% to 5%, respectively), but only the former was significant (P < 0.05). Conjunctivitis was also observed in four American goldfinches (Carduelis tristis) and one purple finch (Carpod acus purpureus). Mycoplasma gallisepticum infection was confirmed in the pu rple finch, the first documented case of MG-associated conjunctivitis in th is species. The purple finch isolate was similar to house finch isolates fr om the study site by RAPD analysis. Positive plate agglutination (PA) tests were recorded in one other goldfinch and two purple inches, suggesting exp osure of these individuals to MG. Positive PA tests were also obtained from two brown-headed cowbirds (Molothrus ater) and four tufted titmice (Parus bicolor), but MG infection could not be confirmed in these cases due to lac k of samples. Based on these findings, the prevalence of MG infections in h osts other than house finches appear to be low in the population sampled. T here is growing evidence, however, that songbird species other than house f inches are susceptible to MG infection and disease.