Occurrence and relevance of mycoplasma sturni in free-ranging corvids in germany

Several Mycoplasma spp. are well-known pathogens in poultry. In birds of prey, White Storks (Ciconia ciconia), and some waterfowl (Anatidae, Pelecanidae) species, mycoplasmas occur commonly and seem to be apathogenic or commensal and most likely belong to the physiologic microbial flora of the respiratory tract. In other bird species, such as Common Nightingales (Luscinia megarhynchos) and tits (Paridae), Mycoplasma spp. are absent in healthy birds. In corvids, the prevalence and role of Mycoplasma spp. in disease remains unclear. In previous studies, Mycoplasma sturni was detected in diseased corvids; however, those studies included only a limited sample size or preselected individuals. We collected tracheal swabs of 97 free-ranging Corvidae, including 68 randomly selected individuals from hunting bags and 29 birds that had been admitted to a veterinary clinic. Tracheal swabs were examined for Mycoplasma spp. using culture and genus-specific PCR. If Mycoplasma spp. were detected, the species were identified by sequencing the 16S ribosomal (r) RNA gene and 16–23S rRNA intergenic transcribed spacer region. Five of 68 (7%) of the hunted birds and nine of 29 (31%) of the birds admitted to the veterinary clinic were PCR positive. In 13 of 14 PCR-positive samples, mycoplasmas were cultured and M. sturni was the only mycoplasmal species identified. None of the positive corvids from the hunting bags had clinical signs, whereas five of nine birds admitted to the veterinary clinic showed apathy, lameness, injuries, or fractures, which may not be associated with mycoplasmal infections. These data support the notion that M. sturni is the Mycoplasma sp. most frequently found in corvids, though its prevalence and ability to cause disease may involve interaction with other aspects of bird health.