Patterns in the Presence of Respiratory Tract Mycoplasmas in Four Species of North American Tortoises

Abstract

There are two known pathogens Mycoplasma agassizii and M. testudineum that cause upper respiratory tract disease (URTD) in some species of tortoises. Here, we sought to determine the presence and frequency of these bacteria among four North American tortoise species: Gopherus polyphemus (gopher tortoise), G. berlandieri (Texas tortoise), G. morafkai (Sonoran desert tortoise), and G. agassizii (Mojave desert tortoise) in populations that were sampled in three replicate sites. We assessed the presence of mycoplasmas using quantitative polymerase chain reactions (qPCR) on DNA extractions from nasal flushes. The qPCR process showed that both Mycoplasma pathogens were present in the four species of tortoises. Statistical analyses indicated that “species” and “sample site” were significantly associated with the presence of M. agassizii, while only site was significant for the presence of M. testudineum. The Mojave desert tortoise populations had the greatest frequency (70%) of M. agassizii, and Texas tortoise populations had the greatest percentage (31%) of M. testudineum. Variation among sites for M. agassizii was extreme (0% - 88%), but variance was not as prominent for M. testudineum (0% - 53%). Additionally, the presence of mycoplasmas in the nasal cavity was not a significant predictor for clinical signs of URTD. We conclude that collecting samples from more sites could have led to different conclusions, and including additional sites would allow for a better picture of current pathogen-tortoise interactions. We also recommend including climate data and population density in future analyses. Additionally, we suggest rerecording clinical signs of URTD of the tortoises after eight weeks from the initial nasal lavage and recording because appearance of clinical signs of the disease may not show for eight weeks in tortoises (Guthrie et al., 2013).