Characterizing the Epidemiology of Historic and Novel Pathogens in Blanding’s Turtles (Emydoidea blandingii)
Pathogens such as herpesviruses, Mycoplasma spp., and frog virus 3-like Ranavirus have contributed to morbidity and mortality in many species of free-living and zoo-maintained chelonians; however, their prevalence is understudied in Blanding’s turtles (Emydoidea blandingii) across North America. To assess presence of these pathogens, Blanding’s turtles were sampled in Lake County, Illinois in 2017 (n=213) and 2018 (n=160). DNA from cloacal-oral swabs was assayed for four ranaviruses, three Mycoplasma spp., two Salmonella spp., Emydoidea herpesvirus 1 (EBHV1), and tortoise intranuclear coccidiosis using a multiplex quantitative polymerase chain reaction (qPCR). Pathogens were most frequently detected in adult turtles (n=25) and rarely in subadults (n=2) or juveniles (n=1). EBHV1 was detected in 22 individuals with few clinical signs of illness, most (n=20) occurring in the month of May (p<0.0001). EBHV1-positive turtles had lower relative lymphocyte counts and higher relative basophil counts and heterophil:lymphocyte ratios (p<0.05). EBHV1 cases at one study site significantly clustered within the same 0.64-km area from May 17 through May 22, 2017 (p<0.0001) and May 14 through May 15, 2018 (p=0.0006). Individuals were rarely positive for Salmonella enterica ser. Typhimurium (n=6). A novel Mycoplasma sp. sharing high homology with other emydid Mycoplasma spp. was detected in one turtle with nasal discharge using conventional PCR. Continued monitoring of this population and habitat may facilitate identification of risk factors for pathogen occurrence and clarify the impact of infectious diseases on Blanding’s turtle conservation outcomes.
The authors thank the Lake County Forest Preserve District for funding the project and assisting with sample collection.