Prevalence of Haemogregarine Parasites in Three Freshwater Turtle Species in a Population in Northeast Georgia, USA

摘要

Intracellular Haemogregarine parasites (Order Eucoccidiorida, suborder Adeleorina) are often found in freshwater turtles, appearing as banana-shaped structures in the cytoplasm of host erythrocytes. They are thought to be transmitted by leeches, although it is not clear if turtles with high leech parasitism also have high prevalence of Haemogregarine infections. We investigated this idea in freshwater turtles from a pond population in Northeastern Georgia, USA. Turtles were captured with baited hoop traps and blood samples obtained to make blood smears. A total of 23 turtles were captured representing 3 species - 2 that are aerial basking ( Trachemys scripta and Chrysemys picta ) and one bottom-dwelling species ( Sternotherus odoratus ). The incidence and severity of Haemogregarine infections was recorded from the blood smears. Multiple stages of intraerythrocytic gametocytes were observed, but the exact identity of the parasite was unknown. Initial evidence from DNA extraction and gene sequencing indicated the parasite was a member of the Hepatozoon clade of the suborder Adeleorina. Of all turtles, 52% of turtles were infected, which was within the range reported for other populations in North America (45-100%). The turtle species with the highest prevalence ( S. odoratus , 88.9%) was also the one known to harbor the most leeches. Moreover, female turtles were more likely to be infected than males (87.5 vs. 50.0%), which is also consistent with sex-related patterns of leech parasitism. Despite the generally high incidence of infection in this population, most infections were mild, as less than 1% of erythrocytes harbored Haemogregarines on average, which is a pattern found in other populations. Results from this study add to a growing body of literature on the nature of this host-parasite relationship.