Rescued turtles turn up new parasite
A wild turtle, left tethered to a stake through a hole stabbed into her neck, is one of five rescued western long-necked turtles (Chelodina colliei) subsequently found to host an entirely new species of Eimeria parasite.
When Kanyana Wildlife Rehabilitation Centre’s Belinda Brice discovered evidence of Eimeria-like parasites in faecal samples collected from the rescued turtles, she sent the samples to Murdoch University’s Dr Rongchang Yang.
« We tested samples from all 25 turtles for the presence of spore-like oocysts, which are very characteristic of Eimeria parasites, » Dr Yang says.
« We found that five turtles, including the injured turtle, were shedding Eimeria. »
Dr Yang followed up Ms Brice’s initial microscopic observations with modern molecular techniques, combining the two in an attempt to identify the parasite.
« We were able to use a micromanipulator to select morphologically identical oocysts, one by one, then we extracted their DNA, » he says.
Dr Yang then used polymerase chain reaction, or PCR, to target three genetic sites on the oocyst’s DNA, attempting to detect tell-tale gene fragments that could help place the Eimeria species relative to its genetic family.
« Analysis revealed that the Eimeria detected is a new species, and is genetically distinct from other identified Eimeria species, » Dr Yang says.
After undergoing several surgeries—and testing negative for the parasite—the injured turtle was rehabilitated back into the wild, along with three of the other five Eimeria-positive turtles.
None of the turtles displayed clinical signs of coccidiosis—disease caused by parasites including Eimeria.
A first for Australian turtles
The parasite species, named Eimeria collieie, is the first in more than 1700 described Eimeria species worldwide to be characterised from Australian turtles.
« There is a lack of basic knowledge on the biodiversity and pathogenesis of coccidian parasites in native reptile, marsupial and bird populations, » Dr Yang says.
« We are working to establish this baseline data to better understand the disease risks to reptiles, marsupials and birds, as well as humans. »
The ongoing project is being led by Murdoch parasitology expert Professor Una Ryan.
The western long-necked turtle is found in metropolitan Perth and across the south-west.
It shares its range with the critically endangered western swamp tortoise (Pseudemydura umbrina).