Test helps detect Cryptosporidium species in pet reptiles
MedWire News: Researchers have developed a test to aid the diagnosis of cryptosporidiosis in pet snakes and lizards.
Cryptosporidiosis is a well-known gastrointestinal disease in these animals, but its diagnosis is complicated by the fact that the presence of cryptosporidia in the animal feces does not necessarily mean the animal is infected.
Because snakes and lizards digest cryptosporidia parasites from their prey, not all species found in their feces cause infection.
Barbara Richter and colleagues from the University of Veterinary Medicine in Vienna, Austria, have now devised a test that uses polymerase chain reaction (PCR) assay to detect cryptosporidian species that cause infection.
The PCR assay targets a part of the 18S ribosomal RNA gene, and the researchers used a consecutive sequencing reaction to identify the cryptosporidian species present in PCR-positive samples.
Using the test, they identified two species Cryptosporidium serpentis and Cryptosporidium varanii (saurophilum), both of which have been previously associated with gastrointestinal tract disease in snakes and lizards.
C. varanii (saurophilum) had a relatively high prevalence in corn snakes and leopard geckos, detected in a respective 17 (16%) out of 106 samples and 32 (7%) out of 462 samples. This compared with a prevalence of just 2 (3%) out of 68 samples from other snakes.
C. varanii is generally considered to be present mainly in lizards, so the high susceptibility of corn snakes to this species was unexpected, the researchers note.
The detection of C. serpentis in eight (2%) out of 462 samples from leopard geckos, but not in snake samples, was also unexpected. Overall, cryptosporidian species with known pathogenecity for reptiles were present in 40 (9%) out of 462 leopard gecko samples.
The findings show the widespread nature of cryptosporidiosis, although it is possible that some of the infections do not inconvenience the host reptile. However, these infections still make the animals a source of infection for other reptiles. There is also a significant risk for cross-species infection given that many reptile collections house a number of species together, the researchers note.
They conclude in the Journal of Veterinary Diagnostic Investigation that "the described combination of PCR assay and sequencing reaction proved to be useful in the diagnostics of cryptosporidiosis in live reptiles."
However, the team cautions that cryptosporidia are often present in very low numbers in the feces of reptiles and so could easily be missed in a single test.
"We are working to make our method more sensitive but it is very important to test the reptiles repeatedly. A negative result does not necessarily mean that the animal is really free of the parasite," Richter commented.
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By Lucy Piper