Pathogenesis of Isospora amphiboluri in Bearded Dragons (Pogona vitticeps)

SIMPLE SUMMARY: Coccidia are common parasites of captive animals. While there have been a number of studies evaluating the life cycles of these parasites in domestic pets and livestock, there has been limited research assessing the impact of these parasites on reptiles. Bearded dragons are a common pet lizard and are known to be infected by their own species of coccidia, Isospora amphiboluri. To determine the best practices for controlling this parasite in captive bearded dragons, it is important that we learn about what the parasite does once it infects the bearded dragon. This study found that Isospora amphiboluri infects the small and large intestines of bearded dragons. In addition, the time (pre-patent period) from exposure to shedding the parasite in feces is 15–22 days. This information is important for developing treatment and management protocols for captive bearded dragons to reduce their exposure to this parasite. ABSTRACT: Isospora amphiboluri is a common coccidian found in captive bearded dragons (Pogona vitticeps). To minimize the impact of this parasite, it is important to characterize its pathogenesis so that we can develop appropriate methods for diagnosis and treatment. Forty-five juvenile bearded dragons were used for this two-part study. In the first part, ten bearded dragons were infected with 20,000 oocysts per os, while a control group of five animals received only water. Feces were collected over 45 days and screened for oocysts. In the second part, thirty bearded dragons were used to characterize the pathogenesis of I. amphiboluri. Twenty-five bearded dragons were infected as described previously, while five animals served as controls. Five infected bearded dragons and one control were humanely euthanized on days 4, 8, 12, 16, and 20 post-infection for complete necropsies. The pre-patent period for I. amphiboluri was found to be 18.6 ± 1.9 days (range 15–22 days). Histopathology confirmed that I. amphiboluri follows a homoxenous life cycle. Infections begin in the duodenum and progress to the colon over time. The findings of this study can be used to develop better quarantine and treatment protocols for captive bearded dragons.