Conjunctival Cryptosporidium avium infection in a captive inland bearded dragon (Pogona vitticeps)

Background: A rescued, captive, adult, male, inland bearded dragon (Pogona vitticeps) was presented with chronic swelling of the right upper and lower eyelids, with intermittent blepharospasm.
Case description: Histopathology revealed a proliferative conjunctivitis, including inflammation of the nictitating membrane, along with a mixed, chronic, inflammatory response. Located on the epithelial surface, were numerous, surface oriented apicomplexan organisms, histologically compatible with Cryptosporidium sp. Molecular characterisation revealed these organisms to be most closely related to C. avium based on amplification and sequencing of the 18S rRNA gene.
Conclusions and case relevance: This report describes the diagnosis of spontaneous conjunctivitis involving Cryptosporidium sp. in a reptile; C. avium has not been implicated previously in extra-enteric disease in a non-avian species. Infection by C. avium has only once been reported in lizards and this study provides further evidence that its host range may be broader than anticipated. Cryptosporidiosis should be considered as a differential diagnosis for refractory conjunctivitis in lizards.