A mortality event associated with toxoplasmosis in macropods in rehabilitative care in Australia

A mortality event of 19 wild macropod joeys in rehabilitative care over 3 months associated with toxoplasmosis is described. Clinical signs included dyspnoea, inappetence, lethargy or sudden death. 17 out of 19 joeys died within hours to days following onset of clinical signs while 2 joeys sustained severe rapid weight loss over a week before their death. Two juvenile eastern grey kangaroos were submitted for post-mortem at the Charles Sturt University Veterinary Diagnostics Laboratory where severe toxoplasmosis was diagnosed. The ten surviving cohabiting joeys were sampled for modified agglutination and immunofluorescent toxoplasma antibody testing. Toxoplasmosisis widely reported as a significant disease of captive native Australian marsupials due to its high morbidity and mortality. Marsupials are aberrant hosts of the protist apicomplexan parasite Toxoplasma gondii. Sporozoite ingestion leads to formation of rapidly dividing tachyzoite cysts or slowly replicating bradyzoite cysts in tissues, notably in the central nervous system,and accompanying inflammation typically results in significant neurological clinical signs. The only known definitive host of T. gondii are felids,and in Australia is Felis felis, the domestic cat. Sporulated oocyts shed by cats are highly resistant in the environment. Toxoplasmosis epizootics though reported, are scarce, this report reinforces the susceptibility of macropods to T. gondii and questions the methods of transmission in populations of marsupials.