Novel apicomplexan in the critically endangered Leadbeater's possum, Gymnobelideus leadbeateri

An unknown haemoparasite was detected on blood smears from two wild Leadbeater's possums brought into captivity for the purpose of joining the conservation breeding program. The parasite was identified as a novel apicomplexan using molecular techniques. Phylogenetic analyses grouped this parasite with other apicomplexans identified from Australian marsupials. Opportunistic and retrospective testing (PCR on blood or tissue and microscopic examination of blood smears) was undertaken on a total of 31 captive and wild individuals. Haemoparasites were detected in 44.4 % (95 % confidence interval [CI] 25.5-64.8) of blood smears and in 83.3 % (95 % CI 58.6-96.4) of blood and tissue samples tested by PCR. Duration in captivity at the time of testing was statistically significant, with decreasing odds of being PCR positive (OR = 0.95, 95 % CI 0.90-0.99; p = 0.043) and blood-smear positive (OR = 0.83, 95 % CI 0.69-0.99; p = 0.041) with increasing time (months) in captivity. A subset of animals that died was submitted for necropsy, but there was no histologic evidence of disease attributable to the haemoparasite identified. Given its apparent high prevalence in the population of Leadbeater's possum, without evidence of significant disease, this parasite is presumed to be endemic in this host species.