The Australian fur seal (Arctocephalus pusillus doriferus) has experienced a slower than expected population recovery since the end of the commercial sealing era, with a high third trimester abortion rate. There is currently no known proximate cause. Coxiella burnetii (Cb) is a well-known cause of abortion in domestic and wildlife species and an important zoonotic pathogen. It has been recorded from a small number of northern hemisphere marine mammals and may be a potential contributory factor to decreasing populations of northern fur seals (Callorhinus ursinus) and Steller sealions (Eumetopias jubatus). It has not been recorded from marine mammals in the southern hemisphere but is well documented in ruminants and wildlife in Australia as a cause of reproductive failure. Third trimester aborted fetuses (n = 46) and full-term placentas (n = 66) from Australian fur seals, were collected on Kanowna Island and Seal Rocks in Bass Strait, south-eastern Australia. Utilizing routine hematoxylin and eosin histopathology, Cb immunohistochemistry and two different qPCR targets–htpAB and com1, Cb was identified. Routine histopathology and immunohistochemistry were insensitive for the detection of Cb. The detected Cb prevalence ranged from 10.6% for com1 up to 40.9% with htpAB. Coxiella burnetti was readily detected in full-term placentas but in aborted fetal material only in a single placenta associated with a still birth. The exact significance is currently unclear, but this highlights that Cb is present in Australian fur seals, breeding in Bass Strait. Bass Strait is in one of the world’s fastest warming oceanic regions and marine mammals breeding in the area are likely to be key indicators of marine ecosystem stressors. This first description of Cb in a marine mammal from the southern hemisphere, highlights the need to further investigate the potential risks this pathogen poses to Australian fur seals and sympatric marine mammals. Additionally, it is important to determine the zoonotic risk of this pathogen to persons working with, and in proximity of, Australian fur seal breeding colonies.

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Kangaroos are considered to be an important reservoir of Q fever in Australia, although there is limited knowledge on the true prevalence and distribution of coxiellosis in Australian macropod populations. Serological tests serve as useful surveillance tools, but formal test validation is needed to be able to estimate true seroprevalence rates, and few tests have been validated to screen wildlife species for Q fever.

Wobbly possum disease virus (WPDV) is an arterivirus that was originally identified in common brushtail possums (Trichosurus vulpecula) in New Zealand, where it causes severe neurological disease. In this study, serum samples (n = 188) from Australian common brushtail, mountain brushtail (Trichosurus cunninghami) and common ringtail (Pseudocheirus peregrinus) possums were tested for antibodies to WPDV using ELISA. Antibodies to WPDV were detected in possums from all three species that were sampled in the states of Victoria and South Australia. Overall, 16% (30/188; 95% CI 11.0-22.0) of possums were seropositive for WPDV and 11.7% (22/188; 95% CI 7.5-17.2) were equivocal. The frequency of WPDV antibody detection was the highest in possums from the two brushtail species. This is the first reported serological evidence of infection with WPDV, or an antigenically similar virus, in Australian possums, and the first study to find antibodies in species other than common brushtail possums. Attempts to detect viral RNA in spleens by PCR were unsuccessful. Further research is needed to characterise the virus in Australian possums and to determine its impact on the ecology of Australian marsupials.