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Context: The disease toxoplasmosis, caused by infection with the intra-cellular protozoan parasite Toxoplasma gondii , is a potential threat to the conservation of some endothermic vertebrates. Toxoplasmosis has been reported to cause disease and acute death in many marsupials, including endangered bandicoots. Methods are required to quantify the environmental contamination with T. gondii and, hence, assess the relative threat it poses to resident species. A multi-modal approach to assess an environment for the presence of pathogens increases the likelihood of a more accurate estimate of the level of contamination and inferred risk of infection to target species. Aim: This project aimed to use a multi-modal approach to estimate the environmental contamination with T. gondii across two separate landscapes with differing cat populations in the northern hinterland of Western Port, Victoria, Australia. Methods: The following four parameters were used: the presence of IgG antibodies to T. gondii in free-ranging southern brown bandicoots (Isoodon obesulus) using the modified agglutination test (MAT); the presence of T. gondii DNA in the tissues of free-ranging rabbits (Oryctolagus cuniculus) and mice (Mus musculus) by real-time quantitative polymerase chain reaction (qPCR); and the presence of T. gondii oocysts in the soil using filtration methods and real-time qPCR. Key results: Toxoplasma gondii was not identified in any of the soil samples (n = 594), southern brown bandicoots (n = 24) or mice (n = 267). Only one rabbit tested positive for T. gondii (n = 118). Conclusions: The tests across soils and three different mammalian species all delivered similar results, leading to the conclusion that the landscapes measured had low T. gondii contamination at the time of assessment. Implications: This Australian study is the first to show that the use of pathogen detection in target and two sentinel species, combined with soil analysis, may be a useful approach to assess the environmental risk of T. gondii infection in endangered and vulnerable species. Further research is recommended across sites with a gradient of T. gondii contamination and into the use of other sentinel species. Further refining of techniques for direct soil analysis in Australian conditions is recommended. Information about environmental contamination with Toxoplasma gondii can inform management decisions of risk of toxoplasmosis in resident endothermic vertebrates and in potential translocations and re-introductions of endangered species. This work estimated environmental contamination across two different landscapes. Both the landscapes measured had low T. gondii contamination. The results highlighted the potential of using sentinel species (rabbits and mice), target species (bandicoots) and soil analysis to enhance the detection and inform likely exposure of a target species to T. gondii in a defined landscape. Photograph by Amanda Jane Breidahl. [ABSTRACT FROM AUTHOR]

Telemetry neck collars are commonly used to collect spatial data on free ranging animals. Two major challenges in application are entanglement prevention and retrieval of the collars after the study. Weak links made of a degradable material that breaks down while deployed on the animal are a potential solution to reduce entanglement and prevent the need to capture or sedate animals for retrieval. However, weak links can perform inconsistently depending on an animal's behaviour and environmental factors such as heat and humidity. A study of disease in eastern grey kangaroos (Macropus giganteus) in Victoria, Australia, provided an opportunity to test the performance of 35 radio collars fitted with a latex weak link between May and July 2022. At the conclusion of the study, 20 collars were manually removed from euthanised animals, and 15 detached in the field; all of these broke at the weak link. Of the 15 detached collars, 10 dropped from live animals due to degradation between 106 and 208 days (mean = 147 days) after deployment, four kangaroos were found dead and their collars were retrieved nearby and one dropped immediately after attachment. The performance of the device in this study demonstrates the utility of weak links as a cheap and simple remote detachment tool to prevent entanglement and achieve remote detachment of neck collars during animal tracking studies. Weak links installed on radio collars are devices designed to protect animals from entanglement during animal studies and allow remote retrieval of the collar after study. We tested a latex weak link on collars used to track eastern grey kangaroos and found that it was able to successfully achieve both functions on all animals. Future researchers can use weak links of similar design to provide good welfare for animals involved in research. Photograph by Tian Chen. [ABSTRACT FROM AUTHOR]

Chronic phalaris toxicity (CPT) is a neurological disease caused by animals ingesting toxins produced by early growth stages of Phalaris aquatica, a pasture plant introduced to the southeastern regions of Australia post colonization. Little is known about the clinical progression of CPT in wildlife, as incidents are sporadic and predominantly reported when animals are in the end stages of disease and in a poor welfare state. We studied a cohort of 35 eastern gray kangaroos (Macropus giganteus) affected by CPT to clarify clinical prognosis and survival rates. Kangaroos were captured in May, June, and July of 2022 at Plenty Gorge Parklands, Victoria, Australia. Each animal was radiotracked for 180 d, clinical progression and disease outcomes monitored twice a week. By the conclusion of the study, 24 animals had died (19 by euthanasia due to deterioration, five found dead). Ten animals survived, with two demonstrating a reduction in clinical signs and eight showing full resolution of clinical signs. One animal was disqualified from the study. The overall survival rate was 29.4% (95% confidence interval 17.5–49.5%). The survival duration of animals that died ranged from 5 to 133 d. There was no difference in survival rate based on sex (P¼0.2), age class (P¼0.49) or the month of capture (P¼0.49). These results suggest that CPT is an important health and welfare concern for at- risk macropod populations, with high case-fatality rates and prolonged clinical durations. Further research to manage the disease via methods such as reducing Phalaris aquatica plant coverage and preventative treatments for animals is warranted to reduce disease incidences and improve disease outcomes in wildlife populations. [ABSTRACT FROM AUTHOR]

The intracellular pathogens Toxoplasma gondii, Brucella spp., and Chlamydia spp. are all known causative agents of abortion in wildlife. Both T. gondii and Brucella spp. have been identified in marine mammal abortions and a limited number of studies have detected their potential presence in Australian fur seals (Arctocephalus pusillus doriferus), but data are sparse for these pathogens in Australian fur seal breeding colonies. Australian fur seals have been shown to have a high degree of third-trimester pregnancy loss in one of their largest breeding colonies. Additionally, pup production has declined at the largest breeding colony for the species. This study surveyed the presence of T. gondii, Brucella spp., and Chlamydia spp. as potential infectious causes of this reproductive loss. Aborted fetuses were collected from two of the largest breeding colonies for the species, Seal Rocks (n=19) and Kanowna Island (n=34). These were examined grossly and through histopathological evaluation, in conjunction with molecular testing for all three pathogens. Placentas were collected from full-term births during the pupping season from Kanowna Island (n=118). These were used to compare the molecular prevalence of the three pathogens in presumed successful pregnancies. Chlamydia spp. was not detected in aborted fetuses in this study. Brucella spp. was detected with PCR in both aborted fetuses (9.4%) and placentas from full-term births (3.4%), and T. gondii was detected using routine histopathology (n=2/53), immunohistochemistry (n=3/4), and PCR (n=4/53) in tissues from aborted fetuses. Toxoplasma gondii was present in 7.5% of third-trimester abortions and absent from all full-term placentas. Brucella spp. was detected in both aborted fetuses and full-term placentas. This is the first description of vertical transmission of T. gondii in a marine mammal from the southern hemisphere. [ABSTRACT FROM AUTHOR]

There is growing worldwide recognition of the threat posed by persistent organic pollutants (POPs) to wildlife populations. We aimed to measure exposure levels to POPs in a Southern Hemisphere aquatic waterbird species, the nomadic gray teal (Anas gracilis), which is found across Australia. We collected wings from 39 ducks harvested by recreational hunters at two sites (one coastal, one inland) in Victoria, southeastern Australia, in 2021. We examined three groups of POPs: nine congeners of polychlorinated biphenyls (PCBs), 13 organochlorine pesticides (OCPs), and 12 polycyclic aromatic hydrocarbons (PAHs). The PCBs, OCPs, and PAHs were detected at quantifiable levels in 13%, 72%, and 100% of birds, respectively. Of the congeners we tested for in PCBs, OCPs, and PAHs, 33%, 38%, and 100% were detected at quantifiable levels, respectively. The highest levels of exposure to POPs that we found were to the PAH benzo[b]fluoranthene, occurring at a concentration range of 1.78 to 161.05 ng/g wet weight. There were some trends detected relating to differences between geographical sites, with higher levels of several PAHs at the coastal versus inland site. There were several strong, positive associations among PAHs found. We discuss potential sources for the POPs detected, including industrial and agricultural sources, and the likely role of large‐scale forest fires in PAH levels. Our results confirm that while Australian waterbirds are exposed to a variety of POPs, exposure levels are currently relatively low. Additional future investigations are required to further characterize POPs within Australian waterbird species. Environ Toxicol Chem 2024;43:736–747. © 2023 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC. [ABSTRACT FROM AUTHOR]

Eastern barred bandicoots (Perameles gunnii) are thought to be highly susceptible to disease caused by infection with the protozoan parasite Toxoplasma gondii. This study followed a population of 67 P. gunnii introduced onto the Summerland Peninsula, Phillip Island, Australia, where the prevalence of T. gondii infection in the feral cat population was known to be very high. Prior to release, bandicoots were tested for serologic exposure to T. gondii using the modified agglutination test. A subset of bandicoots was tested on four occasions after release onto the peninsula. No seroconversion was detected at any time point. A subset of bandicoots was radiotracked after release and at two additional trapping sessions to help monitor survival. Toxoplasma gondii DNA was not detected by PCR in eight carcasses recovered for necropsy. Fourteen founder bandicoots (21% of founders) were known to be alive at 500 d post-release. A total of 29 unmarked bandicoots were trapped over the study period, confirming that the bandicoots were successfully reproducing on the island. Body weight, packed cell volume, and total plasma protein were used as measures of individual animal health; population health was inferred from these data. Body weight was significantly associated with trip number, with a general trend of increasing weight after release onto the island. This study showed that eastern barred bandicoots were able to establish a new population despite a probably high environmental load of T. gondii. [ABSTRACT FROM AUTHOR]

Context: Coxiella burnetii is suspected as a novel pathogen contributing to decreased pup production in Australian fur seals (Arctocephalus pusillus doriferus). It has recently been described from a single breeding colony in Bass Strait, has previously been associated with two decreasing populations of northern hemisphere pinnipeds and is a known reproductive pathogen. Data around its disease ecology in marine mammals are sparse. Aims: To determine whether environmental DNA (eDNA) can be used to survey for C. burnetii in Australian fur seal breeding colonies. To determine whether C. burnetii in Australian fur seals is the same genotype as terrestrial Australian C. burnetii. Methods: Soil samples were collected from Kanowna Island and Seal Rocks. Placental samples were collected from Kanowna Island. Soil was evaluated for eDNA using a quantitative polymerase chain reaction (qPCR) for com1 gene. Placental samples were evaluated with com1 , htpAB and IS1111 markers. Multiple-locus variable number of tandem repeats analysis for three microsatellite loci (ms-24, ms-28 and ms-33) was used to determine relatedness to Australian C. burnetii genotypes. Key results: eDNA results varied between pre-and post-pupping at Seal Rocks. When targeting the com1 gene, the post-pupping prevalence at Kanowna Island and Seal Rocks was 59.6% and 90%, respectively. eDNA PCR inhibition of samples was low at 1.9%. There was very poor, sporadic to absent IS1111 amplification in placental samples. The com1 and htpAB qPCRs had an overall prevalence across placental samples of 39.2% and 56.7% respectively. In 90.1% of placental samples (n = 11), the ms-28 locus amplified. Neither ms-24 nor ms-33 amplified. Conclusions: eDNA is an effective tool to survey Australian fur seal breeding colonies in the post-pupping period for C. burnetii. The prevalence appears to be much higher in the Seal Rocks colony than in the Kanowna Island colony. It appears that this is not a terrestrial Australian genotype but rather closely related to genotypes detected in marine mammals in the northern hemisphere. Implications: This research significantly expands our ability to survey for C. burnetii in Australian fur seals and other marine mammals. It highlights knowledge gaps in our understanding of the disease ecology and phylogeny of C. burnetii in marine mammals. Infectious diseases such as Q-fever (Coxiella) often contribute to reproductive failure in terrestrial mammals. We investigated whether this pathogen could be detected in the environment and in Australian fur seal placentas by using molecular techniques. Our results indicated that Coxiella burnetii is present in two of the largest breeding colonies and that environmental DNA can be used to survey for infected colonies. Photograph by Hanna Geeson. [ABSTRACT FROM AUTHOR]

Toxoplasma gondii is a ubiquitous protozoan transmitted by felids and infection, morbidity, and mortality occur in numerous marsupial species. This study explores the relationship between cat exposure and Toxoplasma in burrowing bettongs (Bettongia lesueur) in the Arid Recovery Reserve (ARR), South Australia. We estimated seroprevalence, using a modified agglutination test for T. gondii -specific immunoglobulins, in cat-free and cat-exposed bettong populations. Tissue samples collected opportunistically from bettong carcasses and from cats within and around the reserve were screened for T. gondii DNA using multiplex real-time polymerase chain reaction (M-qPCR). Two cats trapped inside the ARR tested positive (50.0%; 95% CI: 15.0–85.0%). All bettongs tested from the cat-free (n = 48) and cat-exposed (n = 19) exclosures were seronegative (95% CI: 0–7.41% and 0–16.82% respectively). We found no evidence of fatal toxoplasmosis, with all bettong carcasses negative on M-qPCR (n = 11). We propose that T. gondii was not detected in bettongs coexisting with cats primarily due to low exposure of bettongs at the time of sampling, possibly due to poor oocyst viability in arid conditions or low shedding by cats. Ongoing screening throughout high and low rainfall years should be conducted to better establish the risk of Toxoplasma to bettongs in the ARR. The burrowing bettong (Bettongia lesueur) has suffered drastic population declines since the introduction of cats to Australia. We surveyed bettongs inhabiting the Arid Recovery Reserve (South Australia) to investigate whether animals coexisting with cats were at an increased risk of infection with Toxoplasma gondii , a parasite transmitted by felids that causes disease in many species. We found no evidence of infection; however, ongoing testing of this valuable reintroduced population is recommended. Photograph by Philippa McKay. [ABSTRACT FROM AUTHOR]