Dynamics of Antimicrobial Resistance Carriage in Koalas (Phascolarctos Cinereus) and Pteropid Bats (Pteropus Poliocephalus) Before, During and After Wildfires.

In the 2019-2020 summer, wildfires decimated the Australian bush environment and impacted wildlife species, including koalas (Phascolarctos cinereus) and grey headed flying fox pups (Pteropid bats, Pteropus poliocephalus). Consequently, hundreds of koalas and thousands of bat pups entered wildlife hospitals with fire-related injuries/illness, where some individuals received antimicrobial therapy. This study investigated the dynamics of antimicrobial resistance (AMR) in pre-fire, fire-affected and post-fire koalas and Pteropid bat pups.

Carriage of antibiotic resistance genes to treatments for chlamydial disease in koalas (): A comparison of occurrence before and during catastrophic wildfires.

Growing reports of diverse antibiotic resistance genes in wildlife species around the world symbolises the extent of this global One Health issue. The health of wildlife is threatened by antimicrobial resistance in situations where wildlife species develop disease and require antibiotics. Chlamydial disease is a key threat for koalas in Australia, with infected koalas frequently entering wildlife hospitals and requiring antibiotic therapy, typically with chloramphenicol or doxycycline.

Cutaneous and Respiratory Lesions in Bushfire-Affected Koalas.

In the wake of increasingly frequent bushfires emerging as a threat to wildlife worldwide, koalas have notably been the most rescued species in Australia. However, our understanding of burns and their severity in koalas is limited; hence, this study investigated the histopathological features and depth of burns in koala skin, as well as the presence of smoke-induced respiratory tract damage. In four bushfire-affected koalas that had been euthanised on welfare grounds, skin burns in various body regions were scored based on clinical appearance as superficial, partial thickness, or full thickness.

Individuality and stability of the koala () faecal microbiota through time.

Gut microbiota studies often rely on a single sample taken per individual, representing a snapshot in time. However, we know that gut microbiota composition in many animals exhibits intra-individual variation over the course of days to months. Such temporal variations can be a confounding factor in studies seeking to compare the gut microbiota of different wild populations, or to assess the impact of medical/veterinary interventions.

Genome Reference Assembly for Bottlenecked Southern Australian Koalas.

Koala populations show marked differences in inbreeding levels and in the presence or absence of the endogenous Koala retrovirus (KoRV). These genetic differences among populations may lead to severe disease impacts threatening koala population viability. In addition, the recent colonization of the koala genome by KoRV provides a unique opportunity to study the process of retroviral adaptation to vertebrate genomes and the impact this has on speciation, genome structure, and function.

Health and Diseases of Koalas.

The koala () is an arboreal marsupial that is found throughout much of eastern and southeastern Australia, and it relies primarily on eucalypt trees for food, water and shelter [...

An Analysis of Demographic and Triage Assessment Findings in Bushfire-Affected Koalas () on Kangaroo Island, South Australia, 2019-2020.

In the 2019-2020 Australian bushfires, Kangaroo Island, South Australia, experienced catastrophic bushfires that burnt approximately half the island, with an estimated 80% of the koala population lost. During and after the event, rescued koalas were triaged at a designated facility and a range of initial data were recorded including rescue location and date, sex, estimation of age, body condition and hydration, and assessment of burn severity ( = 304 records available). Koalas were presented to the triage facility over a span of 10 weeks, with 50.

TESTIS ABNORMALITIES IN A POPULATION OF SOUTH AUSTRALIAN KOALAS (PHASCOLARCTOS CINEREUS).

Testis asymmetry, in which the testes in an individual differ in size, has recently been reported in koalas (Phascolarctos cinereus) in the Mount Lofty Ranges population of South Australia. We describe the morphology and histology of both testes from affected individuals in this population (n=56) and the parameters of koalas with normal-sized testes based on age and breeding season (n=56). Morphologic measurements included testis weight, length, width, and volume; histologic parameters included seminiferous tubule diameter, seminiferous epithelial height, and seminiferous tubule (interstitial tissue ratio and presence or absence of spermatozoa).

Molecular Diagnosis of Koala Retrovirus (KoRV) in South Australian Koalas ().

Koala retrovirus, a recent discovery in Australian koalas, is endogenised in 100% of northern koalas but has lower prevalence in southern populations, with lower proviral and viral loads, and an undetermined level of endogenisation. KoRV has been associated with lymphoid neoplasia, e.g.

Pulmonary Actinomycosis in South Australian Koalas ().

Pneumonia has been reported in both free-ranging and captive koalas and a number of causative agents have been described. Between 2016 and 2019, 16 free-ranging and 1 captive koala () from the Mount Lofty Ranges of South Australia were identified with pyogranulomatous lobar pneumonia, which involved the left caudal lobe in 14/17 (82%) cases. Within lesions, numerous gram-positive or gram-variable, non-acid-fast filamentous bacteria were observed in association with Splendore-Hoeppli phenomenon.

Field immobilization using alfaxalone and alfaxalone-medetomidine in free-ranging koalas (Phascolarctos cinereus): a randomized comparative study.

Objective: To characterize and compare two intramuscular drug protocols using alfaxalone and alfaxalone-medetomidine combination for the field immobilization of free-ranging koalas.

Study Design: Blinded, randomized, comparative field study.

Animals: A total of 66 free-ranging koalas from the Mount Lofty Ranges, South Australia.

Koala retrovirus viral load and disease burden in distinct northern and southern koala populations.

Koala retrovirus (KoRV) displays features of both an endogenous and exogenous virus and is linked to neoplasia and immunosuppression in koalas. This study explores the apparent differences in the nature and impact of KoRV infection between geographically and genetically separated "northern" and "southern" koala populations, by investigating the disease status, completeness of the KoRV genome and the proviral (DNA) and viral (RNA) loads of 71 northern and 97 southern koalas. All northern animals were positive for all KoRV genes (gag, pro-pol and env) in both DNA and RNA forms, whereas many southern animals were missing one or more KoRV genes.

CHANGES IN ANTIOXIDANT CAPACITY OF KOALAS () BASED ON HEALTH STATUS AND MEASUREMENT OF THE ANTIOXIDANT ASCORBATE IN EUCALYPT LEAVES.

Antioxidants have a crucial role in protecting the body from oxidative stress, which would otherwise result in cellular damage and possibly predispose animals to disease. The antioxidant capacity of koalas () and its association with health or disease status is currently unknown. Ascorbate, a dietary antioxidant, has previously been identified in a few eucalypt species eaten by koalas.

Genetic diversity of Koala retrovirus gene subtypes: insights into northern and southern koala populations.

Koala retrovirus (KoRV) is a recently endogenized retrovirus associated with neoplasia and immunosuppression in koala populations. The virus is known to display sequence variability and to be present at varying prevalence in different populations, with animals in southern Australia displaying lower prevalence and viral loads than northern animals. This study used a PCR and next-generation sequencing strategy to examine the diversity of the KoRV gene in both proviral DNA and viral RNA forms in two distinct populations representative of the 'northern' and 'southern' koala genotypes.

Prevalence and clinical significance of koala retrovirus in two South Australian koala (Phascolarctos cinereus) populations.

Purpose: Koala retrovirus (KoRV-A) is 100  % prevalent in northern Australian (Queensland and New South Wales) koala populations, where KoRV-B has been associated with Chlamydia pecorum disease and the development of lymphosarcoma. In southern populations (Victoria and South Australia), KoRV-A is less prevalent and KoRV-B has not been detected in Victoria, while the current prevalence in South Australian populations is unknown but is thought to be low. This study aimed to determine (i) the prevalence of KoRV in the two largest South Australian koala populations [Kangaroo Island (KI) and Mount Lofty Ranges (MLR)], (ii) KoRV subtype and (iii) if an association between KoRV and C.

Chlamydia pecorum prevalence in South Australian koala (Phascolarctos cinereus) populations: Identification and modelling of a population free from infection.

Chlamydia pecorum is an established and prevalent infection that produces severe clinical disease in many koala populations, contributing to dramatic population declines. In wild South Australian koala populations, C. pecorum occurrence and distribution is unknown.

PREVALENCE AND PATHOLOGIC FEATURES OF CHLAMYDIA PECORUM INFECTIONS IN SOUTH AUSTRALIAN KOALAS (PHASCOLARCTOS CINEREUS).

Chlamydia pecorum infection is highly prevalent in many koala ( Phascolarctos cinereus ) populations in the eastern states of Australia, causing ocular and urogenital tract disease. In contrast, the current prevalence of chlamydiosis in South Australian (SA) koalas is largely unknown, with few reports of clinical cases. We examined 65 SA rescued wild koalas at necropsy and collected ocular and urogenital swabs for the detection of C.

Genetic diversity in the plasticity zone and the presence of the chlamydial plasmid differentiates Chlamydia pecorum strains from pigs, sheep, cattle, and koalas.

Background: Chlamydia pecorum is a globally recognised pathogen of livestock and koalas. To date, comparative genomics of C. pecorum strains from sheep, cattle and koalas has revealed that only single nucleotide polymorphisms (SNPs) and a limited number of pseudogenes appear to contribute to the genetic diversity of this pathogen.

Plasma biochemistry and urinalysis variables of koalas (Phascolarctos cinereus) with and without oxalate nephrosis.

Background: Oxalate nephrosis is a highly prevalent disease in the Mount Lofty Ranges koala population in South Australia, but associated clinicopathologic findings remain undescribed.

Objectives: The aims of this study were to determine plasma biochemical and urinalysis variables, particularly for renal function and urinary crystal morphology and composition, in koalas with oxalate nephrosis.

Methods: Blood and urine samples from Mount Lofty Ranges koalas with oxalate nephrosis were compared with those unaffected by renal oxalate crystal deposition from Mount Lofty and Kangaroo Island, South Australia and Moggill, Queensland.