Toxoplasmosis epidemic in a population of urbanised allied rock-wallabies (Petrogale assimilis) on Magnetic Island (Yunbenun), North Queensland.

A mortality event involving 23 allied rock-wallabies (Petrogale assimilis) displaying neurological signs and sudden death occurred in late April to May 2021 in a suburban residential area directly adjacent to Magnetic Island National Park, on Magnetic Island (Yunbenun), North Queensland, Australia. Three allied rock-wallabies were submitted for necropsy, and in all three cases, the cause of death was disseminated toxoplasmosis. This mortality event was unusual because only a small, localised population of native wallabies inhabiting a periurban area on a tropical island in the Great Barrier Reef World Heritage Area were affected. A disease investigation determined the outbreak was likely linked to the presence of free-ranging feral and domesticated cats inhabiting the area. There were no significant deaths of other wallabies or wildlife in the same or other parts of Magnetic Island (Yunbenun) at the time of the outbreak. This is the first reported case of toxoplasmosis in allied rock-wallabies (Petrogale assimilis), and this investigation highlights the importance of protecting native wildlife species from an infectious and potentially fatal parasitic disease.

A novel alphaherpesvirus and concurrent respiratory cryptococcosis in a captive koala (Phascolarctos cinereus).

A novel alphaherpesvirus was detected in a captive adult, lactating, female koala (Phascolarctos cinereus) admitted to James Cook University Veterinary Emergency Teaching & Clinical Hospital in March 2019, showing signs of anorexia and severe respiratory disease. Postmortem examination revealed gross pathology indicative of pneumonia. Histopathology demonstrated a chronic interstitial pneumonia, multifocal necrotising adrenalitis and hepatitis. Intranuclear inclusion bodies were detected by light microscopy in the respiratory epithelium of the bronchi, bronchioles, alveoli, and hepatocytes, biliary epithelium and adrenal gland associated with foci of necrosis. Cryptococcus gattii was isolated from fresh lung on necropsy, positively identified by PCR, and detected histologically by light microscopy, only in the lung tissue. A universal viral family-level PCR indicated that the virus was a member of the Herpesviruses. Sequence analysis in comparison to other known and published herpesviruses, indicated the virus was a novel alphaherpesvirus, with 97% nucleotide identity to macropodid alphaherpesvirus 1. We provisionally name the novel virus phascolarctid alphaherpesvirus 3 (PhaHV-3). Further research is needed to determine the distribution of this novel alphaherpesvirus in koala populations and establish associations with disease in this host species.

Epizootics of Streptococcus agalactiae infection in captive rays from Queensland, Australia.

The aim of this study was to describe two epizootics of high mortalities from infection with Streptococcus agalactiae, occurring in captive rays held in a marine display aquarium in south-east Queensland, Australia, in 2009 and 2010. Five different species of rays were affected, including mangrove whiprays (Himantura granulata), estuary rays (Dasyatis fluviorum), eastern shovelnose rays (Aptychotrema rostrata), white-spotted eagle rays (Aetobatus narinari) and blue-spotted mask rays (Neotrygon kuhlii). This report describes the history of both epizootics including collection, quarantine and husbandry of rays, the disease epizootics, clinico-pathological features of the disease, antimicrobial therapy, autogenous vaccine production, and laboratory studies including clinical and histopathology, bacteriology, PCR, molecular serotyping and sequencing of the bacterium S. agalactiae.

Natural outbreak of Streptococcus agalactiae (GBS) infection in wild giant Queensland grouper, Epinephelus lanceolatus (Bloch), and other wild fish in northern Queensland, Australia.

Ninety-three giant Queensland grouper, Epinephelus lanceolatus (Bloch), were found dead in Queensland, Australia, from 2007 to 2011. Most dead fish occurred in northern Queensland, with a peak of mortalities in Cairns in June 2008. In 2009, sick wild fish including giant sea catfish, Arius thalassinus (Rüppell), and javelin grunter, Pomadasys kaakan (Cuvier), also occurred in Cairns. In 2009 and 2010, two disease epizootics involving wild stingrays occurred at Sea World marine aquarium. Necropsy, histopathology, bacteriology and PCR determined that the cause of deaths of 12 giant Queensland grouper, three wild fish, six estuary rays, Dasyatis fluviorum (Ogilby), one mangrove whipray, Himantura granulata (Macleay), and one eastern shovelnose ray, Aptychotrema rostrata (Shaw), was Streptococcus agalactiae septicaemia. Biochemical testing of 34 S. agalactiae isolates from giant Queensland grouper, wild fish and stingrays showed all had identical biochemical profiles. The 16S rRNA gene sequences of isolates confirmed all isolates were S. agalactiae; genotyping of selected S. agalactiae isolates showed the isolates from giant Queensland grouper were serotype Ib, whereas isolates from wild fish and stingrays closely resembled serotype II. This is the first report of S. agalactiae from wild giant Queensland grouper and other wild tropical fish and stingray species in Queensland, Australia.

Toxoplasmosis in Indo-Pacific humpbacked dolphins (Sousa chinensis), from Queensland.

OBJECTIVE: To describe the clinical signs, gross pathology, serology, bacteriology, histopathology, electron microscopy and immunohistochemistry findings associated with toxoplasmosis in four Indo-Pacific humpbacked dolphins (Sousa chinensis) that stranded in Queensland in 2000 and 2001. DESIGN: Clinical assessment, gross necropsy, and laboratory examinations. PROCEDURE: Necropsies were performed on four S. chinensis to determine cause of death. Laboratory tests including serology, bacteriology, histopathology and transmission electron microscopy were done on the four dolphins. Immunohistochemistry was done on the brain, heart, liver, lung, spleen and adrenal gland from various dolphins to detect Toxoplasma gondii antigens. RESULTS: Necropsies showed all of four S. chinensis that stranded in Queensland in 2000 and 2001 had evidence of predatory shark attack and three were extremely emaciated. Histopathological examinations showed all four dolphins had toxoplasmosis with tissue cysts resembling T. gondii in the brain. Tachyzoite stages of T. gondii were detected in the lungs, heart, liver, spleen and adrenal gland, variously of all four dolphins. Electron microscopy studies and immunohistochemistry confirmed the tissues cysts were those of T. gondii. All four dolphins also had intercurrent disease including pneumonia, three had peritonitis and one had pancreatitis. CONCLUSION: Four S. chinensis necropsied in Queensland in 2000 and 2001 were found to be infected with toxoplasmosis. It is uncertain how these dolphins became infected and further studies are needed to determine how S. chinensis acquire toxoplasmosis. All four dolphins stranded after periods of heavy rainfall, and coastal freshwater runoff may be a risk factor for T. gondii infection in S. chinensis. This disease should be of concern to wildlife managers since S. chinensis is a rare species and its numbers appear to be declining.