Delving into the Aftermath of a Disease-Associated Near-Extinction Event: A Five-Year Study of a Serpentovirus (Nidovirus) in a Critically Endangered Turtle Population.

Bellinger River virus (BRV) is a serpentovirus (nidovirus) that was likely responsible for the catastrophic mortality of the Australian freshwater turtle Myuchelys georgesi in February 2015. From November 2015 to November 2020, swabs were collected from turtles during repeated river surveys to estimate the prevalence of BRV RNA, identify risk factors associated with BRV infection, and refine sample collection. BRV RNA prevalence at first capture was significantly higher in M. georgesi (10.8%) than in a coexisting turtle, Emydura macquarii (1.0%). For M. georgesi, various risk factors were identified depending on the analysis method, but a positive BRV result was consistently associated with a larger body size. All turtles were asymptomatic when sampled and conjunctival swabs were inferred to be optimal for ongoing monitoring. Although the absence of disease and recent BRV detections suggests a reduced ongoing threat, the potential for the virus to persist in an endemic focus or resurge in cyclical epidemics cannot be excluded. Therefore, BRV is an ongoing potential threat to the conservation of M. georgesi, and strict adherence to biosecurity principles is essential to minimise the risk of reintroduction or spread of BRV or other pathogens.

Nidoviruses in Reptiles: A Review.

Since their discovery in 2014, reptile nidoviruses (also known as serpentoviruses) have emerged as significant pathogens worldwide. They are known for causing severe and often fatal respiratory disease in various captive snake species, especially pythons. Related viruses have been detected in other reptiles with and without respiratory disease, including captive and wild populations of lizards, and wild populations of freshwater turtles. There are many opportunities to better understand the viral diversity, species susceptibility, and clinical presentation in different species in this relatively new field of research. In captive snake collections, reptile nidoviruses can spread quickly and be associated with high morbidity and mortality, yet the potential disease risk to wild reptile populations remains largely unknown, despite reptile species declining on a global scale. Experimental studies or investigations of disease outbreaks in wild reptile populations are scarce, leaving the available literature limited mostly to exploring findings of naturally infected animals in captivity. Further studies into the pathogenesis of different reptile nidoviruses in a variety of reptile species is required to explore the complexity of disease and routes of transmission. This review focuses on the biology of these viruses, hosts and geographic distribution, clinical signs and pathology, laboratory diagnosis and management of reptile nidovirus infections to better understand nidovirus infections in reptiles.

Prolonged Detection of Bovine Viral Diarrhoea Virus Infection in the Semen of Bulls.

Infection of bulls with bovine viral diarrhoea virus (BVDV) can result in the development of virus persistence, confined to the reproductive tract. These bulls develop a normal immune response with high neutralizing antibody titres. However, BVDV can be excreted in the semen for a prolonged period. Although relatively rare, in this study we describe six separate cases in bulls being prepared for admission to artificial breeding centres. Semen samples were tested in a pan-Pestivirus-reactive real-time PCR assay and viral RNA was detected in semen from five of the bulls for three to eight months after infection. In one bull, virus was detected at low levels for more than five years. This bull was found to have one small testis. When slaughtered, virus was only detected in the abnormal testis. The low levels of BVDV in the semen of these bulls were only intermittently detected by virus isolation in cell culture. This virus-contaminated semen presents a biosecurity risk and confirms the need to screen all batches of semen from bulls that have been previously infected with BVDV. The use of real-time PCR is recommended as the preferred laboratory assay for this purpose.

Squamous Cell Carcinoma in Two Wild Bell's Turtles (Myuchelys bellii).

Squamous cell carcinomas in Testudines are rarely reported. Most cases in the literature describe these tumors in captive animals. We report spontaneously arising squamous cell carcinomas affecting the plastron of two wild Bell's turtles (Myuchelys bellii) from the Macdonald River in New South Wales, Australia.

Diabetes screening in pregnancy failing women in rural Western Australia: An audit of oral glucose tolerance test completion rates.

OBJECTIVE: To quantify screening rate for gestational diabetes mellitus and completion of oral glucose tolerance test in rural and remote Western Australia. DESIGN AND PARTICIPANTS: Retrospective audit of 551 antenatal records from women of 16 years and older without pre-existing diabetes and with singleton pregnancies delivered in 2013. MAIN OUTCOME MEASURES: Number of women recorded screened for gestational diabetes mellitus in second or third trimester using oral glucose tolerance test or other tests; gestational diabetes mellitus rate. RESULTS: Only 278 (50.5%) women were screened with oral glucose tolerance test; 113 (20.5%) had no record of any screening related to gestational diabetes mellitus. In a nested mixed-effects logistic regression model, women with a previous gestational diabetes mellitus diagnosis, two or more risk factors (excluding ethnicity) or high-risk gestational diabetes mellitus ethnicity other than Australian Aboriginal were more likely to be screened, while Australian Aboriginal women were less likely to be screened with oral glucose tolerance test. Clinicians reported patient and clinician factors and logistical difficulties as reasons for the oral glucose tolerance test not being completed at their site. Of those screened with oral glucose tolerance test, a high rate of gestational diabetes mellitus was diagnosed (14.7% versus Western Australia state-wide average of 7.4%). CONCLUSION: Adherence to oral glucose tolerance test screening in rural Western Australia is inadequate for effective screening for gestational diabetes mellitus. Screening was not acceptable or available for a significant proportion of women at risk. Efforts to improve oral glucose tolerance test adherence and exploration of alternative gestational diabetes mellitus screening strategies are required.

Identification of a novel nidovirus as a potential cause of large scale mortalities in the endangered Bellinger River snapping turtle (Myuchelys georgesi).

In mid-February 2015, a large number of deaths were observed in the sole extant population of an endangered species of freshwater snapping turtle, Myuchelys georgesi, in a coastal river in New South Wales, Australia. Mortalities continued for approximately 7 weeks and affected mostly adult animals. More than 400 dead or dying animals were observed and population surveys conducted after the outbreak had ceased indicated that only a very small proportion of the population had survived, severely threatening the viability of the wild population. At necropsy, animals were in poor body condition, had bilateral swollen eyelids and some animals had tan foci on the skin of the ventral thighs. Histological examination revealed peri-orbital, splenic and nephric inflammation and necrosis. A virus was isolated in cell culture from a range of tissues. Nucleic acid sequencing of the virus isolate has identified the entire genome and indicates that this is a novel nidovirus that has a low level of nucleotide similarity to recognised nidoviruses. Its closest relatives are nidoviruses that have recently been described in pythons and lizards, usually in association with respiratory disease. In contrast, in the affected turtles, the most significant pathological changes were in the kidneys. Real time PCR assays developed to detect this virus demonstrated very high virus loads in affected tissues. In situ hybridisation studies confirmed the presence of viral nucleic acid in tissues in association with pathological changes. Collectively these data suggest that this virus is the likely cause of the mortalities that now threaten the survival of this species. Bellinger River Virus is the name proposed for this new virus.