Prevalence and pathological findings associated with Chlamydia pecorum and koala retrovirus infections in South Australian koala populations

Two infectious pathogens contributing to northern Australian (Queensland and New South Wales) population declines are Chlamydia pecorum and koala retrovirus (KoRV). C. pecorum infection causes conjunctivitis and blindness, urinary tract infections or reproductive tract disease causing infertility. In northern populations, KoRV-A is 100% prevalent and an active endogenous virus. High KoRV viral load and exogenous KoRV-B have been associated with lymphosarcoma and chlamydial disease. In South Australia (SA), less is known about C. pecorum and KoRV prevalence and disease, though early evidence has suggested that chlamydial disease is less severe and KoRV prevalence is low. SA koalas may therefore provide an opportunity to further investigate the association of KoRV with disease. The prevalence of C. pecorum and KoRV was determined in wild-caught SA koalas. The Kangaroo Island (KI) population was shown to be C. pecorum-free by qPCR (n=170) and in historical clinical data (n=13,000). In the Mount Lofty Ranges (MLR), 46.7% (35/75) of koalas were C. pecorum positive, and whilst only 4.0% (3/75) were observed with disease, C. pecorum infection was significantly associated with female reproductive inactivity. The prevalence of KoRV in KI and MLR was 42.4% (72/170) and 65.3% (49/75), respectively and only KoRV-A and not KoRV-B was detected by PCR. The median (range) KoRV proviral load in KI and MLR was low, at 113 (2- 12,641) and 35 (1- 574) copies/103 β-actin copies, respectively. There was no association between C. pecorum infection or disease and KoRV provirus, however koalas with concurrent infections were over three times more likely to develop chlamydial disease. Subclinical C. pecorum and KoRV infections were shown to have no effect on haematology values, allowing for the development of the first southern koala haematology reference intervals (n=138). An extensive comparative pathological investigation was conducted on KoRV-positive koalas from the MLR (n=92) and Queensland (n=67). Lymphosarcoma was observed in 4.3% (4/92) of MLR and 7.5% (5/67) of Queensland koalas, with the same morphology and high KoRV proviral and viral loads, that may suggest common oncogenic pathways. Ocular chlamydial disease was severe in both populations, but urinary tract disease was less severe in MLR. There was no association between chlamydial disease severity or load and KoRV proviral load, but in MLR there was a positive correlation between chlamydial disease severity and KoRV viral load. In both populations, KoRV proviral and viral loads were positively correlated with lymphocyte and metarubricyte counts and negatively correlated with erythrocyte and neutrophil counts which may suggest that KoRV can infect bone marrow and disrupting cellular differentiation. KoRV viral load was positively correlated with splenic lymphoid area suggesting that spleen may also be a site for KoRV replication. The prevalence of C. pecorum and KoRV in mainland SA was higher than expected and severe chlamydial disease and lymphoid neoplasia do occur. No clear association between C. pecorum disease and KoRV were identified, however KoRV infection appears to be highly complex and differs between northern and southern populations. Southern populations with a reduced prevalence of disease may therefore ensure the longevity of the species.Thesis (Ph.D.) -- University of Adelaide, School of Animal and Veterinary Sciences, 201

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. There was a significant relationship between the completeness of the KoRV genome and clinical status in this population. The proviral and viral loads of the northern population were significantly higher than those of the southern population (P

Genetic diversity of Koala retrovirus (KoRV) env gene subtypes: Insights into northern and southern koala populations

Koala retrovirus (KoRV) is a recently endogenised 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 env gene in both proviral DNA and viral RNA forms in two distinct populations representative of the “northern” and “southern” koala genotypes. The current study demonstrated that the full range of KoRV subtypes is present across both populations, and in both healthy and sick animals. KoRV-A was the predominant proviral subtype in both populations, but there was marked diversity of DNA and RNA subtypes within individuals. Many of the northern animals displayed a higher RNA viral diversity than evident in their proviral DNA, indicating relatively higher replication efficiency of non-KoRV-A subtypes. The southern animals displayed a lower absolute copy number of KoRV than the northern animals as reported previously and a higher preponderance of KoRV-A in individual animals. These discrepancies in viral replication and diversity remain unexplained but may indicate relative protection of the southern population from KoRV replication due to either viral or host factors and may represent an important protective effect for the host in KoRV’s ongoing entry into the koala genome

EuReCa ONE—27 Nations, ONE Europe, ONE Registry A prospective one month analysis of out-of-hospital cardiac arrest outcomes in 27 countries in Europe

AbstractIntroductionThe aim of the EuReCa ONE study was to determine the incidence, process, and outcome for out of hospital cardiac arrest (OHCA) throughout Europe.MethodsThis was an international, prospective, multi-centre one-month study. Patients who suffered an OHCA during October 2014 who were attended and/or treated by an Emergency Medical Service (EMS) were eligible for inclusion in the study. Data were extracted from national, regional or local registries.ResultsData on 10,682 confirmed OHCAs from 248 regions in 27 countries, covering an estimated population of 174 million. In 7146 (66%) cases, CPR was started by a bystander or by the EMS. The incidence of CPR attempts ranged from 19.0 to 104.0 per 100,000 population per year. 1735 had ROSC on arrival at hospital (25.2%), Overall, 662/6414 (10.3%) in all cases with CPR attempted survived for at least 30 days or to hospital discharge.ConclusionThe results of EuReCa ONE highlight that OHCA is still a major public health problem accounting for a substantial number of deaths in Europe.EuReCa ONE very clearly demonstrates marked differences in the processes for data collection and reported outcomes following OHCA all over Europe. Using these data and analyses, different countries, regions, systems, and concepts can benchmark themselves and may learn from each other to further improve survival following one of our major health care events

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. pecorum exists.Methodology. Wild koalas were sampled in KI (n = 170) between 2014 and 2017 and in MLR (n = 75) in 2016. Clinical examinations were performed, with blood collected for KoRV detection and typing by PCR.Results. KoRV prevalence was 42.4 % [72/170, 95 % confidence interval (CI): 34.9-49.8 %] in KI and 65.3 % (49/ 75, 95 % CI: 54.6-76.1 %) in MLR. Only KoRV-A, and not KoRV-B, was detected in both populations. In MLR, there was no statistical association between KoRV and C. pecorum infection (P = 0.740), or KoRV and C. pecorum disease status (P=0.274), although KoRV-infected koalas were more likely to present with overt C. pecorum disease than subclinical infection (odds ratio: 3.15, 95 % CI: 0.91-5.39).Conclusion. KoRV-A is a prevalent pathogen in wild South Australian koala populations. Future studies should continue to investigate KoRV and C. pecorum associations, as the relationship is likely to be complex and to differ between the northern and southern populations