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Mahalingam S.,Griffith University | Herrero L.J.,Griffith University | Playford E.G.,University of Queensland | Spann K.,University of Queensland | And 7 more authors.
The Lancet Infectious Diseases | Year: 2012

Hendra virus, first identified in 1994 in Queensland, is an emerging zoonotic pathogen gaining importance in Australia because a growing number of infections are reported in horses and people. The virus, a member of the family Paramyxoviridae (genus Henipavirus), is transmitted to horses by pteropid bats (fruit bats or flying foxes), with human infection a result of direct contact with infected horses. Case-fatality rate is high in both horses and people, and so far, more than 60 horses and four people have died from Hendra virus infection in Australia. Human infection is characterised by an acute encephalitic syndrome or relapsing encephalitis, for which no effective treatment is currently available. Recent identification of Hendra virus infection in a domestic animal outside the laboratory setting, and the large range of pteropid bats in Australia, underpins the potential of this virus to cause greater morbidity and mortality in both rural and urban populations and its importance to both veterinary and human health. Attempts at treatment with ribavirin and chloroquine have been unsuccessful. Education, hygiene, and infection control measures have hitherto been the mainstay of prevention, while access to monoclonal antibody treatment and development of an animal vaccine offer further opportunities for disease prevention and control. © 2012 Elsevier Ltd. Source


McFarlane R.,Australian National University | Becker N.,Australian National University | Field H.,Queensland Center for Emerging Infectious Diseases
PLoS ONE | Year: 2011

Hendra virus is a recently emerged bat-borne zoonotic agent with high lethality in horses and humans in Australia. This is a rare disease and the determinants of bat to horse transmission, including the factors that bring these hosts together at critical times, are poorly understood. In this cross-disciplinary study climatic and vegetation primary productivity variables are compared for the dispersed and heterogenic 1994-2010 outbreak sites. The significant occurrence of spillover events within the dry season (p = 0.013, 95% CI (0.57-0.98)) suggests seasonal forcing of transmission across species, or seasonal forcing of virus excretion by the reservoir host. We explore the evidence for both. Preliminary investigations of the spatial determinants of Hendra disease locations are also presented. We find that postal areas in the Australian state of Queensland in which pteropid fruit bat (flying fox) roosts occur are approximately forty times more likely (OR = 40.5, (95% CI (5.16, 317.52)) to be the location of Hendra spillover events. This appears to be independent of density of horses at these locations. We consider issues of scale of host resource use, land use change and limitations of existing data that challenge analysis and limit further conclusive outcomes. This investigation of a broad range of potential climatic and environmental influences provides a good base for future investigations. Further understanding of cross-species Hendra virus transmission requires better understanding of flying fox resource use in the urban-rural landscape. © 2011 McFarlane et al. Source


Tozer S.J.,University of Queensland | Lambert S.B.,University of Queensland | Strong C.L.,Griffith University | Field H.E.,Queensland Center for Emerging Infectious Diseases | And 3 more authors.
Zoonoses and Public Health | Year: 2014

Q fever is a vaccine-preventable disease; despite this, high annual notification numbers are still recorded in Australia. We have previously shown seroprevalence in Queensland metropolitan regions is approaching that of rural areas. This study investigated the presence of nucleic acid from Coxiella burnetii, the agent responsible for Q fever, in a number of animal and environmental samples collected throughout Queensland, to identify potential sources of human infection. Samples were collected from 129 geographical locations and included urine, faeces and whole blood from 22 different animal species; 45 ticks were removed from two species, canines and possums; 151 soil samples; 72 atmospheric dust samples collected from two locations and 50 dust swabs collected from domestic vacuum cleaners. PCR testing was performed targeting the IS1111 and COM1 genes for the specific detection of C. burnetii DNA. There were 85 detections from 1318 animal samples, giving a detection rate for each sample type ranging from 2.1 to 6.8%. Equine samples produced a detection rate of 11.9%, whilst feline and canine samples showed detection rates of 7.8% and 5.2%, respectively. Native animals had varying detection rates: pooled urines from flying foxes had 7.8%, whilst koalas had 5.1%, and 6.7% of ticks screened were positive. The soil and dust samples showed the presence of C. burnetii DNA ranging from 2.0 to 6.9%, respectively. These data show that specimens from a variety of animal species and the general environment provide a number of potential sources for C. burnetii infections of humans living in Queensland. These previously unrecognized sources may account for the high seroprevalence rates seen in putative low-risk communities, including Q fever patients with no direct animal contact and those subjects living in a low-risk urban environment. © 2013 Blackwell Verlag GmbH. Source


Breed A.C.,University of Queensland | Breed A.C.,Animal Health and Veterinary Laboratories Agency | Breed M.F.,University of Adelaide | Meers J.,University of Queensland | Field H.E.,Queensland Center for Emerging Infectious Diseases
PLoS ONE | Year: 2011

This study investigated the seroepidemiology of Hendra virus in a spectacled flying-fox (Pteropus conspicillatus) population in northern Australia, near the location of an equine and associated human Hendra virus infection in late 2004. The pattern of infection in the population was investigated using a serial cross-sectional serological study over a 25-month period, with blood sampled from 521 individuals over six sampling sessions. Antibody titres to the virus were determined by virus neutralisation test. In contrast to the expected episodic infection pattern, we observed that seroprevalence gradually increased over the two years suggesting infection was endemic in the population over the study period. Our results suggested age, pregnancy and lactation were significant risk factors for a detectable neutralizing antibody response. Antibody titres were significantly higher in females than males, with the highest titres occurring in pregnant animals. Temporal variation in antibody titres suggests that herd immunity to the virus may wax and wane on a seasonal basis. These findings support an endemic infection pattern of henipaviruses in bat populations suggesting their infection dynamics may differ significantly from the acute, self limiting episodic pattern observed with related viruses (e.g. measles virus, phocine distemper virus, rinderpest virus) hence requiring a much smaller critical host population size to sustain the virus. These findings help inform predictive modelling of henipavirus infection in bat populations, and indicate that the life cycle of the reservoir species should be taken into account when developing risk management strategies for henipaviruses. © 2011 Breed et al. Source


Hayward J.A.,Burnet Institute | Hayward J.A.,Monash University | Tachedjian M.,CSIRO | Cui J.,University of Sydney | And 8 more authors.
Retrovirology | Year: 2013

Background: Betaretroviruses infect a wide range of species including primates, rodents, ruminants, and marsupials. They exist in both endogenous and exogenous forms and are implicated in animal diseases such as lung cancer in sheep, and in human disease, with members of the human endogenous retrovirus-K (HERV-K) group of endogenous betaretroviruses (βERVs) associated with human cancers and autoimmune diseases. To improve our understanding of betaretroviruses in an evolutionarily distinct host species, we characterized βERVs present in the genomes and transcriptomes of mega- and microbats, which are an important reservoir of emerging viruses.Results: A diverse range of full-length βERVs were discovered in mega- and microbat genomes and transcriptomes including the first identified intact endogenous retrovirus in a bat. Our analysis revealed that the genus Betaretrovirus can be divided into eight distinct sub-groups with evidence of cross-species transmission. Betaretroviruses are revealed to be a complex retrovirus group, within which one sub-group has evolved from complex to simple genomic organization through the acquisition of an env gene from the genus Gammaretrovirus. Molecular dating suggests that bats have contended with betaretroviral infections for over 30 million years.Conclusions: Our study reveals that a diverse range of betaretroviruses have circulated in bats for most of their evolutionary history, and cluster with extant betaretroviruses of divergent mammalian lineages suggesting that their distribution may be largely unrestricted by host species barriers. The presence of βERVs with the ability to transcribe active viral elements in a major animal reservoir for viral pathogens has potential implications for public health. © 2013 Hayward et al.; licensee BioMed Central Ltd. Source

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