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Histological image of cerebellum, showing Purkinje cells with eosinophilic intracytoplasmic inclusion bodies (arrows). H&E, scale bar = 50 µm. Courtesy of Dr John Bingham, CSIRO Australian Animal Health Laboratory.
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Case seriesThe first two confirmed cases of Australian bat lyssavirus (ABLV) infection in horses are presented. Both cases occurred in the same week in May 2013 in paddock mates in south-east Queensland. Australia has been one of only a few countries considered free from rabies-like viruses in domestic animal species. ABLV infection had previously...
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Bats are natural reservoirs of the largest proportion of viral zoonoses among mammals, thus understanding the conditions for pathogen persistence in bats is essential to reduce human risk. Focusing on the European Bat Lyssavirus subtype 1 (EBLV-1), causing rabies disease, we develop a data-driven spatially explicit metapopulation model to investiga...
Citations
... Filoviridae families (Ebolavirus and Marburgvirus). 8,9 To date, there have been three confirmed fatal cases [10][11][12] and one suspected ABLV case 13 reported in people and two in horses, 14 all occurring in Queensland. ...
Australian bat lyssavirus (ABLV) is a member of the Lyssavirus genus of the Rhabdoviridae family and is found in Australian bat species. It is of public health concern because of the rabies-like syndrome it causes in humans, resulting in government health and wildlife agencies using varied communication approaches to inform targeted audiences about zoonotic risks associated with handling bats. Despite these warnings, the number of reports of human-bat interactions remains high. This paper details a survey conducted to analyse the approaches utilised by a range of stakeholders to educate and communicate warnings to their target audiences. The survey focused on identifying the target audiences, communication methods used, along with the message frequency, content, and perceived effectiveness. Analysis of the top three messages delivered by stakeholders revealed that over half were information-focused messages and over a third, instruction-focused. Stakeholders identified the need to balance messaging about bat handling risks with information regarding the vulnerable status of bats and their environmental significance. Whilst the most common and (perceived) effective method of communication was one-on-one discussions, it was also identified to be ineffective for targeting mass audiences leading stakeholders to recognise the need to adapt to more efficient means of communication. The outcomes of this study may be useful to improve risk communication strategies regarding ABLV in Australia.
... Due to the vast tropism of RABV and the high serologic similarity between RABV and ABLV, there remains much concern about the potential of ABLV to expand its tropism in the future, comparable to that of its serologic relative. Although ABLV infections have not been observed in any other mammal species to date besides Australian bats, three cases in humans, and two cases in horses, one scientific study suggests that domestic cats and dogs have the potential to become infected with ABLV p and will likely recover instead of succumbing to the disease (Annand and Reid, 2014;McColl et al., 2007). Unfortunately, this study could not address the potential of domestic animals spreading ABLV p to humans or explain why domestic animals were less likely to succumb to the disease. ...
... These studies suggest that ABLV has the potential to expand its tropism across more warm-blooded mammalian species in the future with the right mutations (Weir et al., 2014a). The only recorded spillover event in horses also suggests the potential for ABLV to infect other terrestrial mammals in its future, but researchers have not alluded to which terrestrial animal is most likely to harbor the next spillover event (Annand and Reid, 2014). Understanding the extent of potential ABLV hosts is an area of research that deserves the attention as this knowledge would enhance current and future protocols on how to appropriately and effectively minimize the spread, evolution, and transmission of ABLV. ...
... Horses are not currently considered natural reservoirs of ABLV; instead, horses are simply recognized as susceptible hosts from a single known spillover event. In May 2013, two horses in Queensland, Australia were diagnosed and euthanized from an infection caused by an ABLV s variant (Annand and Reid, 2014;Weir et al., 2014a). The first case involved an 18-month-old female which initially struggled with coordination and movement of her hindlimbs. ...
Australian bat lyssavirus (ABLV) is a negative-sense, single-stranded RNA rhabdovirus capable of causing fatal acute encephalitis in humans with similar pathogenesis to its closest serologic relative, rabies virus (RABV). In this review, we describe emergence and classification of ABLV, its known virology, reservoirs, and hosts, as well as both the pathogenesis and treatment approaches currently employed for presumed infections. ABLV was first identified in New South Wales, Australia in 1996 and emerged in humans months later in Queensland, Australia. Only five known bat reservoirs, all of which fall within the Pteropus and Saccolaimus genera, have been identified to date. Although ABLV antigens have been identified in bats located outside of Australia, the three known human ABLV infections to date have occurred within Australia. As such, there remains a potential for ABLV to expand its presence within and beyond Australia. ABLV infections are currently treated as if they were RABV infections by administering neutralizing antibodies against RABV at the site of the wound and employing the rabies vaccine upon possible exposures. Due to its recent emergence, there is still much left unknown about ABLV, posing concerns with how to safely and effectively address current and future ABLV infections.
... Progressive hindlimb ataxia, photophobia, nictitating membrane protrusion, altered behavior, circling, nystagmus, head pressing, cervical ventroflexion, mydriasis, hypersalivation, dysphagia, and convulsions were reported in horses infected with Australian bat lyssavirus. 35 Negri bodies were identified in Purkinje cells from these horses. 35 ...
... 35 Negri bodies were identified in Purkinje cells from these horses. 35 ...
... 30,31,38 Negri bodies are sharp round to oval eosinophilic inclusions of variable sizes (0.3-20 mm) in the neuronal perikarya and proximal dendrite, mainly found in cerebellar Purkinje cells, brainstem nuclei neurons, and pyramidal cells in the hippocampus (Ammon's horn) but can also be found in the spinal cord. [2][3][4]28,35,39 It is estimated that less than 50% of affected animals have Negri bodies, and their absence does not exclude the diagnosis of rabies. 33,34,39 For this reason, DFA is performed in all suspects (100% sensitivity). ...
Several viruses transmitted by biological vectors or through direct contact, air, or ingestion cause neurologic disease in equids. Of interest are viruses of the Togaviridae, Flaviviridae, Rhabdoviridae, Herpesviridae, Bornaviridae, and Bunyaviridae families. Variable degree of inflammation is present with these viruses but lack of an inflammatory response does not rule out their presence. The goal of this article is to provide an overview on pathophysiologic and clinical aspects of nonarboviral equine encephalitides, specifically on lyssaviruses (rabies) and bornaviruses (Borna disease).
... Additional nucleoprotein (N) gene-specific testing (29) is limited to HeV-positive samples that undergo confirmatory testing (30) or in the minority (<7% nationally) of suspected equine HeV cases submitted directly to the national reference laboratory from states where spillover is considered less likely (25) and state testing is unavailable. This distinction is notable because it means that most horse-disease cases found negative for HeV are not investigated further, despite evidence that other viruses with potential spillover risk to horses, including novel related batborne paramyxoviruses, circulate in Australia (27,(31)(32)(33)(34)(35). Likewise, animal health surveillance worldwide prioritizes targeted testing to exclude pathogens of established importance over open-ended diagnostic approaches, which are inherently more challenging to put in place and interpret. ...
... Additional nucleoprotein (N) gene-specific testing (29) is limited to HeV-positive samples that undergo confirmatory testing (30) or in the minority (<7% nationally) of suspected equine HeV cases submitted directly to the national reference laboratory from states where spillover is considered less likely (25) and state testing is unavailable. This distinction is notable because it means that most horse-disease cases found negative for HeV are not investigated further, despite evidence that other viruses with potential spillover risk to horses, including novel related batborne paramyxoviruses, circulate in Australia (27,(31)(32)(33)(34)(35). Likewise, animal health surveillance worldwide prioritizes targeted testing to exclude pathogens of established importance over open-ended diagnostic approaches, which are inherently more challenging to put in place and interpret. ...
We identified and isolated a novel Hendra virus (HeV) variant not detected by routine testing from a horse in Queensland, Australia, that died from acute illness with signs consistent with HeV infection. Using whole-genome sequencing and phylogenetic analysis, we determined the variant had ≈83% nt identity with prototypic HeV. In silico and in vitro comparisons of the receptor-binding protein with prototypic HeV support that the human monoclonal antibody m102.4 used for postexposure prophylaxis and current equine vaccine will be effective against this variant. An updated quantitative PCR developed for routine surveillance resulted in subsequent case detection. Genetic sequence consistency with virus detected in grey-headed flying foxes suggests the variant circulates at least among this species. Studies are needed to determine infection kinetics, pathogenicity, reservoir-species associations, viral-host coevolution, and spillover dynamics for this virus. Surveillance and biosecurity practices should be updated to acknowledge HeV spillover risk across all regions frequented by flying foxes.
... Two cases of natural ABLV infection in horses have been reported in Queensland. 10,11 Symptoms included progressive hind-limb ataxia, altered demeanour and mild behavioural changes. 10 They deteriorated rapidly after the onset of clinical signs and exhibited dysphagia, lethargy and recumbency. ...
... 10,11 Symptoms included progressive hind-limb ataxia, altered demeanour and mild behavioural changes. 10 They deteriorated rapidly after the onset of clinical signs and exhibited dysphagia, lethargy and recumbency. 10 Both horses developed generalised seizures and were subsequently euthanased. ...
... 10 They deteriorated rapidly after the onset of clinical signs and exhibited dysphagia, lethargy and recumbency. 10 Both horses developed generalised seizures and were subsequently euthanased. 10 The insectivorous variant of ABLV (ABLV-IN) was detected and isolated from both the brain and saliva of the infected horses. ...
Australian Bat lyssaviruses (ABLV) are known to be endemic in bats in New South Wales (NSW), Australia. These viruses pose a public health risk because they cause a fatal disease in humans that is indistinguishable from classical rabies infection. All potentially infectious contact between bats and humans, or between bats and domestic animals, should be investigated to assess the risk of virus transmission by submitting the bat for testing to exclude ABLV infection. The aim of this study was to establish the prevalence of ABLV infection in bats submitted for testing in NSW and to document any trends or changes in submission and bat details. We examined all submissions of samples for ABLV testing received by the NSW Department of Primary Industries Virology Laboratory for the 13-year period between 1 May 2008 and 30 April 2021. Fifty-four (4.9%) ABLV-infected bats were detected, with some clustering of positive results. This is greater than the prevalence estimated from wild-caught bats. All bats should be considered a potential source of ABLV. In particular, flying-foxes with rabies-like clinical signs, and with known or possible human interaction, pose the highest public health risk because they are more likely to return a positive result for ABLV infection. This review of ABLV cases in NSW will help veterinarians to recognise the clinical presentations of ABLV infection in bats and emphasises the importance of adequate rabies vaccination for veterinarians.
... Infected bats may also present with apparent respiratory difficulties [8], or in some cases may appear normal. There have been three cases of ABLV infection in humans in Australia, all with a history of a bite or scratch from a bat [9][10][11][12], and two cases in domestic animals, both horses infected in the same paddock in 2013, probably due to exposure to a single infected bat [13,14]. Transmission to companion animals is considered a potential means by which humans could be exposed to the virus. ...
Australian bat lyssavirus (ABLV) was first described in 1996 and has been regularly detected in Australian bats since that time. While the virus does not cause population level impacts in bats and has minimal impacts on domestic animals, it does pose a public health risk. For this reason, bats are monitored for ABLV and a national dataset is collated and maintained by Wildlife Health Australia. The 2010–2016 dataset was analysed using logistic regression and time-series analysis to identify predictors of infection status in bats and the factors associated with human exposure to bats. In common with previous passive surveillance studies, we found that little red flying-foxes (Pteropus scapulatus) are more likely than other species to be infected with ABLV. In the four Australian mainland species of flying-fox, there are seasonal differences in infection risk that may be associated with reproductive cycles, with summer and autumn the seasons of greatest risk. The risk of human contact was also seasonal, with lower risk in winter. In line with other studies, we found that the circumstances in which the bat is encountered, such as exhibiting abnormal behaviour or being grounded, are risk factors for ABLV infection and human contact and should continue be key components of public health messaging. We also found evidence of biased recording of some types of information, which made interpretation of some findings more challenging. Strengthening of “One Health” linkages between public health and animal health services at the operational level could help overcome these biases in future, and greater harmonisation nationally would increase the value of the dataset.
... 18 On a disease-by-disease and state-by-state basis 'One Health' discussion is carried out between sectors and in many instances has resulted in improvements in zoonotic disease operations. [39][40][41][42] The National Significant Diseases Investigation Program (NSDIP) provides limited funds for registered, nongovernment veterinarians to investigate significant disease events, defined as those exhibiting high morbidity and mortality, rapid spread, effect on public health, trade or production or where initial investigation has failed to establish a diagnosis. 43,44 While NSDIP is not intended to support the investigation of established notifiable diseases such as HeV in horses, it does include clinically similar diseases or diseases showing increasing incidence or an expanding geographic or host range. ...
Background
Hendra virus (HeV) is endemic in Australian flying foxes, posing a threat to equine and human health. Equine vaccination remains the most effective risk mitigation strategy. Many horses remain unvaccinated – even in higher‐risk regions. Debate surrounding the vaccine's use is characterised by conflicting perspectives, misunderstanding and mistrust. Private veterinary practitioners are critical to early identification of public health risk through recognition, sampling and management of suspect‐equine‐HeV‐cases. However, managing such cases can be burdensome, with some veterinarians opting not to attend unvaccinated horses or to abandon equine practice because of risk posed by HeV disease and liability.
Objective
Ascertain the perspectives of informed citizens on what obligations (if any) private veterinarians have to attend unvaccinated horses with HeV or HeV‐like disease.
Methods
Three citizens' juries were tasked with considering approaches to managing HeV risk in Australia, including (reported here) roles and obligations of private veterinarians in responding to HeV‐suspect‐cases.
Results
Jurors acknowledged that HeV management posed an important challenge for private veterinarians. A clear majority (27 of 31 jurors) voted that veterinarians should not be obliged to attend unvaccinated horses. All recognised that greater support for veterinarians should be a priority.
Conclusions
When informed of HeV risks and strategies for control and management, citizens appreciated the need to support veterinarians performing this critical ‘One Health’ role for public benefit. The current governance framework within which zoonotic disease recognition and response operates limits the contingency and scope for increasing support and efficacy of these important veterinary public health practices.
... ABLV is transmitted to humans from bats, resulting in a serious and fatal form of rabies that mirrors encephalitic rabies caused by RABV infection (Allworth et al., 1996;Francis et al., 2014;Hanna et al., 2000). Also, several cases of fatal ABLV infection have been reported in horses, demonstrating the additional risk of ABLV transmission to domesticated animals, with possible subsequent infection of their handlers (Annand and Reid, 2014;Field, 2018;Shinwari et al., 2014;Si et al., 2016). ...
Traditional mouse models of lyssavirus pathogenesis rely on euthanizing large groups of animals at various time points post-infection, processing infected tissues, and performing histological and molecular analyses to determine anatomical sites of infection. While powerful by some measures, this approach is limited by the inability to monitor disease progression in the same mice over time. In this study, we established a novel non-invasive mouse model of lyssavirus pathogenesis, which consists of longitudinal imaging of a luciferase-expressing Australian bat lyssavirus (ABLV) reporter virus. In vivo bioluminescence imaging (BLI) in mice revealed viral spread from a peripheral site of inoculation into the central nervous system (CNS), with kinetically and spatially distinct foci of replication in the footpad, spinal cord, and hindbrain. Detection of virus within the CNS was associated with onset of clinical disease. Quantification of virus-derived luminescent signal in the brain was found to be a reliable measure of viral replication, when compared to traditional molecular methods. Furthermore, we demonstrate that in vivo imaging of ABLV infection is not restricted to the use of albino strains of mice, but rather strong BLI signal output can be achieved by shaving the hair from the heads and spines of pigmented strains, such as C57BL/6. Overall, our data show that in vivo BLI can be used to rapidly and non-invasively identify sites of lyssavirus replication and to semi-quantitatively determine viral load without the need to sacrifice mice at multiple time points.
... Given public health interventions that focus solely on disease prevention in humans have no effect on the reduction of infec- Dog-mediated rabies and the regional situation Dog-mediated rabies is the cause of ninety-nine percent of the 59 000 human rabies deaths annually with the greatest burden being in India and across Africa 6 . Australia has been free of the dog rabies virus variant, although Australian Bat Lyssavirus is maintained in native bats, and has spilled over to horses and people [7][8][9] . Travellers to endemic dog-mediated rabies countries should consider the risk of being exposed to the deadly virus and if necessary seek medical advice about pre-exposure prophylaxis rabies vaccination 10,11 . ...
It is unacceptable that as we advance into the 21st century rabies is still a threat to humans and animals alike. Given public health interventions that focus solely on disease prevention in humans have no effect on the reduction of infection in the reservoir hosts, the most effective way to combat human rabies infection is to control the disease transmission by mass vaccination of the animal source, e.g. dogs and wildlife1. This short communication focuses on the global strategic target to end human deaths from dog-mediated rabies by 20302 in line with the Sustainable Development Goals by providing recent updates on World Health Organization (WHO) and OIE guidelines3–5 and recommendations as well as highlighting Australian rabies research activities to prevent an incursion of rabies into the country.
