Spatiotemporal Aspects of Hendra Virus Infection in Pteropid Bats (Flying-Foxes) in Eastern Australia

Fruit bats (Pteropodidae) have received increased attention after the recent emergence of notable viral pathogens of bat origin. Their vagility hinders data collection on abundance and distribution, which constrains modeling efforts and our understanding of bat ecology, viral dynamics, and spillover. We addressed this knowledge gap with models and data on the occurrence and abundance of nectarivorous fruit bat populations at 3 day roosts in southeast Queensland. We used environmental drivers of nectar production as predictors and explored relationships between bat abundance and virus spillover. Specifically, we developed several novel modeling tools motivated by complexities of fruit bat foraging ecology, including: (1) a dataset of spatial variables comprising Eucalypt‐focused vegetation indices, cumulative precipitation, and temperature anomaly; (2) an algorithm that associated bat population response with spatial covariates in a spatially and temporally relevant way given our current understanding of bat foraging behavior; and (3) a thorough statistical learning approach to finding optimal covariate combinations. We identified covariates that classify fruit bat occupancy at each of our three study roosts with 86–93% accuracy. Negative binomial models explained 43–53% of the variation in observed abundance across roosts. Our models suggest that spatiotemporal heterogeneity in Eucalypt‐based food resources could drive at least 50% of bat population behavior at the landscape scale. We found that 13 spillover events were observed within the foraging range of our study roosts, and they occurred during times when models predicted low population abundance. Our results suggest that, in southeast Queensland, spillover may not be driven by large aggregations of fruit bats attracted by nectar‐based resources, but rather by behavior of smaller resident subpopulations. Our models and data integrated remote sensing and statistical learning to make inferences on bat ecology and disease dynamics. This work provides a foundation for further studies on landscape‐scale population movement and spatiotemporal disease dynamics.

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“…; Field et al. , ) and modeling studies of virus survival under different environmental conditions (Martin et al. ).…”

Section: Introductionmentioning

confidence: 99%

Models of Eucalypt phenology predict bat population flux

Giles

Plowright

Eby

et al. 2016

Ecology and Evolution

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“…However, high mortality rates and rapid progression to death in flying‐foxes exposed to the neurotoxin‐producing I. holocyclus (Buettner et al., ) make this putative transmission model improbable. Further, the spatiotemporal pattern of HeV infection in flying‐foxes (Field et al., ) is inconsistent with the I. holocyclus hypothesis, with infection prevalence not reflecting tick abundance.…”

Section: Introductionmentioning

confidence: 99%

“…The spillover of Hendra virus (HeV) into horses, and subsequent transmission to humans, has resulted in fatal respiratory and neurological disease (Field et al., ; Playford et al., ). Australian flying‐foxes of the genus Pteropus are considered to be the reservoir host of HeV (Halpin et al., ; Field et al., ), with recent research demonstrating that Pteropus alecto and Pteropus conspicillatus are the predominant hosts of this virus (Smith et al., ; Edson et al., ; Goldspink et al., ). The most parsimonious hypotheses on the mode of HeV transmission, both between flying‐foxes, and from flying‐foxes to horses, propose direct or indirect contact with infected urine (Field et al., , ; Smith et al., ; Edson et al., ), although neither transmission cycle has been conclusively demonstrated.…”

Section: Introductionmentioning

confidence: 99%

No Evidence of Hendra Virus Infection in the Australian Flying‐fox Ectoparasite Genus Cyclopodia

Vidgen

Edson

Hurk

et al. 2016

Zoonoses and Public Health

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Hendra virus (HeV) causes potentially fatal respiratory and/or neurological disease in both horses and humans. Although Australian flying-foxes of the genus Pteropus have been identified as reservoir hosts, the precise mechanism of HeV transmission has yet to be elucidated. To date, there has been limited investigation into the role of haematophagous insects as vectors of HeV. This mode of transmission is particularly relevant because Australian flying-foxes host the bat-specific blood-feeding ectoparasites of the genus Cyclopodia (Diptera: Nycteribiidae), also known as bat flies. Using molecular detection methods, we screened for HeV RNA in 183 bat flies collected from flying-foxes inhabiting a roost in Boonah, Queensland, Australia. It was subsequently demonstrated that during the study period, Pteropus alecto in this roost had a HeV RNA prevalence between 2 and 15% (95% CI [1, 6] to [8, 26], respectively). We found no evidence of HeV in any bat flies tested, including 10 bat flies collected from P. alecto in which we detected HeV RNA. Our negative findings are consistent with previous findings and provide additional evidence that bat flies do not play a primary role in HeV transmission.

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“…and Spectacled (P. conspicillatus) flying-foxes are primary reservoir hosts for Hendra virus (Smith et al 2014;Edson et al 2015 b ;Goldspink et al 2015;Field et al 2015).…”

Section: Introductionmentioning

confidence: 99%

“…Of the four Pteropus species endemic to mainland Australia, there is accumulating evidence that the Black flying-fox (Pteropus alecto), and the paraphyletic Spectacled flying-fox (P. conspicillatus) (Almeida et al 2014), are primary reservoir hosts of Hendra virus (Smith et al 2014;Edson et al 2015 b ;Goldspink et al 2015;Field et al 2015).…”

Section: Introductionmentioning

confidence: 99%

Physiological biomarkers of Hendra virus infection in Australian Flying-foxes (Pteropus spp.)

McMichael¹

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Since 1994 when the disease was first described, there have been over 50 Hendra virus incidents involving more than 90 confirmed or possible equine cases, and 7 associated human cases, with case fatality rates approaching 90% and 60%respectively. Epidemiological studies suggest that flying-foxes, in particular the Black flying-fox (Pteropus alecto) and the closely related Spectacled flying-fox (P.conspicillatus) are the primary natural reservoir hosts. This research project investigates a hypothesised causal association between ecological and/or physiological stress and Hendra virus infection in Pteropus species.During a 12-month study of flying-foxes in Southeast Queensland (SEQ), samples were collected from 446 captured wild P. alecto for analysis of 18 hematologic, 22 biochemical and 8 urinary biomarkers, establishing normal reference ranges and temporal changes for this suite of biomarkers. The population demonstrated statistically significant temporal variation in some biomarkers consistent with life cycle events. In Hendra virus RNA-positive animals all biomarker mean values were within established normal ranges, but some were significantly different compared to Hendra virus RNA-negative animals, notably, increased lymphocyte percent, decreased neutrophil percent, decreased plasma triglyceride levels, increased plasma alkaline phosphatase levels and increased urinary protein levels. The study demonstrated that Hendra virus infection in P. alecto was sub-clinical, and that there was no apparent relationship with nutritional stress, reproductive stress or extreme metabolic demand, which would have caused substantial changes to biomarker values. The relationship between increased urinary protein levels, decreased triglyceride levels and Hendra virus infection is of interest, and may support the premise of urinary tract association and physiological demand with Hendra virus infection of P. alecto.In a second study, a method of collection and assay of urinary cortisol to measure physiological stress in roosting flying-foxes was validated. Differences between the four mainland flying-fox species (P. alecto, P. poliocephalus, P. scapulatus, P. conspicillatus) were established through collection of urine samples from a wide geographic range throughout Queensland and New South Wales from single species roosts. Then, over a three-year study, population urinary cortisol and Hendra virus 3 urinary excretion prevalence was measured from a total of 2208 pooled urine samples from mixed species roosts of flying-foxes from two geographically distinct regions, subtropical SEQ and tropical Far North Queensland (FNQ). An autumn elevation in urinary cortisol in the FNQ population was detected, but no significant seasonal fluctuations in Hendra virus excretion prevalence were found. Urinary cortisol was significantly elevated in both autumn and winter in the SEQ population, the latter temporally associated with a significant winter elevation in Hendra virus excretion prevalence. There was also a strong correlation betwe...

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Spatiotemporal Aspects of Hendra Virus Infection in Pteropid Bats (Flying-Foxes) in Eastern Australia

Cited by 77 publications

References 38 publications

Models of Eucalypt phenology predict bat population flux

Models of Eucalypt phenology predict bat population flux

No Evidence of Hendra Virus Infection in the Australian Flying‐fox Ectoparasite Genus Cyclopodia

Physiological biomarkers of Hendra virus infection in Australian Flying-foxes (Pteropus spp.)

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