Hendra virus survival does not explain spillover patterns and implicates relatively direct transmission routes from flying foxes to horses

Martín, Gerardo; Plowright, Raina K.; Chen, Carla; Kault, David; Selleck, Paul; Skerratt, Lee F.

doi:10.1099/vir.0.000073

Cited by 35 publications

(52 citation statements)

References 33 publications

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“…Its reservoir hosts are the four mainland Australian flying fox fruit bats (Chyroptera:Pteropodidae: Pteropus ), although Pteropus alecto and P. conspicillatus seem to be the most important reservoirs [9–11] ■ ■ . Transmission from flying foxes to horses is thought to occur after ingestion of urine contaminated feed.…”

Section: Introductionmentioning

confidence: 99%

“…This hypothesis has been considered plausible given the ability of HeV to survive for up to 4 days in fruit juice and urine in laboratory conditions at 22 and 37 °C, although HeV is extremely sensitive to desiccation at these temperatures [12] ■ ■ . Even under the best virus survival scenario represented by air temperatures, spillover has not occurred in areas with the highest possible survival during certain seasons [11] ■ . This suggests that survival as explained by air temperature is not important for spillover, and transmission is likely to be relatively direct.…”

Section: Introductionmentioning

confidence: 99%

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Microclimates Might Limit Indirect Spillover of the Bat Borne Zoonotic Hendra Virus

et al. 2017

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Infectious diseases are transmitted when susceptible hosts are exposed to pathogen particles that can replicate within them. Among factors that limit transmission, the environment is particularly important for indirectly transmitted parasites. To try and assess a pathogens’ ability to be transmitted through the environment and mitigate risk we need to quantify its decay where transmission occurs in space such as the microclimate harbouring the pathogen. Hendra virus, a Henipavirus from Australian Pteropid bats spills-over to horses and humans, causing high mortality. While a vaccine is available, its limited uptake has reduced opportunities for adequate risk management to humans, hence the need to develop synergistic preventive measures, like disrupting its transmission pathways. Transmission likely occurs shortly after virus excretion in paddocks, however no survival estimates to-date have used real environmental conditions. Here we recorded microclimate conditions and fitted models that predict temperatures and potential evaporation, which we used to simulate virus survival with a temperature-survival model and modification based on evaporation. Predicted survival was lower than previously estimated and likely to be even lower according to potential evaporation. Our results indicate that transmission should occur shorlty after the virus is excreted, in a relatively direct way. When potential evaporation is low, and survival is more similar to temperature dependent estimates, transmission might be indirect because the virus can wait several hours until contact is made. We recommend restricting horses’ access to trees during night time and reducing grass under trees to reduce virus survival.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Microclimates Might Limit Indirect Spillover of the Bat Borne Zoonotic Hendra Virus

et al. 2017

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“…Martin G, Plowright R, Chen C, Kault D, Selleck P, et al (2015) Hendra virus survival does not explain spillover patterns and implicates relatively direct transmission routes from flying foxes to horses.…”

Section: Referencesmentioning

confidence: 99%

“…Thus our original conservative interpretation of the effect of environmental temperature on Hendra virus survival is valid. Martin et al (2015) incorrectly claim that we 'state that HeV survival is a major driver of transmission and seasonality'. To the contrary, we state that 'While temperature is an important factor in virus survival, additional factors contribute to a complex causality and effective transmission.'…”

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The Effect of Environmental Temperature on Hendra Virus Survival

Scanlan¹,

Kung²,

Selleck

et al. 2015

EcoHealth

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In their recent paper, Martin et al. (2015) use an alternative modelling approach to re-test our hypothesis of the effect of environmental temperature on Hendra virus survival (Scanlan et al. 2014). They identify a translation error in the calculated half-life of virus at 56°C, the highest data point on the regression curve that formed the basis of our model. We have re-run the model with the corrected value (1.8 min). While the error is regrettable, it has no practical effect on the estimation of virus survival at the six locations used in the model, because the mean maximum temperature did not exceed 33°C at any location in any month, well below the next highest data point (37°C) on the curve. Hourly temperatures used in other simulations exceeded 37°C on just eight occasions-0.06 % of total hours, and less than 0.5 % of hours in the hottest month in the hottest location. Thus our original conservative interpretation of the effect of environmental temperature on Hendra virus survival is valid. Martin et al. (2015) incorrectly claim that we 'state that HeV survival is a major driver of transmission and seasonality'. To the contrary, we state that 'While temperature is an important factor in virus survival, additional factors contribute to a complex causality and effective transmission.' We have linked a detailed erratum to our original publication. REFERENCESMartin G, Plowright R, Chen C, Kault D, Selleck P, et al. (2015) Hendra virus survival does not explain spillover patterns and implicates relatively direct transmission routes from flying foxes to horses.

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Models of Eucalypt phenology predict bat population flux

Giles

Plowright

Eby

et al. 2016

Ecology and Evolution

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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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Hendra virus survival does not explain spillover patterns and implicates relatively direct transmission routes from flying foxes to horses

Cited by 35 publications

References 33 publications

Microclimates Might Limit Indirect Spillover of the Bat Borne Zoonotic Hendra Virus

Microclimates Might Limit Indirect Spillover of the Bat Borne Zoonotic Hendra Virus

The Effect of Environmental Temperature on Hendra Virus Survival

Models of Eucalypt phenology predict bat population flux

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