Natural Hendra Virus Infection in Flying-Foxes - Tissue Tropism and Risk Factors

Abstract

Hendra virus (HeV) is a lethal zoonotic agent that emerged in 1994 in Australia. Pteropid bats (flying-foxes) are the natural reservoir. To date, HeV has spilled over from flying-foxes to horses on 51 known occasions, and from infected horses to close-contact humans on seven occasions. We undertook screening of archived bat tissues for HeV by reverse transcription quantitative polymerase chain reaction (RT-qPCR). Tissues were tested from 310 bats including 295 Pteropodiformes and 15 Vespertilioniformes. HeV was detected in 20 individual flying-foxes (6.4%) from various tissues including spleen, kidney, liver, lung, placenta and blood components. Detection was significantly higher in Pteropus Alecto and P. conspicillatus, identifying species as a risk factor for infection. Further, our findings indicate that HeV has a predilection for the spleen, suggesting this organ plays an important role in HeV infection. The lack of detections in the foetal tissues of HeV-positive females suggests that vertical transmission is not a regular mode of transmission in naturally infected flying-foxes, and that placental and foetal tissues are not a major source of infection for horses. A better understanding of HeV tissue tropism will strengthen management of the risk of spillover from flying-foxes to horses and ultimately humans.

Models of Eucalypt phenology predict bat population flux

“…; Goldspink et al. ). Spatial distribution and behavior can be highly variable across species and individuals, ranging from sedentary to entirely migratory behavior (Eby ; Smith et al.…”

Landscape Utilisation, Animal Behaviour and Hendra Virus Risk

“…Yet equine cases are infrequent despite the estimated hundreds of thousands of horses that geographically overlap the distribution of flying-foxes. While this may be explained by the evident low excretion prevalence in flyingfoxes Goldspink et al 2015;Edson et al, in preparation) and differential excretion in different species (Smith et al 2014;Edson et al, in preparation), it may also indicate that key factors required for effective transmission also occur infrequently. In this paper, we suggest equine landscape utilisation as plausibly compounding exposure risk.…”

“…In August and September 2011, we used mist-nets (18 m wide and 4 m deep) hoist between two 12 m aluminium masts to capture black flying-foxes at dusk or dawn as they, respectively, left or returned to the roost (de Jong et al 2005;Epstein and Field 2011). Our focus on black flying-foxes reflected increasing evidence that this species is an epidemiologically important in HeV transmission (Smith et al 2014;Goldspink et al 2015). The study period overlapped the second half of the May-October gestation period in this species.…”

Application of a quantitative entry assessment model to compare the relative risk of incursion of zoonotic bat-borne viruses into European Union Member States

“…There was an initial coincidence of HeV outbreaks with birthing seasons of Australian fruit bat species and the isolation of HeV from the uterine fluid and aborted foetus of a P. poliocephalus bat indicated that this may be a significant route of infection for horses (Fogarty et al, 2008). However, there now appears to be a temporal clustering of spillovers during the winter Microbial Risk Analysis 7 (2017) 8-28 period with 35/51 spillovers to June 2014 occurring in June, July and August (Goldspink et al, 2015). The proportion of the year that bats are assumed to shed active virus is therefore estimated to be ∼4 months or 0.33 of 1 year.…”