title: Routes of Hendra Virus Excretion in Naturally-Infected Flying-Foxes: Implications for Viral Transmission and Spillover Risk.
abstract: Pteropid bats or flying-foxes (Chiroptera: Pteropodidae) are the natural host of Hendra virus (HeV) which sporadically causes fatal disease in horses and humans in eastern Australia. While there is strong evidence that urine is an important infectious medium that likely drives bat to bat transmission and bat to horse transmission, there is uncertainty about the relative importance of alternative routes of excretion such as nasal and oral secretions, and faeces. Identifying the potential routes of HeV excretion in flying-foxes is important to effectively mitigate equine exposure risk at the bat-horse interface, and in determining transmission rates in host-pathogen models. The aim of this study was to identify the major routes of HeV excretion in naturally infected flying-foxes, and secondarily, to identify between-species variation in excretion prevalence. A total of 2840 flying-foxes from three of the four Australian mainland species (Pteropus alecto, P. poliocephalus and P. scapulatus) were captured and sampled at multiple roost locations in the eastern states of Queensland and New South Wales between 2012 and 2014. A range of biological samples (urine and serum, and urogenital, nasal, oral and rectal swabs) were collected from anaesthetized bats, and tested for HeV RNA using a qRT-PCR assay targeting the M gene. Forty-two P. alecto (n = 1410) had HeV RNA detected in at least one sample, and yielded a total of 78 positive samples, at an overall detection rate of 1.76% across all samples tested in this species (78/4436). The rate of detection, and the amount of viral RNA, was highest in urine samples (>serum, packed haemocytes >faecal >nasal >oral), identifying urine as the most plausible source of infection for flying-foxes and for horses. Detection in a urine sample was more efficient than detection in urogenital swabs, identifying the former as the preferred diagnostic sample. The detection of HeV RNA in serum is consistent with haematogenous spread, and with hypothesised latency and recrudesence in flying-foxes. There were no detections in P. poliocephalus (n = 1168 animals; n = 2958 samples) or P. scapulatus (n = 262 animals; n = 985 samples), suggesting (consistent with other recent studies) that these species are epidemiologically less important than P. alecto in HeV infection dynamics. The study is unprecedented in terms of the individual animal approach, the large sample size, and the use of a molecular assay to directly determine infection status. These features provide a high level of confidence in the veracity of our findings, and a sound basis from which to more precisely target equine risk mitigation strategies.
authors.affiliation: Queensland Centre for Emerging Infectious Diseases, Department of Agriculture and Fisheries, Coopers Plains, Queensland, Australia.
authors.forename: Daniel
authors.initials: D
authors.lastname: Edson
authors.affiliation: Queensland Centre for Emerging Infectious Diseases, Department of Agriculture and Fisheries, Coopers Plains, Queensland, Australia; EcoHealth Alliance, New York, New York, United States of America.
authors.forename: Hume
authors.initials: H
authors.lastname: Field
authors.affiliation: Queensland Centre for Emerging Infectious Diseases, Department of Agriculture and Fisheries, Coopers Plains, Queensland, Australia.
authors.forename: Lee
authors.initials: L
authors.lastname: McMichael
authors.affiliation: Queensland Centre for Emerging Infectious Diseases, Department of Agriculture and Fisheries, Coopers Plains, Queensland, Australia.
authors.forename: Miranda
authors.initials: M
authors.lastname: Vidgen
authors.affiliation: Queensland Centre for Emerging Infectious Diseases, Department of Agriculture and Fisheries, Coopers Plains, Queensland, Australia.
authors.forename: Lauren
authors.initials: L
authors.lastname: Goldspink
authors.affiliation: Queensland Centre for Emerging Infectious Diseases, Department of Agriculture and Fisheries, Coopers Plains, Queensland, Australia.
authors.forename: Alice
authors.initials: A
authors.lastname: Broos
authors.affiliation: Queensland Centre for Emerging Infectious Diseases, Department of Agriculture and Fisheries, Coopers Plains, Queensland, Australia.
authors.forename: Deb
authors.initials: D
authors.lastname: Melville
authors.affiliation: Queensland Centre for Emerging Infectious Diseases, Department of Agriculture and Fisheries, Coopers Plains, Queensland, Australia.
authors.forename: Joanna
authors.initials: J
authors.lastname: Kristoffersen
authors.affiliation: Queensland Centre for Emerging Infectious Diseases, Department of Agriculture and Fisheries, Coopers Plains, Queensland, Australia.
authors.forename: Carol
authors.initials: C
authors.lastname: de Jong
authors.affiliation: Queensland Centre for Emerging Infectious Diseases, Department of Agriculture and Fisheries, Coopers Plains, Queensland, Australia.
authors.forename: Amanda
authors.initials: A
authors.lastname: McLaughlin
authors.affiliation: Elizabeth Macarthur Agricultural Institute, New South Wales Department of Primary Industries, Menangle, NSW, Australia.
authors.forename: Rodney
authors.initials: R
authors.lastname: Davis
authors.affiliation: Queensland Centre for Emerging Infectious Diseases, Department of Agriculture and Fisheries, Coopers Plains, Queensland, Australia.
authors.forename: Nina
authors.initials: N
authors.lastname: Kung
authors.affiliation: Wollongbar Primary Industries Institute, New South Wales Department of Primary Industries, Wollongbar, NSW, Australia.
authors.forename: David
authors.initials: D
authors.lastname: Jordan
authors.affiliation: Elizabeth Macarthur Agricultural Institute, New South Wales Department of Primary Industries, Menangle, NSW, Australia.
authors.forename: Peter
authors.initials: P
authors.lastname: Kirkland
authors.affiliation: Queensland Centre for Emerging Infectious Diseases, Department of Agriculture and Fisheries, Coopers Plains, Queensland, Australia.
authors.forename: Craig
authors.initials: C
authors.lastname: Smith
mesh_terms: D000818:Animals; D001315:Australia; D002685:Chiroptera / Q000145:classification / Q000821:virology*; D005243:Feces / Q000821:virology; D005260:Female; D045404:Hendra Virus / Q000235:genetics / Q000302:isolation & purification*; D045464:Henipavirus Infections / Q000635:transmission / Q000662:veterinary* / Q000821:virology*; D006734:Horse Diseases / Q000821:virology; D006736:Horses; D008297:Male; D009055:Mouth / Q000821:virology; D009666:Nose / Q000821:virology; D012007:Rectum / Q000821:virology; D044967:Serum / Q000821:virology; D013045:Species Specificity; D014556:Urine / Q000821:virology*