title: Flying-fox species density--a spatial risk factor for Hendra virus infection in horses in eastern Australia.
abstract: Hendra virus causes sporadic but typically fatal infection in horses and humans in eastern Australia. Fruit-bats of the genus Pteropus (commonly known as flying-foxes) are the natural host of the virus, and the putative source of infection in horses; infected horses are the source of human infection. Effective treatment is lacking in both horses and humans, and notwithstanding the recent availability of a vaccine for horses, exposure risk mitigation remains an important infection control strategy. This study sought to inform risk mitigation by identifying spatial and environmental risk factors for equine infection using multiple analytical approaches to investigate the relationship between plausible variables and reported Hendra virus infection in horses. Spatial autocorrelation (Global Moran's I) showed significant clustering of equine cases at a distance of 40 km, a distance consistent with the foraging 'footprint' of a flying-fox roost, suggesting the latter as a biologically plausible basis for the clustering. Getis-Ord Gi* analysis identified multiple equine infection hot spots along the eastern Australia coast from far north Queensland to central New South Wales, with the largest extending for nearly 300 km from southern Queensland to northern New South Wales. Geographically weighted regression (GWR) showed the density of P. alecto and P. conspicillatus to have the strongest positive correlation with equine case locations, suggesting these species are more likely a source of infection of Hendra virus for horses than P. poliocephalus or P. scapulatus. The density of horses, climate variables and vegetation variables were not found to be a significant risk factors, but the residuals from the GWR suggest that additional unidentified risk factors exist at the property level. Further investigations and comparisons between case and control properties are needed to identify these local risk factors.
authors.affiliation: Queensland Centre for Emerging Infectious Diseases, Department of Agriculture, Fisheries and Forestry, Brisbane, Queensland, Australia.
authors.forename: Craig
authors.initials: C
authors.lastname: Smith
authors.affiliation: Biosecurity Intelligence Unit, Department of Agriculture, Fisheries and Forestry, Brisbane, Queensland, Australia; GIS People Pty Ltd, Brisbane, Queensland, Australia.
authors.forename: Chris
authors.initials: C
authors.lastname: Skelly
authors.affiliation: Queensland Centre for Emerging Infectious Diseases, Department of Agriculture, Fisheries and Forestry, Brisbane, Queensland, Australia.
authors.forename: Nina
authors.initials: N
authors.lastname: Kung
authors.affiliation: Griffith School of Environment, Griffith University, Brisbane, Queensland, Australia.
authors.forename: Billie
authors.initials: B
authors.lastname: Roberts
authors.affiliation: Queensland Centre for Emerging Infectious Diseases, Department of Agriculture, Fisheries and Forestry, Brisbane, Queensland, Australia; EcoHealth Alliance, New York, New York, United States of America.
authors.forename: Hume
authors.initials: H
authors.lastname: Field
mesh_terms: D000818:Animals; D002685:Chiroptera / Q000821:virology*; D004197:Disease Reservoirs / Q000821:virology; D045404:Hendra Virus; D045464:Henipavirus Infections / Q000453:epidemiology / Q000635:transmission / Q000662:veterinary*; D006734:Horse Diseases / Q000453:epidemiology / Q000635:transmission / Q000821:virology*; D006736:Horses; D009517:New South Wales / Q000453:epidemiology; D011793:Queensland / Q000453:epidemiology; D012307:Risk Factors