Hendra Virus Protection Adopted by Equine Veterinarians

Hendra Virus Protection Adopted by Equine Veterinarians

Protective equipment use and disease awareness likely reduced human infections during recent outbreaks.

A marked increase in the incidence of hendra virus cases (termed "spillover events") in horses over the last 18 months has again brought this disease to prominence in Australia.

The virus was first recognized in 1994 following the death of a popular horse trainer and 20 horses in Hendra, a suburb of Brisbane, Queensland, Australia. A member of the Paramyxoviridae, hendra virus has been categorized in the henipah virus genus due to its similarity to nipah virus, another lethal, bat-borne zoonotic agent.

Between the 1994 outbreak and June 2011, 14 hendra virus spillover events had been confirmed that resulted in seven human infections (four fatal, including two veterinarians). The publicity following these events resulted in widespread testing of suspect or ill horses and more stringent use of personal protective equipment (PPE). Since June 2011, at least 25 outbreaks have occurred, nearly double the total number of cases prior to then. A welcome difference in the recent spate of hendra cases is that no human infections have resulted from personnel handling or treating infected horses. Extensive testing of in-contact humans by health authorities is routine following every confirmed equine hendra case. Both heightened awareness of veterinarians and horse owners, together with a greater acceptance of PPE practices are considered to be largely responsible for the lack of human infections during the recent cases.

Equipment now in use by eastern Australian equine practitioners includes: disposable splashproof overalls, disposable respirators (N95 rated), safety eyewear or full-face shield, rubber boots or disposable shoe covers, and disposable gloves (often used in duplicate or triplicate). Pre-packaged PPE kits are now widely available. Following intensive lobbying by veterinary associations, costs for these items and other biohazard equipment are subsidized for Queensland practitioners dealing with suspect cases.

In addition to these measures, the Australian Veterinary Association and Veterinary Licensing Boards have insisted that all veterinary students be certified in PPE application and be aware of basic facts regarding hendra virus infection prior to observing equine veterinary practice. Although hendra virus in horses was originally restricted to the northeastern seaboard of Queensland and northern New South Wales, recent outbreaks have extended farther to the south and east.

The natural hosts of hendra virus are bats (flying foxes) that most likely shed virus through urine, feces, and other bodily fluids. Areas beneath fruiting trees such as fig trees are considered particularly high risk for horses as this is where bats tend to congregate. Human infection results from close contact with the body fluids and tissues of infected or dead horses.

Although Hendra virus has instilled fear in the Australian horse community, there have been some recent developments: a vaccine for horses has been fast-tracked for release in 2013, and a stall-side rapid diagnostic test is also under development.

Australian equine veterinarians remain grateful to researchers at the Commonwealth Scientific and Industrial Research Organization's Australian Animal Health Laboratory in Geelong, Victoria, who have played a major role in these developments and basic hendra virus research. The Queensland Department of Primary Industries and the Australian Biosecurity CRC for Emerging Infectious Disease also are acknowledged for their efforts.

CONTACT: Charles El-Hage, BVSc, MACVSc--cmeh@unimelb.edu.au--The University of Melbourne Faculty of Veterinary Science, Equine Centre--Werribee, Victoria, Australia
Brett Tennent-Brown, BVSc, MS, Dipl. ACVIM, ACVECC, provided assistance with this article.

This is an excerpt from Equine Disease Quarterly, funded by underwriters at Lloyd's, London, brokers, and their Kentucky agents.


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