Procedures

Hendra Virus Vaccine Implementation - Procedures

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1. Purpose and Objectives

This document outlines procedures for the implementation and appropriate administration of the Hendra Virus (HeV) vaccine (Equivac HeV vaccine).

2. Definitions, Terms, Acronyms

Hendra Virus - a viral disease, carried by flying-foxes or bats, that may infect horses

HeV - Hendra Virus

IBC - Institutional Biosafety Committee, a committee that is established by an Accredited Organisation, as required by the Office of the Gene Technology Regulator

OHS - Occupational Health and Safety

SAFS - School of Agriculture and Food Sciences

SVS - School of Veterinary Sciences

UQ-VMC - UQ Veterinary Medical Centre

3. Procedure Scope/Coverage

These procedures apply to persons involved in activities involving horses or horse tissue at UQ premises. Activities and research involving horses for The University of Queensland are primarily concentrated at the Gatton Campus and Pinjarra Hills site, and as such this paper is directed at those sites and activities. It should be noted that the information contained herein may be applied to other sites and situations.

4. Procedure Statement

These procedures will assist staff, students, researchers and visitors who are involved in activities with horses or horse tissue at UQ premises, or conducting work on UQ-owned horses that may be exposed to Hendra Virus.

5. Risk at UQ

The University of Queensland has, where appropriate, considered the risk of Hendra virus and has acted accordingly. Two detailed audits were conducted in 2011, one each at the Gatton Campus and Pinjarra Hills sites. The Queensland Department of Agriculture and Fisheries have conducted a site visit and issued UQ with further advice. The UQ Institutional Biosafety Committee has considered all relevant hazards and advice.

6. An Overview of the Hendra Virus

Hendra virus (HeV, previously known as Equine morbillivirus) is a Henipavirus related to Nipah virus, both of which are harboured by the Pteropid fruit bat (flying foxes) (Sawatsky et al. 2008, Wang et al. 2001). HeV is a zoonotic pathogen that can be transferred from animals to humans and in this case from horses to humans. HeV was first identified in Brisbane in September 1994 where it caused the death of 14 horses and a trainer. It was subsequently determined that the first spill-over occurred in August 1994 in Mackay, Queensland where infection resulted in the death of two horses and one person.

As of 25 January 2016, a total of 49 confirmed HeV incidents have occurred four of which have involved humans (Queensland Government Hendra Virus Incident Summary) . During this time a total 71 horses have died from HeV infection including those that had to be euthanased. Seven persons have been infected and four have died as a result of HeV (August 2004, September 2004, July 2008 and August 2009) giving an overall mortality rate of approximately 50% in humans.

General information on Hendra Virus can be accessed via the Queensland Government Department of Agriculture and Fisheries.

This information highlights the following:

  • Flying foxes are the natural hosts for Hendra virus. The virus can spread from flying foxes to horses and, very rarely, from horses to humans.
  • There is no evidence of human-to-human, human-to-horse or bat-to-human spread of Hendra virus.
  • Humans have become infected from handling infected horses (both before and after they develop clinical signs, as well as during autopsies).
  • Hendra virus is a notifiable disease and all suspected cases in horses must be reported to the Queensland Department of Agriculture and Fisheries.
  • Epidemiological information about HeV is incomplete and remains the subject of ongoing research.
  • The known detections have occurred on or east of the Great Dividing Range from Cairns to Northern New South Wales, but this cannot be assumed to be the extent of the range of HeV, as there remains a potential for HeV in horses wherever flying foxes are found.
  • As horses are routinely transported over long distances, they could be moved within the recognised HeV incubation period from an area where they may have been in contact with flying foxes to an area where flying foxes do not exist.

Furthermore:

  • Sero-epidemiological surveys of flying fox populations indicate that up to 50% of animals may have been exposed to the virus, however the percentage of animals actually carrying infectious virus is likely to be much lower (Tulsiani et al., 2011; Halpin et al., 2000).
  • The incubation period for clinical infection in horses ranges from 48 hrs to 16 days (Tulsiani et al., 2011).

Bats are attracted to fruiting and flowering trees. A favourite source of feeding includes fig trees, fruiting palms and native trees in flower. High risk areas include areas directly under trees where bats congregate to feed. Hendra virus is transmitted from urine and placental material of infected bats to horses. It can subsequently be transmitted between horses, and from infected horses to humans, through body fluids (saliva, blood, urine etc).

It is reported that under favourable conditions (i.e. 22°C, pH neutral) the virus may last up to five days on fomites (inanimate substances with potential to harbour and transmit infectious diseases, e.g. tack, clothing, water-troughs). The Queensland Department of Agriculture and Fisheries has taken a precautionary approach and advises that the risk period of the virus may be up to 10 days (El Saadi et al., 2011).

Infected horses may be asymptomatic for two days but have the potential to excrete the virus through nasal secretions during this time, and therefore may be infectious for up to two days before displaying clinical signs of the disease (Middleton, 2009). HeV may be present in respiratory secretions, saliva, urine and faeces, blood and throughout body tissue. By the time a horse is showing clinical signs of HeV infection, it may be systemically widespread throughout the body and body fluids. There is currently no vaccine or guaranteed treatment for HeV once contracted in humans.

All of the seven cases of human infection with HeV that have been recorded had exposure either during necropsy of infected horses or from close contact with infected horses. In all cases, HeV was not considered as a possible infection, and exposure had occurred before the horse was confirmed to have HeV. Four of these people died as a result of HeV infection. The symptoms in humans may present as severe influenza which may include headaches, fever, sore throat, coughs and tiredness, which can progress to pneumonia. There is also a risk that the infected person may develop encephalitis (inflammation of the brain) (Qld Health Hendra Virus Infection; Murray et al. 1995; Tulsiani et al., 2011). The virus does not stay localised, but spreads systemically throughout all tissue primarily causing necrosis of blood vessels, and oedema in lung tissue (Murray et al., 1995).

An occurrence of HeV infection within The University of Queensland could have devastating consequences, potentially resulting in loss of life to horses and humans, and/or adversely affecting reputation, research and education. In the event of an occurrence, the University would be expected to abide by the recommendations of the Queensland Department of Agriculture and Fisheries and Workplace Health and Safety Queensland.

7. HeV Vaccine

Equivac HeV is a non-infectious formulation of a recombinantly expressed subunit vaccine comprising the virus surface protein G, developed originally by scientists at the USAMRID and later transferred to CSIRO (Pallister et al., 2011). Immunisation induces the production of neutralising antibodies that provide protection if the animal is subsequently exposed to live virus.

The vaccine, available from Zoetis®, has been available for use on horses from 13 November 2012. Only accredited veterinarians may administer the vaccine under a Minor Use Permit (AVA vaccine article ;"What vets need to know about the Hendra virus vaccine").

7.1 Vaccination implementation

The recommended vaccination protocol stipulates two vaccinations 21 days apart, followed by a periodic booster-vaccination (this is either biannual or annual, your veterinarian will be advised appropriately by Zoetis®). Currently it is recommended that pregnant mares and foals under four months of age should not be vaccinated. Furthermore, it is a requirement that all vaccinated horses are microchipped.

This implementation strategy is in support of current HeV management practices in place at the Equine Unit at the Gatton Campus and on the Pinjarra Hills farm as per ‘The University of Queensland, School of Veterinary Science Biosecurity and Infection Control Procedures:  Equine Hospital-Gatton' (Van Eps, 2011). These management practices will remain in effect.

Below are target horse groups applicable to the UQ Gatton Campus and the Pinjarra Hills farm:

7.1.1 Student-owned horses

Mandatory requirement for vaccination prior to entry.

  • Proof of vaccination is required (i.e. veterinary certificate). This is the responsibility of the horse owner (i.e. student), who will bear all costs of the vaccinations.
  • Implementation is required immediately, with no student-owned horses permitted on campus until the full course of vaccinations has been delivered.
  • A vaccine booster is to be administered every 6 months and proof supplied.

7.1.2 Teaching horses

Mandatory requirement for vaccination prior to entry into the teaching herd.

  • Implementation required immediately, all current teaching animals require full vaccination prior to first semester.
  • If the animals are to be retained for a prolonged period, then a booster vaccination is to be administered every 6 months and proof supplied.

There are currently two categories of equine teaching herds on the Gatton Campus belonging to:

  • School of Veterinary Sciences (SVS), cost of the vaccines and associated costs are the responsibility of SVS.
  • Office of the Director Gatton Campus and School of Agriculture and Food Sciences (SAFS), costs of the vaccines and associated costs are the responsibility of the respective areas.

7.1.3 Research horses

Mandatory requirement for vaccination prior to induction into a research trial.

  • All current research stock at the Gatton Campus and Pinjarra Hills site (other than brood mares; see below) are to be vaccinated before first semester.
  • If pre-vaccinated research mares/stallions cannot be procured, it will be required that they are vaccinated immediately upon delivery to either the Gatton Campus or Pinjarra Hills and before they enter into any research project. The exception to this would be horses procured for short‑term terminal studies (no more than 1-2 weeks duration ending with euthanasia, any longer than this will require vaccination), which would be managed under current HeV management practises.

7.1.4 Outside horses

These include ‘demonstration’ horses and miscellaneous horses which are brought onto the Gatton Campus for a limited period of time.

Mandatory requirement for vaccination prior to entry.

  • Proof of vaccination is required (i.e. veterinary certificate). This is the responsibility of the horse owner (i.e. student), who will bear all costs of the vaccinations.
  • Implementation is required immediately, with no student-owned horses permitted on campus until the full course of vaccinations has been delivered.
  • A vaccine booster is to be administered every 6 months and proof supplied.

7.1.5 Internal brood mares (UQ stock – research stock)

The restrictions on the administration of the HeV Vaccine include that no pregnant mares are to be vaccinated.

  • A progressive vaccination program will be administered with consideration to the brood mares gestational status.
  • Foals under 4 months of age are not to be vaccinated (see above).  As such, foals will be vaccinated at the weaning stage, which will be administered along with the standard vaccinations given at approximately 6 months of age, the cost of which will be the responsibility of the relevant School or Unit, or owner.

7.1.6 UQ VMC patients/cases

A variety of cases are presented throughout the year including reproduction cases (mares and foals) from the Equine Hospital (SVS), and other emergency cases. Hospital patients, with approval from the Manager of the Equine Unit, may present for agistment in the Equine Unit facility. The equine hospital is currently considering changing the rules for intake of sick horses, i.e. limiting intake to horses that are referred by a vet and that have proof of vaccination. Current HeV management practices are detailed in ‘The University of Queensland, School of Veterinary Science Biosecurity and Infection Control Procedures: Equine Hospital-Gatton’ (Van Eps, 2011).

7.2 Administration of the HeV vaccine at the Gatton Campus and Pinjarra Hills farm

There are several equine veterinarians at the School of Veterinary Sciences, Gatton Campus, who are licenced to administer the HeV vaccine. The Equine Hospital at SVS also currently holds stock of the vaccine and can be expected to do so henceforth.

Caveat:

At the present time the vaccine is not fully registered, and Zoetis® Animal Health will not accept liability for any adverse effects of the vaccine. UQ has considered the risks involved and decided to proceed regardless of Zoetis® position. Consequently, UQ may have to assume responsibility for, and absorb the costs of, any adverse effects on its own horses. In order to minimise its own exposure, UQ in turn will ensure that any non-UQ horse that is vaccinated is done so on the basis that the animal’s owner agrees that UQ will not be liable for any adverse effects. The circumstances of any incident should be considered individually and advice sought if there are any grounds upon which UQ believes Zoetis® Animal Health or a third party should be responsible or liable.

Please refer to the product safety data sheet for further information.

7.3 Enforcement and oversight of HeV vaccinations:

  • Gatton Campus: the UQ Gatton Equine Unit and registered veterinarians from The UQ Veterinary Medical Centre (UQ-VMC)
  • Pinjarra Hills: Faculty of Science with assistance from registered veterinarians from UQ-VMC
  • This procedure will be overseen by the UQ OHS Division in consultation with the UQ IBC and relevant operating units such as the Office of the Director Gatton Campus and the Faculty of Science.​

8. Reference Material

Australian Veterinary Association. Equivac HeV vaccine for horses.

AUSVETPLAN, Summary Document v3.1, 2008.

El Saadi D, Field H, Thompson F, Reid P, Wilson J, Coward P, Donohue S, Ailworth A, Appuhamy R, Nelson K, 2011, Hendra Virus Infection Prevention Advice, Hendra Virus Interagency Technical Working Group

Field HE, Barratt PC, Hughes RJ, Shield J, Sullivan ND, 2000, A fatal case of Hendra virus infection in a horse in north Queensland: clinical and epidemiological features, Australian Veterinary Journal 78(4): 278-80.

Field H, 2009, Hendra virus re-visited, Virologica Sinica 24(2):105-109

Halpin K, Young PL, Field HE, MacKenzie JS, 2000, Isolation of Hendra virus from pteropid bats: a natural reservoir of Hendra virus, The Journal of general virology 81:1927-1932

Middleton D, 2009, Initial experimental characterisation of HeV (Redland Bay 2008) infection in horses, CSIRO Australian Animal Health Laboratory (AAHL)

Murray K, Sellek P, Hooper P, Hyatt A, Gould A, Gleeson L, Westbury H, Hiley L, Selvey L, Rodwell B, Ketterer P, 1995, A morbillivirus that caused fatal diseases in horses and humans. Science 268: 94-97

Queensland Government, Hendra virus infection

Queensland Government, Hendra virus information for industry and horse owners

Queensland Government, Summary of Hendra virus incidents in horses

Queensland Government, Veterinarian guidelines and assistance for handling Hendra virus in horses

Queensland Ombudsman's report on The Hendra Virus Report: An investigation into agency responses to Hendra virus incidents between January 2006 and December 2009

Pallister J, Middleton D, Wang LF, Klein R, Haining J, Robinson R, Yamada M, White J, Payne J, Feng YR, Chan YP, Broder CC, 2011, A recombinant Hendra virus G glycoprotein-based subunit vaccine protect ferrets from lethal Hendra virus challenge. Vaccine 29(34):5623-5630.

Tulsiani SM, Graham GC, Moore PR, Jansen CC, Van Den Hurk AF, Moore FA, Simmons RJ, Craig SB, 2011, Emerging tropical diseases in Australia. Part 5. Hendra virus. Annals of Tropical Medicine & Parasitology 105:1-11.

Van Eps A, 2011, The University of Queensland, School of Veterinary Science Biosecurity and Infection Control Procedures: Equine Hospital-Gatton (internal document available by request from the Office of the Faculty of Science).

9. Contact for additional information

Biosafety Advisor
UQ OHS Division
Phone: 336-52365
biosafety@uq.edu.au

Custodians
Director, Occupational Health and Safety
Mr Jim Carmichael
Custodians
Director, Occupational Health and Safety
Mr Jim Carmichael