Hendra virus

CDNA National guidelines for public health units

Last updated: 08 December 2011

1. Summary

Public health priority
Urgent.

Case management

• Respond to a confirmed human case immediately on notification
  • Ensure appropriate infection control measures are in place.
  • Ensure that liaison with an infectious disease physician occurs
• Respond to a confirmed equine case, or where heightened suspicion of infection in a horse exists as advised by the relevant animal health agency, immediately on notification.
  • Ensure appropriate infection control measures are in place.
• Establish a team, including public affairs officer, to manage the public health response for any confirmed human or equine case.
• Close liaison with animal health agencies is necessary - joint meetings should be held with relevant state or territory animal health agencies to ensure a coordinated response. Initial meeting should be held within 24 hours of notification.

Contact management

• Assess exposure.
• If high exposure to body fluids of a confirmed equine case, refer as soon as practicable to an infectious diseases physician for consideration of post-exposure prophylaxis.
• Advise all contacts to seek early medical advice if they develop fever, respiratory or neurological symptoms within three weeks of exposure.

2. The disease

Infectious agents
Hendra virus (previously called equine morbillivirus) is a paramyxovirus of the genus Henipavirus. The only other agent in this genus is Nipah virus.

Reservoir
Fruit bats (Pteropus species), also known as flying foxes, are the only known natural reservoir. The distribution of flying fox species in Australia is shown in Figure 1. All species are susceptible - antibody to Hendra virus has been found in 20-50 percent of flying foxes in mainland Australian populations.^1,2 Since 1994, widespread testing involving 46 other species of animals and arthropods has not shown the natural presence of the virus in any species other than flying foxes.

Figure 1: Distribution of Pteropus species (flying foxes) on mainland Australia ³
Pteropus species (flying foxes) on mainland Australia ³"/>

Horizontal hatching = P. alecto
Vertical hatching = P. poliocephalus
Solid black = P. conspicillatus
Broken line = southern inland limit of P. scapulatus.


*Note that flying foxes are nomadic animals and changes in distribution may occur, e.g. the range of grey headed flying foxes has historically extended west into parts of South Australia including Adelaide on a periodic basis

Mode of transmission

Bat-to-horse
Spill-over from flying foxes to horses is rare (32 documented events from 1994 to October 2011, 9 in NSW and 23 in Queensland), possibly occurring through contamination of horse-feed by infectious fluids from bats, e.g. bat urine/reproductive products. At the time of the original outbreak at Hendra (in Brisbane, Queensland) in 1994, testing of nearly 2,000 horses across Queensland, including 906 within 1 km of the quarantined properties found no seropositive horses apart from those on the quarantined premises, i.e. no evidence of other spillover events.⁴

Horse-to-person
Only seven human cases have been documented (as of September 2011). All seven had a high level of exposure to respiratory secretions and/or other body fluids of horses subsequently diagnosed with Hendra virus infection, or presumed to have Hendra virus infection through review of clinical/epidemiological evidence in the absence of samples for laboratory testing. Three of the cases were exposed to tissues during post mortem examinations on those horses. Two were probably exposed while performing nasal cavity lavage in the days immediately before the horse showed any clinical signs of disease. Further details on these cases are presented in Appendix 1. No cases have been documented in people with medium or lower exposure levels, including anyone appropriately using personal protective equipment,⁵ and not all people with high exposures have become infected. On the evidence available, the most likely mode of transmission is via substantial direct exposure of mucous membranes (or non-intact skin) to respiratory secretions (including large droplets) or blood from an infected horse. Indirect exposure to respiratory secretions or blood, and direct or indirect exposure to other body fluids, may contribute to overall transmission risk. Current evidence does not support airborne exposure as a significant mode of transmission.

Horse-to-horse
Has mainly occurred in situations of close contact. Transmission between horses has been more efficient in stabled situations, with spread between multiple horses occurring in all stabled situations to date - Hendra (1994), Redlands (2008) and Cawarral (2009), all in Queensland (see Appendix 1). It is possible that short-term survival of Hendra virus on environmental surfaces and inadvertent human-assisted fomite transmission (e.g. horse gear or veterinary equipment contaminated with secretions or fluids of an infected horse) may contribute to more efficient transmission in stabled situations. Of the 20 equine cases associated with the 1994 outbreak in Hendra, 18 were from the index property and the other two were from the immediately adjacent property.

Bat-to-person
No evidence that this occurs. A study of 128 bat carers, the majority of who reported daily contact with bats and/or a history of bat bites, found no individuals with antibodies to Hendra virus.⁶

Person-to-person
No evidence that this occurs. Serological testing in 169 health care worker and 4 household contacts of the first three human cases found no individuals with antibodies to Hendra virus.⁷ Testing of contacts of the subsequent four human cases has also produced uniformly negative results.⁸ However it is desirable to avoid close contact with respiratory secretions and other body fluids of symptomatic human cases. Standard contact and droplet precautions⁹ should be implemented for management of suspected or confirmed human cases.

Person-to-horse
No evidence that this occurs. However it is desirable for suspected human cases to avoid close contact with horses until the diagnosis has been clarified.

Experimental
Disease has been induced under experimental conditions in cats, ferrets, hamsters, guinea pigs, horses and pigs. Experimentally infected horses can excrete viral RNA in nasal secretions for at least two days before showing clinical signs of disease. ^5,10 This underpins recommendations that any procedures on apparently healthy horses that may cause aerosolisation or splashes should be performed with appropriate infection control precautions including personal protective equipment.

Other
A single dog developed antibodies to Hendra virus on a property where three horses developed Hendra virus infection in July 2011. Although the source of exposure for the dog cannot be definitively ascertained, horse-to-dog transmission is the most plausible scenario given the dog had potential opportunity for exposure to infected horses. There is no evidence that bat-to-dog or dog-to-person or dog-to-horse transmission occurs.

Incubation period
Current limited evidence suggests that the incubation period in humans is between 5 and 21 days.

Horses
The incubation period in horses appears to be 5-16 days, although the incubation period in one horse in the 2009 Bowen event may have been 31 days (personal communication, Steven Donohue [Queensland Health] and Hume Field [Biosecurity Queensland] November 2009).

Infectious period
Humans
Unknown in humans, as no evidence of person-to-person transmission to date. While the risk of transmission is probably negligible, for public health purposes human cases should be considered potentially infectious while symptomatic.

Horses
For human public health purposes, horses should be considered potentially infectious from 72 hours prior to onset of clinical signs of disease until death (by disease or euthanasia) and safe disposal of the carcase¹⁵ has been completed. Careful assessment is required of how closely the horse was observed for the onset of illness. It is unclear whether horses recovered from illness remain infectious or are capable of permanently clearing the virus.

Clinical presentation
Humans
The documented human cases to date have presented with:

• self-limiting influenza-like illness (two cases)
• influenza-like illness complicated by severe pneumonic illness contributing to death (one case)
• aseptic meningitis with apparent recovery, then death from encephalitis 13 months later (one case)
• acute influenza-like illness followed by encephalitis at seroconversion, followed by recovery (one case) and death (two cases).

Further detail on these seven cases is included in Appendix 1.

No cases of asymptomatic infection have been identified from extensive testing of human contacts associated with Hendra virus events up to September 2011.

Horses
In horses, Hendra virus has a clear predisposition for targeting endothelial cells of blood vessels, with clinical signs dependent on the sequence in which organs are affected. Documented equine cases to date have typically presented with acute onset of clinical signs, including increased body temperature and increased heart rate, and rapid progression to death associated with either respiratory or neurological signs or a mix of these; some horses have also shown evidence of multi-organ involvement. The clinical signs, particularly of early Hendra disease, may be non-specific, although progression from onset to death is typically rapid, over a couple of days. Less severe infections have been identified in horses being monitored during an outbreak; these horses are typically second or third generation cases. From figures to date, approximately 75% of infected horses can be expected to die. Those that survive often have mild signs and seroconvert during the recovery period. The current AUSVETPLAN policy for Hendra virus infection prescribes euthanasia for all horses that test positive,¹¹ as they may remain infectious or relapse and become infectious. Refer to the Biosecurity Queensland Guidelines for veterinarians handling potential Hendra virus infection in horses⁵ for more information on clinical presentation.

Persons at increased risk of disease
People who are more likely to be exposed to infected horses may be at increased risk e.g. veterinarians, horse trainers, stable workers.

Disease occurrence and public health significance
The number of equine and human cases in the 32 events known to have occurred up to September 2011 are summarised in Appendix 1. All of these events have occurred in Queensland or New South Wales. However given the distribution of flying foxes (Figure 1) and frequency of horse movements between states and territories, cases could occur anywhere in Australia.

3. Routine prevention activities

• Veterinary practitioners and staff handling confirmed or suspected equine cases or conducting post mortem examinations on the carcase of a confirmed or suspected case should wear appropriate personal protective equipment and take preventive hygiene measures (refer to the Biosecurity Queensland Guidelines for veterinarians handling potential Hendra virus infection in horses⁵).
• Horse owners or carers should minimise unnecessary human contact with sick horses and take appropriate preventive hygiene measures (refer to the Workplace Health and Safety Queensland document Hendra virus - information for horse properties and other horse related businesses¹²).
• Horse owners and carers can take steps to protect horses from becoming infected with Hendra virus by reducing exposure to bats, e.g. by placing feed bins and water troughs under cover and away from areas where bats feed or roost (refer to the Workplace Health and Safety Queensland document Hendra virus - information for horse properties and other horse related businesses¹² and the Queensland Horse Council website at http://www.qldhorsecouncil.com/default.aspx.

4. Surveillance objectives

• To identify equine and human cases so that appropriate contact tracing and public health measures can occur.
• To collect information about new human cases in order to broaden understanding of this high profile emerging infectious disease.

Surveillance for equine cases is primarily the responsibility of animal health agencies. Appropriate processes should be in place to ensure relevant surveillance information is shared promptly at state and territory level between animal and human health agencies.

5. Data management

In states and territories where Hendra virus infection is notifiable, confirmed human cases should be entered onto the notifiable diseases database, ideally within one working day following notification.

6. Communications

• As soon as practicable and ideally within one hour of notification, notify the state or territory communicable diseases branch (CDB) of confirmed human or equine cases.
• As soon as practicable and ideally within four hours of notification, state/territory CDB should notify the relevant animal health authority of any confirmed human case.
• As soon as practicable and ideally within one working day, the state/territory CDB should notify case details and response plan to the CDNA secretariat.

7. Case definition

Hendra virus infection in humans is not currently nationally notifiable and there is no national case definition. The following is based on the Queensland case definition as of October 2011.

Confirmed case
A confirmed case requires laboratory definitive evidence
OR
laboratory suggestive evidence and epidemiological evidence and clinical evidence.

Laboratory definitive evidence
Isolation of Hendra virus
OR
detection of Hendra virus by nucleic acid testing

Laboratory suggestive evidence
Detection of antibody to Hendra virus by microsphere immunoassay, confirmed by specific immunofluorescent assay
OR
detection of antibody to Hendra virus by virus neutralisation test

Epidemiological evidence
Exposure, within 21 days prior to onset of symptoms, to a horse with confirmed Hendra virus infection, or where heightened suspicion of Hendra virus infection exists as advised by the relevant animal health agency.

Clinical evidence
Clinically compatible acute illness (see clinical presentation section above)

NB: For case definitions in horses see Guidelines for veterinarians handling potential Hendra virus infection in horses. Biosecurity Queensland, 2010. Available at: http://www.dpi.qld.gov.au/4790_13371.htm

8. Laboratory testing

Human testing may be indicated when:

• There has been exposure to confirmed or suspected equine cases; or
• There is compatible human illness and testing is performed after consultation with an infectious diseases physician.

Nucleic acid testing
NAT can be performed on respiratory samples (deep nasal swab or nasopharyngeal aspirate), serum (preferable to blood), cerebrospinal fluid, urine and tissue samples.
Minimum CSF, serum, liquid respiratory or urine sample volume is 0.5ml.
Tissue samples (minimum rice grain size) should be in viral transport medium, not fixed. Respiratory swab samples should be in viral transport medium. Chill all samples immediately upon collection (4^oC) and transport cool (4^oC), not frozen, within 24 hours.

Serology
QHFSS currently performs a screening microsphere immunoassay (MIA) for IgM and IgG and has the capability of differentiating individuals with natural antibodies from those administered therapeutic monoclonal antibodies. If positive, this is followed by a confirmatory immunofluorescence assay (IFA) that can be quantified. As with all serological tests, false positive results can occur. If MIA and IFA are positive in the absence of positive NAT, and there is any question as to whether this represents true infection, specimens may be referred to AAHL for VNT. Where serological testing is indicated, a baseline sample should ideally be collected as early as possible after exposure and stored for testing in parallel with subsequent samples. Minimum sample volume of CSF or serum is 0.2ml. Transport cool (4^oC) within 24 hours.

The earliest laboratory evidence of infection in human Hendra virus cases has been positive nucleic acid testing in blood, respiratory specimens, then urine, with serology becoming positive two to five days after onset of symptoms.

Recommendations:
For suspected human cases

• As a minimum, collect blood and urine for NAT.
• Additional tests, depending on clinical picture may include deep nasal swab, nasopharyngeal aspirates and/or CSF for NAT. Tissue samples can be collected post-mortem (or by pre-mortem biopsy where relevant) for NAT.
• Serology should be considered whenever there is a high index of suspicion (e.g. high level exposure to a confirmed equine case) or where NAT could potentially be less reliable e.g. due to duration of symptoms greater than one week.

For human contacts of an equine case

• If high exposure level, collect baseline serology and store for testing in parallel with follow up samples at 3 and 6 weeks after last exposure.
• If medium or lower exposure level, assess if symptoms develop and test as for suspected cases above where indicated.

9. Case investigation

Response times
Investigation
Commence investigation immediately on notification of a confirmed human or equine case, or where notified by an animal health authority of heightened suspicion of infection in a horse on clinical/epidemiological grounds.

Response procedure
Case investigation - confirmed or suspected equine case
On notification of a confirmed equine case, or where an animal health agency has heightened suspicion on clinical and epidemiological grounds:

• Liaise with the animal health agency to:
  • Ensure appropriate infection control measures⁵ including cessation of other than absolutely necessary human contact are in place for all confirmed equine cases and any horses that have been in contact with equine cases.
  • Clarify timeline for results of laboratory testing when not already
    confirmed.
  • Establish whether/what communication has occurred with potential
    human contacts.
• Identify and manage human contacts.

Case investigation - confirmed or suspected human case

On notification of a confirmed human case, or where a public health unit considers there is heightened suspicion on clinical and epidemiological grounds:

• Liaise with the treating clinician to:
  • Ensure appropriate infection control measures (see Isolation and
    Restriction section below) are in place.
  • Ensure liaison with an infectious diseases physician occurs.
• Facilitate urgent laboratory testing where not already confirmed.
• Identify any exposures to known equine cases, and other equine exposures where relevant.
• Identify and manage human contacts.
• Liaise with senior staff in the relevant state or territory animal health authority to:
  • Alert them to the human case.
  • Discuss need for testing of relevant horses, where appropriate.
  • Establish whether/what communication has occurred with potential
    human contacts of relevant horses.

Response management - confirmed equine or human case

For all confirmed human or equine cases, a team should be established to manage the public health response. Involve a public affairs officer early and develop clear and consistent public messages. Unless the event is confined to a small property and there are very few human contacts the public health actions are likely to be resource intensive for several weeks.

Close liaison with the relevant state or territory animal health agency is necessary and regular interagency meetings should be held to ensure a coordinated response. The initial meeting should be held within 24 hours of notification. Relevant state or territory workplace health and safety agencies should be involved early if the event occurs in a workplace.

Case treatment

Responsibility of the treating medical practitioner. Advice should be sought from an infectious diseases physician.

Education

Cases should be informed about the nature of infection, mode of transmission and other relevant information. Refer to general fact sheet for disease (Appendix 2).

Isolation and restriction

• While there is no evidence of human to human transmission, standard, contact and droplet precautions ⁹ should be applied for symptomatic persons suspected or known to be infected with Hendra virus. Additional precautions may be ordered at the discretion of the treating infectious diseases physician.
• Confirmed cases, for the duration of acute illness, should avoid close contact with animals.
• Confirmed cases should never subsequently donate blood or any other tissue, even if they fully recover.

10. Control of environment

Measures to ensure the cessation of further inadequately protected equine or human contact with confirmed or potential equine cases on an affected property are the responsibility of the relevant state or territory animal health authority. As per the Biosecurity Queensland Guidelines for veterinarians handling potential Hendra virus infection in horses,⁵ such measures include isolation/euthanasia of infected horses with appropriate disposal of carcases, and quarantine of horses from relevant properties. A log of people visiting or working on the property should be maintained.

In human health care facilities environmental cleaning procedures should be conducted in accordance with Australian Infection Control Guidelines.⁹

11. Contact management

Identification of contacts
The aim of identifying contacts is to:

• Assess their exposure and provide advice about their level of risk and other relevant information.
• Refer for consideration of post-exposure prophylaxis where appropriate.

Contact definition
Contact of equine case

• People who have had direct or indirect exposure of skin or mucous membranes to body fluids of a horse determined by the relevant state or territory animal health authority to be a confirmed case of Hendra virus infection,⁵ or of a horse where heightened suspicion of infection exists on clinical/epidemiological grounds as advised by the relevant animal health authority.

Contact of human case

• People who have had close contact with a symptomatic confirmed human case or person where heightened suspicion of infection exists on clinical and epidemiological grounds as determined by the relevant public health unit (including household or household-like contacts, sexual partners, and anyone with direct or indirect exposure of skin or mucous membranes to secretions or body fluids).

Investigation
Exposure assessments of human contacts are required in relation to all confirmed equine cases of Hendra virus infection, and where heightened suspicion of infection in a horse exists on clinical and epidemiological grounds as advised by the relevant animal health authority. Exposure assessment of human contacts of confirmed human cases is also recommended - although risk is generally likely to be negligible, assessment and reassurance will often be of benefit.

Obtain from relevant state or territory animal health agency information on all horses with confirmed Hendra virus infection, and any epidemiologically linked equine cases where heightened suspicion of Hendra virus infection exists on clinical and epidemiological grounds (this may include previously sick horses associated with affected properties). 'Trace back' investigations by the animal health agency of horse movements from affected properties may generate considerable workload for public health units by identifying other humans requiring follow up as contacts of additional equine cases.

Urgent priorities are to obtain a line listing of all people who may have been in contact with confirmed equine cases, or where heightened suspicion of infection in a horse exists on clinical/epidemiological grounds as advised by the relevant animal health authority (contacts of human cases are a lower priority as likely to be at negligible risk), and then to:

• Assess exposure (using exposure assessment form, Appendix 4) and current health status.
• If high exposure to body fluids of a confirmed equine case, liaise with an infectious diseases physician as soon as practicable for consideration of postexposure prophylaxis.
• If assessed as medium exposure, discuss as soon as practicable with other appropriately experienced public health practitioners and infectious diseases physician/s to reach consensus on exposure assessment.
• Refer any symptomatic people to appropriate care.
• Provide information about Hendra virus.
• Counsel about risk.
• Provide advice about testing recommendations (see Laboratory Testing section above).
• Provide advice about self-monitoring of their health, and to seek early medical advice if they develop fever or respiratory or neurological symptoms within three weeks of exposure, phoning ahead of the visit so that appropriate infection control measures can be put in place (see 'Isolation and Restriction' section and fact sheet for contacts 'Hendra virus - information for people who have been exposed to a horse or human infected with Hendra virus' - Appendix 3).

The urgency of response to illness in contacts depends on the assessed level of exposure; clinically compatible illness (respiratory or neurological symptoms) in a person with high exposure to body fluids of an equine case should be urgently assessed by an infectious diseases physician.

Instructions for exposure assessment:

• It is best to refer to horses by their popular (or most commonly used) name, to minimise confusion.
• Determine the level and type of contact between the person and the equine (or human) case/s.
• Assessment of exposure should review activities with any equine cases up to three days prior to the onset of illness in the horse, and with symptomatic human cases.
• Reinterviewing contacts of equine cases may identify useful new information.

Prophylaxis
No drug or product is of proven benefit in humans, although monoclonal antibodies show the most promise (as of October 2011). Monoclonal antibodies have been shown to protect ferrets from serious disease when given 10 hours after exposure to Nipah virus¹³ and when given 10-12 hours after exposure to Hendra virus (personal communication, Deborah Middleton, CSIRO, 20 September 2011). They have also been shown to protect African green monkeys from severe fatal infection when given 72 hours after exposure to a lethal dose of Hendra virus.¹⁴ As the evidence base to inform use of PEP is rapidly evolving, and relates to small scale in vitro and animal model studies and empirical experience in exposed humans, the infectious disease physician (IDP) involved should consult with other IDPs who have experience in Hendra PEP and knowledge of the current evidence base.
Wherever possible, an expert panel of public health practitioners and IDPs with appropriate experience should be convened as part of the incident management process to review all contacts identified as high and medium exposures and advise on provision of monoclonal antibody and logistic issues. The only stock of monoclonal antibodies, as of October 2011, is held in Queensland. Access to this stock for contacts with high level exposures can be sought via the Senior Director, Communicable Diseases Branch, Queensland Health.

Education
Provide information about the disease to all contacts of confirmed human and equine cases, and contacts of horses or humans where heightened suspicion of infection exists on clinical and epidemiological grounds, as respectively advised by the relevant animal health authority or determined by the relevant public health unit. If an equine case is confirmed, it may be appropriate for human health agency officers to visit the property to provide information and support to key people (e.g. owners and managers), and to assist animal health agency staff in providing information to the local community. Any site visit should complement and not delay the full public health response, which focuses on the timely assessment of exposure and current health status of all people who may have been exposed to infected horses, including animal health practitioners, many of whom may not be available on site.

A Hendra event can be extremely stressful for people exposed or otherwise involved. Contributors to the stress responses include:

• Hendra is a rare disease with high mortality rate.
• It is poorly understood with no proven treatment or prophylaxis.
• It is subject to intense and sensationalist media scrutiny.
• The disease is unfamiliar to GPs and local health practitioners.
• It is subject to widespread myths and online misinformation.
• The potential for devastating effects on the business/livelihood of those involved.
• The death or euthanasia of horses and, rarely, other aniamls.

Horse owners are likely to see animal health agency staff with high level personal protective equipment e.g. full length splash-proof overalls, face shields and respirators. Despite reassurance that these are conservative precautions, they may still infer incorrectly that Hendra virus is highly infectious and that they are at high risk of infection and death.

Therefore, contacts and other closely involved persons, such as family members, owners, and others who may have minimal exposure, may require repeated reassurance and information.

Isolation and restriction

• No restrictions are required on the movements or activities of asymptomatic human contacts of an infected animal or human.
• Symptomatic contacts should be managed with standard, contact and droplet ⁹precautions.
• Contacts of an infected animal or human should not donate blood or any other tissue until cleared by absence of illness over three weeks since last exposure (and negative test results where indicated).

12. Special situtuations

Nil

13. References and additional sources of information

1. Australian Biosecurity CRC for Emerging Infectious Disease. Hendra virus research [updated 2009; cited 4 Nov 2010]. Available from:
http://www.abcrc.org.au/pages/programs.aspx?PROGRAMID=48
2. Field H.. The ecology of Hendra virus and Australian bat lyssavirus. PhD thesis, University of Queensland. Available at http://espace.library.uq.edu.au/eserv/UQ:13859/field_thesis_05.pdf
3. Hall L, Richards, G. Flying foxes: Fruit and Blosson Bats of Australia. University of NSW Press LTD: Sydney 2000.
4. Murray K, Rogers R, Selvey L, Selleck P, Hyatt A, Gould A, et al. A novel
morbillivirus pneumonia of horses and its transmission to humans. Emerg Infect Dis; 1995, 1(1):31-33.
5. Biosecurity Queensland. Guidelines for veterinarians handling potential Hendra virus infection in horses. Brisbane, 2011. Available from:
http://www.dpi.qld.gov.au/4790_13371.htm
6. Selvey L, Taylor R, Arklay A, Gerrard J. Screening of Bat Carers for Antibodies to Equine Morbillivirus. Commun Dis Intell; 1996, 20(22):477-78.
7. McCormack JG, Allworth AM, Selvey LA, Selleck PW. Transmissibility from horses to humans of a novel paramyxovirus, equine morbillivirus (EMV). J Infect; 1999, 38(1):22-3.
8. Playford EG, McCall B, Smith G, Slinko V, Allen G, Smith I, et al. Human Hendra virus encephalitis associated with equine outbreak, Australia, 2008. Emerg Infect Dis; 2010, 16(2):219-23.
9. National Health and Medical Research Council. Australian Guidelines for the Prevention and Control of Infection in Healthcare. Canberra, 2010. Available from: http://www.nhmrc.gov.au/guidelines/publications/cd33
10. Middleton D. Initial experimental characterisation of HeV (Redland Bay 2008) infection in horses. CSIRO: 2009. Available from: http://www.dpi.qld.gov.au/documents/Biosecurity_GeneralAnimalHealthPestsAndDiseases/HeV-Initial-experimental-characterisation.pdf
11. Primary Industries Ministerial Council. AUSVETPLAN Response Policy Briefs. 2009. Available from: http://www.animalhealthaustralia.com.au/wpcontent/
uploads/2011/04/RPB3.3-05FINAL27Jul11.pdf
12. Workplace Health and Safety Queensland. Hendra virus - Information for horse properties and other horse related businesses. [updated June 2010; cited 10 August 2011]. Available from:
http://www.deir.qld.gov.au/workplace/publications/alerts/hendra_virus_horse/index.htm
13. Bossart KN, Zhu Z, Middleton D, Klippel J, Crameri G, Bingham J, et al. A
Neutralizing Human Monoclonal Antibody Protects against Lethal Disease in a Page 14 of 23 New Ferret Model of Acute Nipah Virus Infection. PLoS Pathog; 2009,5(10):e1000642.
14. Bossart KN, Geisbert TW, Feldmann H, Zhu Z, Feldmann F, Geisbert JB, et al. A neutralizing human monoclonal antibody protects african green monkeys from hendra virus challenge. Sci Transl Med; 2011, 3(105):105ra03.
15. Selvey L, Wells RM, McCormack J, Ansford A, Murray P, Rogers R, et al. Infection of humans and horses by a newly described morbillivirus. Med J Aust; 1995, 162:642-45.
16. O'Sullivan JD, Allworth AM, Paterson DL, Snow TM, Boots R, Gleeson LJ, et al. Fatal encephalitis due to novel paramyxovirus transmitted from horses. Lancet; 1997, 349(9045):93-5.
17. Hanna JN, McBride W, Brookes DL, Shield J, Taylor CT, Smith IL, et al. Hendra virus infection in a veterinarian. Med J Aust; 2006, 185(10):562-64.

14. Appendices

Appendix 1 - Summary of human cases of Hendra virus infection and Hendra virus infection events, 1994-2011 (as at October 2011).
Appendix 2 - General factsheet.
Appendix 3 - Factsheet for contacts.
Appendix 4 - Exposure assessment form
Appendix 5 - PHU case checklist and PHU checklist