RABIES AND OTHER LYSSAVIRUS INFECTIONS

Public health priority: Urgent

PHU response time: Respond to possible cases on day of notification. Enter confirmed cases on NCIMS within 1 working day.

Case management: Notify the Communicable Diseases Branch. Identify the source of the infection.

Contact management: For persons bitten or scratched by animals in rabies endemic countries, and for persons bitten or scratched by bats in Australia, urgently assess the need for, and facilitate post-exposure prophylaxis.

Last updated: 12 October 2011

1. Reason for surveillance

• To identify cases and their risk factors, and

• To prevent disease in people exposed to infectious animals.

2. Case definition

Lyssavirus - Australian Bat Lyssavirus (ABL)
A confirmed case requires laboratory evidence.

Laboratory evidence

• Isolation of Australian bat lyssavirus confirmed by sequence analysis, or

• Detection of ABL viral RNA in clinical material.

Clinical evidence
Not applicable.

Epidemiological evidence
Not applicable.

Lyssavirus - Rabies
A confirmed case requires laboratory evidence.

Laboratory evidence

• Isolation of rabies virus confirmed by sequence analysis, or

• Detection of rabies viral RNA in clinical material.

Clinical evidence
Not applicable.

Epidemiological evidence
Not applicable.

Lyssavirus - Unspecified
A confirmed case requires:

• Laboratory evidence, and

• Clinical evidence.

Laboratory evidence

• Positive fluorescent antibody test result for lyssaviral antigen on fresh brain smears, or

• Specific immunostaining for lyssaviral antigen on formalin fixed paraffin sections of central nervous system tissue, or

• Presence of antibody to serotype 1 lyssavirus in the CSF, or

• Detection of lyssavirus-specific RNA (other than to ABL or rabies) in clinical material.

Clinical evidence
Acute encephalomyelitis with or without altered sensorium or focal neurological signs.

Epidemiological evidence
Not applicable.

Factors to be considered in case identification
The Australian Animal Health Laboratory at Geelong in Victoria is the reference laboratory for diagnosis of human and animal infection.

3. Notification criteria and procedure

Rabies and other lyssavirus infections are to be notified by:

• Hospital CEOs on clinical diagnosis (ideal reporting by telephone within 1 hour of diagnosis)

• Laboratories on diagnosis (ideal reporting by telephone within 1 hour of diagnosis).

Only confirmed cases should be entered onto NCIMS.

The diagnosis "Lyssavirus - Unspecified", should only be entered where there is insufficient evidence to meet a case definition for Australian bat lyssavirus or rabies.

Note that rabies is subject to the Commonwealth Quarantine Act (1908).

4. The disease

Infectious agents
Viruses of the genus Lyssavirus.

Mode of transmission
Rabies and other lyssavirus infections are typically transmitted by the virus-laden saliva introduced via a bite or scratch of an infectious animal. They are theoretically communicable from person-to-person via saliva. Transmission from contaminated corneal transplantation has been reported.

Timeline
The typical incubation period is 3 to 8 weeks, but can range from 9 days to 7 years depending on the severity and site of the wound.

Clinical presentation
The usual clinical presentation of rabies is a non-specific prodrome of fever, headache, malaise, anorexia, nausea and vomiting for 1 to 4 days followed by signs of apprehension, hydrophobia, encephalitis and brain stem dysfunction. Excess salivation and difficulty swallowing produces the traditional picture of frothing at the mouth. The disease is almost always fatal. Death from respiratory paralysis generally occurs within 2 to 6 days of onset.

Only 2 cases of human Australian bat lyssavirus infection have ever been identified, so the clinical presentation of infection is less certain, although it is thought to be similar to rabies.

5. Managing single notifications

Response times
Investigation
On same day of notification of a confirmed case begin follow-up investigation and notify the Communicable Diseases Branch.

Data entry
Within 1 working day of notification enter confirmed cases on NCIMS.

Within 3 working days of a report of a person requiring post-exposure treatment, complete a Rabies/Lyssavirus Post-Exposure Treatment form on NCIMS.

Response procedure
The response to a notification will normally be carried out in collaboration with the case's health carers. But regardless of who does the follow-up, PHU staff should ensure that action has been taken to:

• Confirm the onset date and symptoms of the illness

• Confirm results of relevant pathology tests, or recommend the tests be done

• Find out if the case or relevant care-giver has been told what the diagnosis is before beginning the interview

• Seek the doctor's permission to contact the case or relevant care-giver

• Review case management.

Case management

Investigation and treatment
Determine animal contacts, both overseas and in Australia. Animals suspected of being infected should be isolated from other animals and humans pending veterinary investigation. If the animal is killed, the head, with minimal damage, should be submitted to the Australian Animal Health Laboratory for testing.

Education
The case or relevant caregiver and contacts should be informed about the nature of the infection and the mode of transmission.

Isolation and restriction
The case should be isolated using Contact Precautions, and Standard Precautions are to be used for handling any body fluids for the duration of the illness. Treatment is supportive.

Environmental evaluation
None usually required.

Contact management

Identification of contacts
Contacts include persons who are exposed to the saliva or neurological tissue of an infectious person.

Contacts also include persons who have been bitten or scratched by:

• potentially infected animals in countries where rabies has been reported

• a bat anywhere in the world.

See the World Health Organization website for epidemiological details of world-wide rabies occurrence in humans and animals by country: http://www.who.int/rabies/rabies_maps/en/index.html

Note that rabies has been endemic in dogs in Bali, Indonesia since September 2008. There is no evidence that animal exposures in Bali prior to August 2008 would have included exposure to rabies. Therefore, PET is not required for animal exposures hat occurred prior to August 2008. Animal bites and scratches since 1 August 2008 require PET.

Investigation and treatment
Post exposure treatment (PET)
- First Aid
Where a person is exposed to a potentially infected animal, the wound should be washed thoroughly as soon as possible with soap and water, a virucidal preparation (e.g. povidone-iodine solution) applied, and the need for tetanus prophylaxis assessed. Proper cleansing of the wound is the single most effective measure for reducing the transmission of classic rabies virus.
- Vaccination
For people who have been previously vaccinated against rabies with a complete three dose pre-exposure course of rabies vaccination (days 0, 7 and 28), PET consists of a total of 2 doses of rabies vaccine (1 ml each) at day 0 and day 3.
People with no previous vaccination against rabies, uncertain previous vaccination history, or where vaccine was given incorrectly (e.g. intradermally - this is correct for pre-exposure vaccination for rabies, but incorrect for pre-exposure vaccination for lyssavirus), PET consists of 5 doses of 1ml of rabies vaccine on days 0, 3, 7, 14 and 28-30, and one dose of human rabies immunoglobulin (HRIG - see below).Vaccine should be given as deep subcutaneous or intramuscular injection in the deltoid area, as rabies neutralising antibody titres may be reduced after administration in other sites. In children, administration into the anterolateral aspect of the thigh is also acceptable. Vaccine should not be administered by the intradermal route.

- Human rabies immunoglobulin (HRIG)
For people with no, incomplete or incorrectly administered previous vaccination against rabies, one dose of HRIG should also be given unless:

• the person has been previously vaccinated against rabies (see above); OR
• the first dose of post-exposure vaccination course was given more than 7 days ago; OR
• the potential exposure to rabies or ABL was over a year ago; OR
• the exposure is only an animal scratch but no bite unless
• the scratch is on the head or neck; or
• the person is immunocompromised; or
• the circumstances reported indicate a higher risk of bat infection (an identified insectivorous bat or a bat that behaved abnormally)

Timing of PET for bat exposures in Australia
PET should be arranged immediately (including urgent after hours ordering / delivery) if:

• the person was bitten on the head or neck by the bat, or
• there were multiple bites or severe local trauma due to bites, or
• the bat appeared to behave abnormally, or
• the bite was unprovoked (for example the person made no attempt to handle the bat).

• was previously immunised against rabies with a complete three dose pre-exposure course of rabies vaccination (days 0, 7 and 21 or 28), or
• was only scratched by the bat, or
• reported that the exposure did not occur recently (within the previous few weeks), or
• was bitten by the bat, and
  • the bite was single/minor and provoked, and
  • the bite was not on the head or neck, and
  • the bat was not behaving abnormally.

Timing of PET for animal exposures overseas
For people exposed overseas to a potentially rabid dog or cat more than 10 days before, if the dog or cat is known to have remained healthy for 10 days after the exposure, then it can be considered not able to transmit rabies, and PET need not be commenced. Where the exposure occurred less than 10 days before, then PET should be administered unless rabies can be excluded in the animal.
Where doubts exist about the accuracy of rabies surveillance in a particular area exposure by bite or inoculation of a mucous membrane with saliva from an animal that appears to be acting abnormally should be considered a risk for rabies.
Note that bat bite or scratch exposures in any country should be considered to pose a risk of lyssavirus infection.

Obtaining PET
PHUs should arrange for delivery of PET to the exposed person's elected doctor based on the above assessment. PET is supplied free of charge by NSW Health (via the NSW Vaccine Centre. PHUs may hold stocks at strategically located hospitals for emergency use). Note that pre-exposure vaccination (PEV) is not the responsibility of the PHU and is not funded by NSW Health. Persons requiring PEV should be referred to their local doctor who can order it through a pharmacy.
To order PET, the PHU should fax a copy of the NSW Health PHU Order Form to the NSW Vaccine Centre (fax 1800 041 528). When ordering after hours, obtain the name, address, telephone and opening hours of the practice to which the vaccine will be delivered, and calculate the required amount of HRIG required (20 IU per kg body mass for all ages) before calling the NSW Vaccine Centre's on call person. For example, a 70 kg person requires 70 kg x 20 IU=1400 IU. HRIG is supplied at a concentration of 150 IU/mL, therefore a 70 kg person requires 1400/150= 9.3mL. HRIG is supplied in 2mL and 10mL vials, therefore either 1 x 10 mL vial or 5 x 2mL vials (10mL) should be ordered for this person (and the dose would be 9.3 mL).
After arranging PET, the PHU should write to the doctor to confirm that delivery has been arranged, asking the doctor to report to the PHU if there are problems in completing the course of vaccine, and recommending that the doctor ensures that details of the administration (including batch numbers) be kept on the patient's medical record (see model letter attached).
Testing the animal
Bats that have bitten or scratched a person should be sent for testing if they can be secured and euthanased without putting further people at risk. Tests are performed by the CSIRO's Australian Animal Health Laboratory (AAHL), Geelong. AAHL advises that results for immunofluorescence and PCR testing on brain tissue can be made available within one working day of sample receipt. Where necessary a weekend service can be arranged if testing is considered urgent.
PHU staff should facilitate the testing. To test the bat, the exposed person should be advised that, without putting themselves or others at further risk, they should take the bat to a veterinarian, who can euthanase it and send it to the State Veterinary Diagnostic Laboratory (SVDL) at the Elizabeth Macarthur Agricultural Institute (EMAI), Woodbridge Road, Menangle NSW 2568 (telephone 02 4640 6327). The SVDL will then forward specimens from the bat to AAHL for testing. For further information about preparation, packaging, labeling, couriers etc. see "Testing bats for lyssavirus"on PopNet.
PET should commence as soon as possible after the exposure for severe bites as described above, but can be delayed for up to 48 hours for minor exposures (as above) while awaiting bat test results. PET can be withheld or ceased if the bat test result is negative. For the PHU to obtain bat test results, the PHU needs to ensure that the submitting veterinarian records PHU contact details on the test request form so that the PHU is also notified of the results.

Education
Advise susceptible contacts (or parents/guardians) of the risk of infection. Handling of bats should be discouraged. If bat handling is a necessary part of a person's work, the person should be trained in bat handling, wear protective clothing and be fully immunised against rabies. Every effort should be made to prevent scratches and bites.
PHUs should consider the value of media releases at strategic times (e.g., before birthing season) to remind the public about the importance of the above.

Isolation and restriction
None.

6. Managing special situations

Domestic animal exposed to a bat
From time-to-time, pet owners report that their pet dog or cat has caught or been exposed to a bat. Available data (i.e., the absence of reported lyssavirus infection in terrestrial animals in Australia) suggests that the risk of infection to the pet is very low. However, the pet may have been bitten, scratched or exposed to bat body fluids from a bat that may have been sick or behaving abnormally. In that case, the owner should be advised to clean any obvious wounds by washing under running water for 5 minutes, and to seek veterinary assistance by contacting their local veterinary practitioner. They should also report the incident by calling the Emergency Animal Disease Hotline on 1800 675 888.
Available data (i.e., the absence of reported lyssavirus infection in terrestrial animals in Australia) suggests that the risk of infection to the pet is very low. This should be carefully explained to the owner. If the pet owner is anxious about their pet's exposure, then testing of the bat can be arranged with assistance from veterinary authorities. If the bat tests positive, there is a remote possibility that the pet could be infected with the virus. Therefore it should be regularly monitored by the veterinary practitioner and watched for any abnormal behaviour or other neurological signs. The incubation of lyssavirus may be very long (up to several years). Veterinary authorities do not recommend post exposure treatment for animals in Australia.
For more information see the NSW Department of Primary Industries factsheet.
http://www.dpi.nsw.gov.au/__data/assets/pdf_file/0010/367255/Bats-and-health-risks.pdf

Sample letter

[PHU letterhead]
[Date]
[Dr's name and address]
[Dr's fax no.]

Dear Dr [dr's surname]

Post-exposure treatment for rabies or Australian bat lyssavirus infection for [patient name], dob:

I am writing to confirm that staff of the ZZZ Public Health Unit have arranged the delivery of [X number of] doses of Rabies Vaccine and/or [Y number of] mls of Human Rabies Immunoglobulin to the following address for post-exposure treatment of [name patient].

[space for practice address]

Your patient should receive, as soon as possible, D mls (E IU) of Rabies Immunoglobulin (based on your estimate of the patient's weight of F kg).

He/She should/did receive a dose of Rabies Vaccine by intramuscular injection into the deltoid area on [date]; you should arrange for subsequent doses to be given on days [A, B, C] from the date of the first dose.

When you record details of the administration of the vaccine and/or immunoglobulin in the patient record, please also record the batch number.

Where there are multiple wounds, the immunoglobulin may be diluted if necessary to ensure infiltration of all wounds. The remainder, if any, should be administered intramuscularly at a site away from the injection site of rabies vaccine. If the wound has healed, the immunoglobulin should be administered in the vicinity of the healed wound (e.g. around the healed scar).

For more information, please see the Australian Immunisation Handbook [see: \,a href="http://www.health.gov.au/internet/immunise/publishing.nsf/Content/Handbook-lyssavirus, p115-6">http://www.health.gov.au/internet/immunise/publishing.nsf/Content/Handbook-lyssavirus, p115-6].
If you have any problems in arranging follow up of this patient for the necessary doses of Rabies Vaccine, or with interpretation and application of the guidelines, please do not hesitate to contact the Public Health Unit (bh: ah: ) for assistance.

Yours sincerely
[name]
Director

encl. [usually sent with info about vaccine etc]