Australian bat lyssavirus overview

Under Queensland legislation, if you suspect an animal is clinically ill with ABLV or if an animal has been bitten or scratched by a bat or other animal known to be infected with ABLV, you must report it to Biosecurity Queensland on 13 25 23 or contact the Emergency Disease Watch Hotline on 1800 675 888.

You do not need to notify us about animal contact with a bat unless the bat is known to have ABLV.

Australian bat lyssavirus (ABLV) is a virus endemic in Australian bats that causes invariably fatal encephalitis (infection and inflammation of the brain) in bats, humans and other animals.

The natural history of ABLV is similar to rabies. There are two 2 closely related variants (types) of ABLV:

  • Pteropid-ABLV in flying foxes
  • YBST-ABLV in yellow-bellied sheathtail bats.

Other, unrecognised, variants may also be present in other bat species.

The risks of ABLV infection in humans and animals can be minimised by avoiding contact with bats, and seeking urgent medical or veterinary advice about the use of rabies vaccines to prevent disease.

Overview

Cause

A virus of the family Rhaboviridae that is closely related to the classical rabies virus found overseas.

Distribution in Queensland

ABLV has been reported only in Australia and is considered to be present in all populations of Australian bats. It is likely that variants of ABLV also occur in bats in South East Asia.

In May 2013, 2 horses were confirmed as being infected with ABLV on a property in South East Queensland. These were the first known cases of ABLV in an animal other than a bat.

There have been 3 human cases of disease due to ABLV. All were fatal.

Lifecycle

Clinical ABLV disease occurs after a variable incubation period, which can be from 10 days to many months or years. The virus does not survive for more than a few hours outside an infected animal.

Lyssaviruses are usually transmitted by a bite or scratch from an infected, clinically ill animal.

Infection of other mammals (e.g. horses, dogs or cats) could pose a risk of transmission to humans.

No carrier state has been demonstrated.

Affected Animals
  • bats; horses; humans;
  • potentially any other mammal that is adequately exposed could be affected

Hosts

The virus has been found in 4 common species of flying fox:

  • black
  • greyheaded
  • little red
  • spectacled

It has also been found in yellow-bellied sheathtail bats (Saccolaimus flaviventris - an insectivorous microbat).

Antibodies have been found in some other species of microbat, suggesting other microbat species may also be hosts.

Symptoms

Bats


ABLV infection produces a range of clinical signs of central nervous system disease including

  • paresis (weakness) and an inability to fly, hang properly, swallow properly or move about
  • paralysis - most obvious in the hind limbs
  • seizures, tremors
  • unusual vocalisation or incessant licking
  • changes in behaviour, including agitation, aggression and approaching people (it is rare for healthy bats to approach people).

Fewer than 20% of bats infected with ABLV show signs of abnormal aggression or approaching people.

Other animals

Other animals infected with ABLV are expected to show clinical signs consistent with encephalitis in that species. Clinical signs in non-bat animals are likely to be similar to ABLV in bats or the signs of rabies in non-bat species.

Impacts

Clinical disease is invariably fatal.

ABLV is a zoonosis that can be fatal in humans.

How it is spread

ABLV is shed in the saliva. Like the rabies virus, it is presumed that ABLV is usually transmitted by bites or contamination of a fresh wound, scratch, or mucous membranes with infected saliva.

There is no known risk of contracting ABLV from bats flying overhead, contact with bat urine or faeces blood. There is no evidence to suggest ABLV could be contracted by eating fruit partially eaten by a bat. Any fruit that has been partially eaten by any animal should not be eaten as it could be contaminated by a variety of germs.

There is no significant risk of exposure from living, playing or walking near bat roosting areas.

Risk period

Infection is rare.

Research indicates that ABLV is present in less than 1% of all free-living bats. ABLV infection is more common in sick, injured or orphaned bats. Of those sick or injured bats with signs of central nervous system disease, up to one-third are infected with ABLV. Domestic animals, including horses, dogs and other pets may potentially be exposed to ABLV through contact with bats. The similarity of ABLV with other lyssaviruses suggests that, on rare occasions, exposure may lead to clinical ABLV disease.

Monitoring and action

Avoid handling a live bat yourself. Only rabies vaccinated people who are experienced in handling bats should rescue or examine a bat.

If a bat needs help, contact the RSPCA on 1300 ANIMAL (1300 264 625) or a local volunteer wildlife care organisation for help to safely collect a live bat.

Contact your local veterinarian if you suspect that your pet might have been bitten or scratched by a bat.

Information for veterinarians about minimising the risk of ABLV infection in animals is available online.  If you suspect a bat or other animal is infected with ABLV, isolate the animal, limit its contact with humans and other animals and monitor the animal's health.

If the animal develops clinical signs suggestive of ABLV, it should be euthanased and tested for ABLV.

Options for managing animals potentially exposed to ABLV through bat contact include:

  • post-exposure vaccination of the animal with rabies vaccine - to prevent development of clinical disease. Your veterinarian can contact Biosecurity Queensland to access the vaccine and will advise on the measures you must take to manage the risks
  • observation for clinical signs suggestive of ABLV infection - with reporting of a suspicion of clinical ABLV disease to Biosecurity Queensland if signs suggestive of ABLV occur
  • euthanasia.

What to do if bitten or scratched by a bat

Infection in people is extremely rare. While there is no effective treatment once a person is clinically ill, prompt action following a bat bite or scratch can prevent clinical disease.

  1. If bitten or scratched by a bat, do not scrub the wound. Immediately wash the wound gently but thoroughly for at least 5 minutes with soap and water. If available, apply an antiseptic with anti-virus action, such as povidone-iodine, iodine tincture, aqueous iodine solution or alcohol (ethanol), after washing.
  2. If bat saliva gets in the eyes, nose or mouth, or broken skin, flush the area thoroughly with water.
  3. Seek urgent medical advice from a doctor or nearest hospital.

Post-exposure rabies vaccinations and other treatments may be necessary if you have been bitten or scratched by a bat. No person who has received post-exposure prophylaxis (vaccinations) has developed clinical disease.

Control

Rabies vaccination is presumed to provide cross-protection against ABLV in humans and animals.

There is no treatment for animals. Death is inevitable once clinical signs appear.

Bats and other animals suspected of having clinical ABLV disease should be euthanased and tested.

Bats

Effective long-term control of lyssaviruses requires vaccination of the host-species population. Eradication of ABLV through vaccination of bats is not possible due to an inability to vaccinate free-living bats. Culling flying foxes would not control or eradiate ABLV.

Information for bat carers

The following guidelines can reduce the likelihood that a bat with clinical ABLV disease has opportunity to transmit ABLV to other captive bats.

  • Bats that are new to a facility (in particular rescued sick, injured or orphaned bats) should be held separately for at least 1, preferably 3, days prior to being housed with other captive bats. Bats that do not show signs suggestive of ABLV after 1-3 days of separation can be assumed to have a lower (but still not zero) likelihood of being infectious with ABLV and so suitable to be housed with other bats.
  • If, during the 1-3 days of separation, the bat displays behavioural or other clinical signs that are unusual or suggestive of ABLV, the bat should continue to be held separately for up to 10 days.
  • Where logistics preclude holding every new bat separately (e.g. during periods of high intake), contact between bats during the first 3-10 days of each bat's care should be limited as much as possible, e.g. by managing bats in small stable groups until all bats in a group have been observed for at least 3, preferably up to 10, days.
  • During periods of high intake - any bat rescued with a history, behaviour or clinical signs suggestive of ABLV should be held separately while others (e.g. those with a high likelihood of a non-ABLV cause for rescue, e.g. tick paralysis, heat stress) are managed in small groups.
  • At any time - bats that die or are euthanased following clinical signs suggestive of ABLV of less than 10 days duration should be submitted for laboratory testing.

Other animals

Prevent pets and other animals from coming into contact with bats. This may include keeping dogs and cats inside at night, particularly when bats are feeding on fruiting or flowering trees on your property.

Humans

Avoid contact with live bats (including flying foxes). If you come across a bat alone or an injured, sick or orphaned bat, do not touch it.

Contact:

  • the RSPCA on 1300 ANIMAL (1300 264 625)
  • a local volunteer wildlife care organisation.

Contact the RSPCA or your veterinarian for advice about dealing with dead bats.

Only rabies-vaccinated people should handle live bats.

Vaccinated people should be trained to handle bats safely and wear protective clothing (long sleeves, long pants, shoes and puncture resistant gloves) to avoid being bitten or scratched.

If you have occupational contact with bats or ABLV, including if you are a wildlife carer, veterinarian or scientist working with ABLV, seek medical advice about pre-exposure rabies vaccination.

For further medical information, please contact your local doctor, nearest public health unit, or the 13HEALTH information line (13 432584).

More information

Last updated 09 December 2016