Topic: Australian Bat Lyssavirus
Description
The Australian Bat Lyssavirus (ABL) was first identified in 1996 and has since been found in four species of fruit bats/flying foxes (megachiroptera) and at least three species of insect eating bats (microchiroptera). It is assumed that ALL Australian bats, both the larger flying foxes and the small insect eating bats have the potential to transmit lyssavirus to humans. Seven types of lyssavirus are recognised throughout the world of which six are known to exist in bats. The best known lyssavirus is rabies. Since November 1996, two Queenslanders have died as a result of ABL following bites or scratches from bats.
Symptoms
ABL is an almost always fatal disease and causes paralysis, delirium and convulsions. Death is often due to respiratory paralysis.
Transmission
Transmission of the virus from bats to humans is thought to be by a scratch or bite, or by being exposed to bat saliva through your eyes, nose or mouth, or through exposure to brain tissue. ABL is unlikely to survive outside the host for more than a few hours, especially in dry environments that are exposed to sunlight. Experience with other closely related viruses, including classical rabies virus, would suggest that contact (such as patting bats) or exposure to bat faeces and urine does not pose a risk of exposure to ABL. Living, playing or walking near bat roosting areas does not pose a risk of exposure to ABL. Direct contact with a bat is necessary.
The time from contact with the virus and the development of symptoms is usually about three to eight weeks, but can be longer.
Treatment
There is no available treatment for ABL. In all possible exposures to ABL (bites, scratches, mucous membrane exposures), seek medical advice immediately even if you have been vaccinated.
Prevention
The best protection against being exposed to the virus is to avoid handling bats. Members of the community should not handle bats or flying foxes. Only vaccinated people who have been trained in the care of bats should ever handle bats or flying foxes. If you come across an injured bat, contact the nearest wildlife rescuer/carer for assistance.
Rabies vaccine is used to protect against ABL infection. Even if vaccinated, every bite, scratch or mucous membrane exposure may infect you with the virus unless the bat is proven not to have ABL.
If bitten or scratched, immediately wash the wound thoroughly with soap and water for at least five minutes. If available, an antiseptic with anti-virus action such as povidone-iodine, iodine tincture, aqueous iodine solution or alcohol (ethanol) should be applied after washing.
If you get bat saliva in your eyes, nose or mouth, you should flush the area thoroughly with water and seek medical advice.
Proper cleansing of the wound is the single most effective measure for reducing transmission. Avoid direct contact with the saliva of bats.
Pre-exposure vaccination
Pre-exposure vaccination is recommended if you are occupationally or recreationally exposed to bats, and there is a risk of being bitten or scratched. This is a course of three rabies vaccine injections, given over one month (days zero, seven and 28). The vaccine is effective but does not offer protection until after the third dose is given.
Post exposure vaccination
For those people who have been exposed to lyssavirus but never received pre-exposure vaccination, an injection of rabies immunoglobulin and a series of five rabies injections will need to be given over one month (on days zero, three, seven, 14 and 30). Queensland Health will fund these injections, which are called 'post-exposure prophylaxis', and your public health unit will arrange for these injections to be delivered to your GP or hospital.
For those who have already received pre-exposure vaccination, two further doses will be required (day zero & three). Queensland Health will also fund these injections.
If possible, without placing other persons at risk of exposure, the bat should be kept and tested by the local public health unit or veterinary authority. The bat should be kept alive if possible as only wildlife authorities, state agricultural departments and authorised veterinarians are permitted to kill bats. Under no circumstances should the bat be deliberately released following potential human exposure to avoid further infections. If the bat does not have ABL, the course of vaccinations will not be required.
Help and Assistance
For further information, please contact your local doctor, community health centre or nearest public health unit.
Other Resources
Footnotes
Heymann, D., ed. 2004. Control of Communicable Diseases Manual, 18th edition. Washington, DC: American Public Health Association. 438-447
National Health and Medical Research Council, 2003. The Australian Immunisation Handbook (8th Ed.) Canberra: National Capital Printing.
Last Updated: 25th July, 2008
Date Valid to: 31st December, 2008
