Introduction
Australian bat lyssavirus (ABL) is a member of the Rhabdoviridae virus family. This particular strain of lyssavirus is closely related to, but is distinct from, the classic rabies virus.
To date, two human deaths from lyssavirus infection have been reported in Queensland, one in 1996 and the second in 1998. Both of these individuals had a history of contact with flying-foxes or microbats, and it is now known that strains of lyssavirus from both types of bats cause disease in humans.

ABL is currently known to infect all four megachiroptera (fruit bats/flying-foxes) in Australia, at least three species of microchiroptera (insectorivorous bat), and humans.
A national surveillance program for ABL is currently in place with on-going blood testing and virus studies in bats indicating that it is widely distributed in Australia.
It is assumed that ALL Australian bats, both the larger flying-foxes and insectorivorus microbats have the potential to transmit the ABL.

Human Exposure
Rabies virus and other lyssaviruses are usually transmitted to humans via bites or scratches, which provide direct access of the virus in saliva to exposed tissue and nerve endings.
Experience with other closely related viruses, including classical rabies virus, would suggest that contact such as patting bats or exposure to urine and faeces does not constitute a risk for exposure to ABL.
Bat blood is not regarded as a high risk tissue for ABL infection. However, it is known that bats carry other microorganisms that cause human disease, and which may be present in blood, urine or faeces.
It is therefore considered advisable for persons to avoid contact with bat excrement or blood whenever possible.

Signs and Symptoms of ABL Infection in Humans
Signs and symptoms of ABL infection resemble those of rabies and include headache, fever, malaise, sensory changes around the site of the bite or scratch, excitability, an aversion to fresh air and water, weakness, delirium, convulsions, and coma. Death, often due to respiratory paralysis, usually follows several days after the onset of symptoms.

How is ABL notified to Queensland Health?
Under the Queensland Public Health Act 2005, any person exposed to ABL is to be immediately notified by telephone to Queensland Health by their doctor.
Queensland Health on notification of an exposure will contact the person to ascertain information on how the person was exposed.

Laboratories are required to immediately notify Queensland Health when testing for ABL in a sample has been requested as well as when the results of any test confirms the presence of ABL in the sample.
All information collected by Queensland Health is maintained on the Notifiable Conditions Systems database (NOCS).
Queensland Health is also required to be notified by officers from the Queensland Parks and Wildlife Services (QPWS) under a protocol developed by these agencies for the collection and transport of potentially infected bats.
When QPWS receive notification of a person who has had a Category 3 exposure with a bat, the local Queensland Health Population Health Unit (PHU) is notified immediately. A Category 3 exposure is defined as a person being bitten or scratched, or where other permucosal or percutaneous exposure to bat saliva or neural tissue has occurred.

What are the statistics?
For the period 1998-2004 Queensland Health Scientific Services (QHSS) received a total of 517 bat specimens for testing for ABL (Table 1).
For this period, more than 99% of all submissions were due to C3 exposures.

Table 1: Number of bats tested for ABL by QHSS, 19982004, by type of bat.

*July-Dec 1998

Notification of potential ABL exposure, 2005-2006
Data for analysis were obtained from the Queensland Notifiable Conditions Systems (NOCS) database for the period 1 July 2005 to 30 June 2006.
All data are collected by regional Population Health Units using a standardised form.
A total of 123 notifications (64 in females and 59 in males) of potential ABL exposure were reported to Queensland Health between 1 July 2005 and 30 June 2006.
Fifty-two bat specimens associated with these notifications were available for ABL testing of which only 1 specimen (flying-fox) tested positive to ABL.
The majority of notifications (60%) involved the flying-fox (Table 3).

Table 2: Number of notifications received by Population Health Units


Table 3: Number of different types of bats responsible for notification


Exposure occurred in the following circumstances:
67% of persons were attempting to rescue the bat (intentional contact);
9% of persons were caring for the bat (intentional contact);
24% of persons had various (unintentional) contact with the bat.
Twenty-nine (23%) notifications involved rescuers trying to extricate the animal from fruit tree netting or barbed wire fencing.
From the data collected the majority of exposures occurred from the bat either biting or scratching the person (refer Table 4).

Table 4: Cause of exposure


What information is out there about ABL?
Queensland and national guidelines/information on ABL have been developed and are located on the Queensland Health; Department of Primary Industries & Fisheries; and Commonwealth Department of Health and Ageing websites.

Cover illustration by Louise Saunders