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Bat lyssavirus |
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Table of Contents
Bat Lyssavirus
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Information for medical practioners
Recommendations of the Lyssavirus Expert Group Meeting 11 November 1996,
endorsed by the Communicable Diseases Network Australia New Zealand.
This information provides a background to the newly identified bat Lyssavirus
and recommendations for dealing with patients who have been in contact with
bats.
Background
A new Lyssavirus has been identified during 1996 in two species of bats
in Australia. The two species are the Black Flying Fox (Pteropus alecto)
and the Little red Flying Fox (Pteropus scapulatus). In November 1996, a
woman in Queensland developed encephalitis, probably due to the virus, after
being bitten and scratched by bats.
The genus Lyssavirus falls within the family Rhabdoviridae. There were six
genotypes recognised within the genus. These include the classic rabies
virus, Lagos bat virus, Mokola virus, Duvenhage virus and the two European
bat lyssaviruses. These viruses have not previously been reported to occur
in Australia. The newly identified seventh Lyssavirus is closely related
to, but is distinct from, the classic rabies virus. In laboratory animals,
rabies vaccine and rabies immunoglobulin are protective against this new
Lyssavirus.
Non-rabies Lyssaviruses usually do not spread among terrestrial animals
and human infections are rare. The newly identified Lyssavirus is currently
known to infect fruit bats (flying foxes) and humans. Insectivorous bats
are known to carry other Lyssaviruses overseas and therefore cannot be discounted
as a potenital risk, at this stage.
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. This means that most people would not
be exposed to Lyssavirus through casual contact with bats.
As the bat Lyssavirus is closely related to classic rabies virus, infection
may be prevented by rabies vaccine and rabies immunoglobulin. Recommendations
for administering theses are provided below. Further research is being conducted
into the distribution and transmissibility of the virus. Recommendations
may be updated as more information becomes available.
Recommendations
Pre-Exposure Vaccination
Preexposure vaccination should be recommended to those occupationally or
recreational exposed to bats, where there is a risk of being bitten or scratched,
for example
- Bat carers
- Veterinarians
- Wildlife Officers (including local government officers)
- Veterinary laboratory staff
- Managers of display or research colonies
- members of indigenous communities who may catch bats for consumption
- Power lion workers who frequently remove bats from power lines.
Pre-exposure vaccination consists of three intramuscular doses of 1ml rabies
vaccine given on days 0, 7 &28. Doses should be given 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.
Persons bitten or scratched by bats.
The wound should be scrubbed thoroughly as soon as possible with soap and
water. Proper cleansing of the wound is the single most effective measure
fro reducing thee transmission. Where possible, the bat should be kept for
further investigation by the State veterinary laboratory.
Guidelines have been developed to aid the decision on whether to administer
vaccine alone or combined with rabies immunoglobulin. Factors include the
type of wound, how recent the exposure was and the behaviour of the bat.
Please contact your public health authority who will provide advice on the
appropriate course of action.
Contact such as patting bats or exposure to urine or faeces does not constitute
an at risk exposure. Pre-exposure vaccination should be offered if the person
has on-going contact with bats.
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