Determining if a bat or other animal was infectious by clinical observation

This is a short, easy-reference guide about how to assess whether a bat (or other animal) could have infected another animal or person at a particular time. Consult the complete document, ABLV – Information for veterinarians, for more comprehensive information about managing the risk of Australian bat lyssavirus (ABLV) in animals.

You should only use clinical observation to determine if a bat was infectious for Australian bat lyssavirus (ABLV) when it is reasonable under the circumstances. A bat showing progressive clinical signs clearly suggestive of Australian bat lyssavirus, should be euthanased and tested for animal welfare reasons and to inform risk assessment.

Conditions for clinical observation

Clinical observation allows you to assess the likelihood that a bat was infectious at a particular point in time (for example, at the time of a potentially infectious contact). It may be reasonable to make this assessment clinically (rather than via laboratory testing) if:

  • there are no clinical or behavioural signs clearly suggesting ABLV
  • the carer is rabies-vaccinated and experienced in handling bats safely (avoiding bites and scratches)
  • the carer agrees to:
    • use appropriate personal protective equipment when in contact with the bat
    • hold the bat in a separate enclosure (no direct contact with other bats or animals) for 10 days post-contact
    • contact the veterinarian urgently (as soon as reasonable, and at least within 24 hours) if the bat becomes unwell, dies or warrants euthanasia
    • support euthanasia and testing of the bat if the veterinarian decides the bat is clinically consistent with ABLV
    • contact the veterinarian to report the bat's clinical status 10 days post-contact.
  • the carer is aware of their general biosecurity obligation in relation to bats and ABLV.

Interpreting the outcome of observation

If the bat survives for 10 days post-contact

If the bat survives for 10 days after contact without showing clinical signs suggesting ABLV, you can reasonably assume that the bat was not infectious at the time of contact and didn't transmit ABLV to other animal(s).

The bat, and all animals that had potential contact with the bat, may be released to normal care or rehabilitation. The bat may be released to the wild once adequately rehabilitated.

If other animals had received a vaccination pending the outcome of observation, the second vaccination (Day 7PV) is not necessary. You may discontinue the vaccination protocol.

Note: If the bat survives to Day 10 post-contact, it doesn't mean the bat was not infected (subclinically) at the time of contact, but it does mean that the bat was not infectious at the time of contact. A bat incubating ABLV may progress to clinical disease and become infectious in the following months or years but wouldn't have been infectious months or years earlier.

If the bat dies within 10 days of contact

If the bat dies, or is euthanased, within 10 days of contact and laboratory tests show the bat was ABLV-infected, or if tests do not exclude ABLV, you should:

  • assume the bat was infectious at the time of contact
  • consider any in-contact person or animal as exposed and potentially infected.

Your response may include advising the owner to initiate or complete the post-exposure vaccination protocol.

Also consider...