A man from northern New South Wales has died after contracting the state’s first recorded case of Australian bat lyssavirus, a close relative of the rabies virus.
The man, in his 50s, was bitten by a bat “several” months ago and received treatment at the time, NSW Health said.
On Thursday, the department confirmed the man had died and urged the community to avoid touching or handling bats.
What is Australian bat lyssavirus and where did it come from?
Australian bat lyssavirus is an extremely rare type of lyssavirus, of which rabies is also a type. It was first identified in May 1996 in a fruit bat in northern NSW, according to a paper written shortly afterwards, and is Australia’s only lyssavirus.
The virus has been found in species of flying foxes, fruit bats and insect-eating micro-bats in Australia – and any bat in Australia could carry the virus, NSW Health said.
Prof Tim Mahony, a research fellow in veterinary biology at the University of Queensland, said fatal cases in humans were down to a “very rare convergence of different factors”.
“We’ve had four cases since we’ve known about it in the mid-1990s. Over that time, I would expect thousands of people have been exposed to bats in some way or another,” he said.
How do humans contract it?
Humans contract the virus when bitten or scratched by a bat.
Animals can be infected and the virus appears to have a broad host range, Mahony said. Transmission from an infected pet to a human is theoretically possible, according to a 2018 study, but highly unlikely.
Wildlife disease ecologist at the University of Sydney, Dr Alison Peel, said bats carried the virus in their saliva and could pass it on if saliva came into contact with an existing wound.
It isn’t enough to simply be near bats or exposed to their faeces, she stressed.
“Person-to-person transmission of lyssavirus has only been reported in people who have received infected tissue or organ transplants”, NSW Health said.
Have there been other cases in Australia?
The first human case of the virus was identified in a Queensland wildlife carer in October 1996, according to a separate 2018 study. A second fatal human case, 27 months after a bite from a flying fox, emerged in December 1998.
A young boy died in 2012 after “unsolicited” contact with a bat, then two cases of the virus were found in horses in 2013.
Peel said contracting the virus, even among animals, was “very rare”.
“There have been some studies that have screened thousands of healthy bats and failed to find the virus in any of those,” she said.
“We think it is circulating probably at less than 0.5% of the [bat] population at any given time.”
However, while infection in wild bats is low, “the significantly higher infection prevalence in rescued sick and injured bats represents a clear and present public health danger because of the higher risk of human exposure”, research suggests.
How is it treated?
There is no effective treatment for lyssavirus once symptoms have presented, according to NSW Health. Symptoms include fever and loss of consciousness.
Once humans become infected, the virus travels slowly through nerves towards the brain, Peel said.
“That takes a long time, and it is variable from person to person and where the bite site is, but it is only once the virus reaches your brain that you start to demonstrate clinical signs from the infection.”
Is there a vaccine for it?
The rabies vaccine works as effective immunisation against Australian bat lyssavirus.
For people at increased risk of coming into contact with bats including vets, animal carers and power line workers – who often relocate bats from lines – NSW Health recommends three injections given over the course of one month.
What should people do if they’re bitten or scratched by a bat?
Wash the wound thoroughly for 15 minutes with soap and water, apply an antiseptic with anti-virus action, such as betadine, and allow it to dry, NSW Health advises. Patients then need to be treated with rabies immunoglobulin and the rabies vaccine.
Mahony said the vaccine would be given as a prophylactic. A lot of injections given over a short period of time, he said, would “get the immune system working as quickly as possible”.
Because the virus has a long incubation period – usually of up to a few months “for reasons we don’t understand”, said Mahony – preventive treatments given quickly can be highly effective.
How can people avoid being bitten?
Avoid handling bats and do not attempt to rescue an injured or distressed bat.
Mahony said it would be very unusual for a member of the public to come into direct contact with a healthy fruit bat.
However, while bats are famous for carrying a range of viruses that don’t tend to affect them, Australian bat lyssavirus can make them sick. If they are on the ground – even if injured – it’s best to assume a bat is carrying the virus.
“If people don’t know what they’re doing, just don’t handle them at all,” he said.
Only wildlife handlers who are trained, protected and vaccinated should interact with bats, NSW Health said.
