Wednesday, December 2, 1998 Published at 19:06 GMT
Bat disease threat down under
Bats can pass on diseases to humans
The deadly virus rabies could return to Australia through a new infection carried by bats.
The Australian bat lyssavirus (ABL), first isolated in May 1996, belongs to the same family of viruses as rabies - a disease that kills up to 100,000 people a year, mainly in developing countries.
Scientists say it is the virus most closely related to rabies, differing by only 8%.
By October 1996, ABL had claimed its first human victim - a woman from Queensland who had been looking after sick and orphaned bats.
Fred Murphy, a world expert on viral diseases at the University of California, told New Scientist magazine that, as far as he is concerned, the woman died of rabies.
Experts in Australia believe the virus could cause a disease which is more or less the same as rabies.
The Australian Animal Health Laboratory has just started research to find whether cats and dogs can be infected with the virus.
Experts think this is likely. If they are also found to pass on the virus in their faeces, there may be important implications for human health.
However, the rabies vaccine appears to work on the new virus so bat handlers are being advised to take it.
Two other bat-related viruses have emerged in Australia in recent years.
Both are capable of infecting humans, according to New Scientist.
Bats are common in Australia, particularly the large fruit bats which cover two thirds of the country.
As their natural habitat is being destroyed by man, the bats are moving closer to urban areas.
Colonies have been found in botanic gardens outside Melbourne and Sydney.
Chris Tidemann, an ecologist at the Australian National University in Canberra, says some women have been known to feed their breast milk to orphaned bats.
He says they do not understand that diseases can be passed from bats to humans.
One of the new viruses was first identified in thoroughbred horses in a Brisbane suburb.
The horses came down with a respiratory disease in 1994 and 13 died. So did their trainer, Vic Rail.
They called it megamyxovirus. A year later, a sugar cane farmer in northern Australia developed severe muscular seizures and died.
He was found to have been infected by a horse with the virus a year earlier.
It is thought that the horses may have caught the virus from the uterus fluid from female bats which had just given birth.
Experts believe the fluid may have dropped onto the ground from the trees where the bats were nesting and entered into the horses' bloodstream after they ate or licked it.
It may then have passed to the farmer through cuts on his arms.
Other new bat viruses which may infect humans include paramyxous virus, which causes flu-like symptoms; Ross River fever, a virus carried by mosquitoes; and Japanese encephalitis, a potentially fatal brain infection.
However, experts caution against a panic reaction to bats since only a small number of humans have become infected by the new viruses.
Also, most bats eat mosquitoes and therefore help to prevent the transmission of diseases carried by these insects, such as malaria.