Flying Foxes and the Virus Story

We all know how highly contagious viruses can be. Colds and flu sweep through the world wide human population seasonally, transmitted merely by a cough or a sneeze. However, our companion animals, cats and dogs do not catch these viruses from us and we do not catch canine distemper or feline enteritis from them. Fortunately, many viruses in animals are species specific. They infect only a proportion of the host animal population, but do not transmit to humans or other species. However, occasionally, a virus does cross the species barrier and the results can be devastating, as in the case of AIDS from apes to man or distemper from husky dogs to seals, (in the great seal epidemic of 1988).

When Vic Rail, horse trainer at the Cannon Hill stables, Brisbane died in September 1994 from a mystery disease, along with several horses from the same stables, quarantine restrictions were immediately put into place and Australia’s horse-racing industry came to a standstill. This outbreak, which could have been one of a number of feared exotic horse diseases seemed to emerge from nowhere. The infection was found to be a virus previously unknown in horses or any other species. Potentially, this virus could have spread throughout both the horse and human populations with disastrous consequences. Fortunately, however, the virus proved not to be highly contagious and no more fatalities occurred at that location, although another human fatality did occur at Mackay, one year later.

This new virus, named Equine Morbillivirus (EMV) or Acute Equine Respiratory Syndrome wrecked havoc on animal tissue and was as deadly as the Ebola virus from Africa. EMV attacks the lining of the blood vessels in the lungs. The affected horse’s lungs fill with blood, resulting in a frothy nasal discharge. In humans, a latent encephalitis may also develop, as well as pneumonitis. This was not a disease to be ignored. Its source had to be found before further spread of the disease occurred in the horse and human population or in any other species it may be able to infect.

Australian virus researchers were mobilized and so began what is probably one of the most remarkable virus hunts ever recorded in the history of Australia. The research into the new virus not only revealed the nature of this new deadly horse virus, but inadvertently lead to the discovery of yet another new and deadly virus, a lyssavirus, which was found to be a close relative of the rabies virus. Research into the source of these two deadly viruses has linked them directly or indirectly to viruses carried by flying foxes. Tragically, a bat carer died from this new lyssavirus in 1996. The discovery of these potentially fatal viruses in bats has dealt a blow to flying fox lovers.

People were made aware of the new bat viruses through media coverage (sometimes sensational) by the press and television. Nobody seemed to care that you could catch a deadly virus from a horse, but to catch a deadly virus from a bat, that was another matter! The tabloid shocked us with headlines such as “Killer bat bites two” and “Virus alert after mad bat attack”. The main challenge of scientists and lay people alike is to get the issues into perspective.

To simplify the presentation of the large amount of information on these bat viruses, the data in the 1997 issue of the Friends of the Far North Flying Foxes Newsletter was divided into outlined subject boxes. The large amount of space taken up in this newsletter by the virus issues reflects the seriousness of these new viruses to bat handlers.

All bat handlers should take precautions when handling sick or injured flying foxes or bats of any kind. Bat handlers, carers, foster parents and researchers should be vaccinated with the rabies vaccine to provide protection against the bat lyssavirus.

However, in the case of the EMV virus (bat paramyxovirus) no vaccination or post exposure treatment is available!

Information provided by Ann Johnson
Friends of the Far North Flying Foxes