Australian scientists are testing a vaccine to fight two deadly animal viruses that can infect and kill humans. Scientists say one of the pathogens, the Nipah virus, is considered a potential biological weapon. It killed more than 100 people and a million pigs in Malaysia in 1999, while the Hendra virus killed two Australians in 1994.

Both viruses are carried by fruit bats and have alarmed scientists by the ease with which they jump from animals to humans. Scientists from the Commonwealth Scientific and Industrial Research Organization (CSIRO) said that testing of a new vaccine showed promise of preventing both diseases.

The World Health Organization says that although the risk of transmission of the Nipah virus from animals to humans is  low, it is a growing health risk to people.