New Australian virus infects people

From Atlanta, at the International Conference on Emerging Infectious Diseases

Yet another virus carried by fruit bats has been found to cause human illness. After the discoveries of Hendra virus and Nipah virus in recent years, scientists in Australia have identified a virus that devastates pigs’ reproductive capacity and has caused illness in at least two people.

Both Hendra and Nipah viruses, members of the family Paramyxoviridae, have been linked to fruit bats in southeast Asia and Australia. The new virus, also a paramyxovirus, has been dubbed Menangle virus. It was discovered after hundreds of sows on a large swine farm near Menangle, New South Wales began having fewer litters, fewer piglets per litter, and deformed or aborted young, reports Peter D. Kirkland, a virologist and veterinarian at the Elizabeth Macarthur Agricultural Institute in Menangle.

After making inquiries, Kirkland and his colleagues found out that two men who had worked with the pigs had been sick for 2 weeks with severe flulike symptoms. Antibodies in their blood matched those taken from infected sows, Kirkland says. The men recovered.

A colony of gray-headed fruit bats roosts near the pig farm. Tests on blood taken from the bats a year before the disease hit the pig farm showed the bats had the virus. They continued to carry it during the period when the pigs were stricken. Tests on birds, mice, rats, a dog, and other animals proved negative.

The virus didn’t harm adult pigs, which might have acquired it from food tainted with bat droppings. In sows, “it crossed the placental barrier and directly infected the fetus,” Kirkland says.

The pig operation was quarantined, and the infection hasn’t spread to the rest of Australia’s swine industry. As adult pigs overcame the virus, workers moved them to clean quarters and gradually disinfected the entire operation, Kirkland says.

The means of viral spread from pigs to people is unknown, although mere contact isn’t likely enough to transfer it, he says. The researchers tested 600 people who had contact with infected pigs, including workers at a slaughterhouse, but none tested positive except the two farm workers.

As with many viruses, “you really don’t know when something jumps from one species to another,” Kirkland says. “But once it becomes adapted to that [new] species, it could potentially spread better” and pose a greater risk to people, he says.

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