Two years ago, on a remote island off the coast of South Australia, government scientists began testing a form of biological warfare. Under supposedly tight quarantine restrictions, researchers on Wardang Island introduced the calicivirus into animal test groups. Death from this particular infectious agent is swift. As the blood of the victims begins to clot, restricting the brain's oxygen supply, they become lethargic; within 30 hours they are dead from acute respiratory and heart failure.
No one paid much attention to these pestilent experiments until this year, when they suddenly got out of hand. By October researchers realized that the virus had escaped from the test sites and spread throughout the 30-sq-km island. As scientists tried in vain to contain the outbreak, their worst fears were soon realized: casualties began to appear on the mainland. But even as the death count surged into the millions and the disease reached as far as the Flinders Ranges 800 km away, Australians didn't panic. In fact, many cheered, since the victims of the plague were old enemies, the country's vexatious rabbits.
For most Australians, the benign image of the rabbit conveyed by Peter Rabbit simply doesn't apply. Ever since a landowner imported and released 12 wild rabbits in 1859, they have multiplied into a ravenous horde that nibbles away at the nation's crops and agricultural profits. Planning for systematic extermination programs began in the 1940's, when an estimated 1 billion rabbits were devouring produce, causing land erosion and destroying native habitats. Government scientists introduced myxomatosis, an anti-rabbit virus from Brazil, in 1950.Though the campaign reduced the rabbit population to 100 million within two years, the survivors later built up immunity and restocked their numbers.
In 1984, a virus that began sweeping through China's rabbit population gave Australians new hope. Harmless to humans, rabbit calicivirus disease (RCD) was introduced to Europe in the '80s, probably via smuggled rabbit products, and has helped bring rabbit populations down to tolerable levels. Impressed by the well-documented results, Australia's Commonwealth Scientific and Industrial Research Organisation imported a batch of the virus from the Czech Republic in 1991. After three years of safety tests, they set up the experimental station on Wardang Island for field trials.
Tests convinced the CSIRO that the virus posed no threat to other Australian animal species or to humans, so plans had been made to release RCD at seven sites on the mainland in February 1998, following further research and a period of public debate.
Then came the outbreak. So far an estimated 5 million rabbits have died, and the epidemic continues to move north and east. Few people would miss the $500 million in damage the rabbits cause each year, but in the aftermath of the Ebola scare in Africa, the ease with which the calicivirus eluded its human handlers has raised some troubling issues. Embarrassed CSIRO scientists believe the disease was spread by bush flies that came into contact with the infected rabbits and were then blown onto the mainland by freak winds. The government has imported 100,000 doses of Cylap vaccine to save pet and laboratory rabbits, and the CSIRO is trying to persuade the public that no damage to the environment or human health will result from the virus' premature release.
Environmentalists have also voiced concern that a sudden disappearance of rabbits could have unfortunate effects on the wildlife food chain. One possibility is that foxes and feral cats, which depend on rabbits for food, could instead turn to small native fauna, some of which are endangered species.
For the moment at least, fanners are overjoyed about the killer virus. "This is the most exciting development for the Australian environment in years," says David Lord, a fourth-generation farmer, whose 66,000-hectare spread near Broken IIill has some 750,000 unwelcome guests.
