"The myxoma virus is an introduced disease. Its first field release was at Gunbower (Victoria) in 1950, where it killed more than 90 percent of rabbits. The initial spread of the virus saw rabbit numbers reduced from 600 million to 200 million. But the virus has mutated in some less lethal strains, and rabbits have developed greater immunity through natural selection. The ability to survive myxomatosis has been passed on to offspring by survivors.

The virus is transmitted via mosquitoes and fleas and causes a prolonged inhumane death. It begins to multiply in the rabbit’s outer and inner layers of skin, often causing an ugly bump like a tumour. By the second day it has spread to the lymph glands and by the fourth day is in the body tissues. By the fifth day, eyes, genitals and anus start to swell. This swelling may be severe enough to rupture the male rabbit’s scrotum. Over the next three days, more bumps appear over the body. A rabbit infected with the most virulent strain is usually dead by the tenth day. But if the strain is not so lethal, or if the rabbit has some immunity, it can live for three weeks. The eyes are closed, the ears hang, pus pours from the nose and the breathing is laboured."

Rabbit Calicivirus Disease (RCD) formally known as Rabbit Haemorrhagic Disease (RHD) -- RCD is a disease in rabbits resulting from infection by the rabbit calicivirus. As the disease does not actually cause haemorrhaging in rabbits, scientists have recently agreed that it should be renamed Rabbit Calici Disease (RCD). The virus first appeared in 1984 among farmed rabbits in China. It has since spread through farms in Europe, killing 64 million rabbits in 1986 in Italy alone. It has now appeared in 40 countries on four continents, and has spread to wild rabbits, which as a result may disappear completely from some parts of Europe.

The virus was imported into Australian 1991 for intensive research at the CSIRO Australian Animal Health Laboratory (funded by Australia and New Zealand) to decide whether the disease should be released into wild rabbit populations.

Scientists say that it is harmless to stock, native mammals and hares. RCD-infected rabbits die in 30-40 hours. Rabbits under 8 weeks old are not killed by it. It attacks the livers and spleens, and although overseas scientists have reported a ‘low level of observable distress’ in infected rabbits, no distress has been observed in laboratory studies in Australia.