Myxomatosis is a disease which infects only rabbits. It is caused by the myxoma virus. First observed in Uruguay in the early 1900s, it was deliberately introduced into Australia in an attempt to control rabbit infestation there—see rabbit (ecology).
At first, the disease is visible by lumps and puffyness around the head and genitals. This may progress to acute conjunctivitis and possibly blindness. The rabbit becomes listless, loses appetite, and develops a fever. In typical cases where the rabbit has no resistance, death takes an average of 13 days.
After its discovery in imported rabbits in Uruguay, a relatively harmless strain spread quickly throughout the wild population in South America. In Australia, the virus was first field-tested for population control in 1938. A full-scale release was performed in 1950. It was devastatingly effective, reducing the estimated rabbit population from 600 million to 100 million in two years. However, the rabbits remaining alive were those least affected by the disease. Genetic resistance to myxomatosis was observed soon after the first release and most rabbits acquired partial immunity in the first two decades. Resistance has been increasing slowly since the 1970s, and the disease now only kills about 50% of infected rabbits. In an attempt to increase that number, a second virus (rabbit calicivirus) was introduced into the rabbit population in 1996.
A vaccine is available for pet rabbits, but is illegal in Australia. Myxomatosis is spread by fleas and mosquitos, so attempt to keep pet rabbits away from these pests.
