Myxomatosis was originally transported from Brazil (where it was first discovered in the 1930's) to Australia in 1950. This disease was used to control increasing populations of rabbits in that subcontinent. Although in Brazil Cotton Tailed Rabbits were only slightly affected by this virus; in Australia it was devastating and markedly reduced populations. Once this was noted, a French Doctor wanting to control the rabbit population on his estate near Paris bought the disease to Europe , which vastly spread through the wild rabbit population and eventually was accidentally bought to the UK in 1953.
Myxomatosis is caused by the pox virus which has proven to grow well in rabbit skin.
The virus is spread by insect parasites and in the UK this is the rabbit flea. It is also thought to be transmitted by mosquitoes, however, this is yet to be proven.
Incidentally, myxomatosis is not easily spread by simple contact from one rabbit to another. The virus however, does remain active in the blood of fleas for many months and it is probably by over-wintering of fleas in rabbit burrows that the disease is transmitted from year to year.
The Infection Process
A flea will bite a susceptible rabbit. As it bites a small amount of the live virus is placed under the skin whilst the insect draws blood.
Within a few days the virus is transmitted to local lymph nodes and then passes into the blood which allows it to be moved around several sites.
The virus mainly multiplies in the skin around the eyes, the nose , inside the ears, around the anus and genitals.
Initial symptoms of myxomatosis are puffy swellings around the head and face. "Sleepy eyes" are classic signs alongside swollen lips. Additional swellings will appear around all the sites formerly mentioned in regards to how the virus multiplies in the organism.
In 24 hours, swellings may become so severe as to cause blindness.
Factors such as inflammation of the face and other sites causing discomfort will naturally suppress the animals appetite, possibly leading to anorexia.
Usually fatal. Common cause of death is secondary lung infection which often occurs 8 days post initial incubation of the virus.
Flea control is extremely important. Wild animals and cats must be kept away from pet rabbits as they may be secondary transmitters of fleas. Bedding must be regularly cleaned and kept dry.
Vaccinations offer the best possible protection against myxomatosis. The vaccine used is NobivacR Myxo. This utilises a virus called the Shope Fibroma Virus but does not cause disease.
A single vaccination should be given to any rabbit over 6 weeks of age and then booster vaccinations are advised every 6 months.
Immunity is established 14 days post initial vaccination. The animal should not be exposed to infection during this 2 week period.