Myxomatosis is a viral infection which is fatal to rabbits, although it is treatable in tame rabbits if caught early enough, and it was first reported in Uruguay, South America, in 1898. Attempts to use it as a means of controlling wild rabbits have resulted in epidemics. It can be transmitted by any biting or blood-sucking insect, such as a flea or a mosquito.

Insect vectors form a very important method of transmission. A wide number of mosquitoes, fleas, ticks, mites and lice have been shown to be vectors. The insects can feed on the blood of the infected rabbit or more easily on the exposed area of skin lesions. Further more, unlike infected rabbits which die after about ten days after which the possibility of contact infection is reduced, it has been shown that mosquitoes can carry a virus capable of re-infecting rabbits for up to 6 weeks. Rabbit fleas, particularly Spilopsyllus cuniculi, can act a reservoir of infection for several months after rabbits have deserted a burrow.

Taking into account the range of mosquitoes this allows transmission of the myxoma virus over greater areas than are usually travelled by the rabbits alone. This allows the spread of the virus to take place between colonies of rabbits, and in the case of the fleas, allows rabbits from a different colony to become infected be entering a warren where all the occupants have been killed by myxomatosis some months previously.

The symptoms of myxomatosis include a watery discharge from the eyes and swelling of the eyelids and nose. Death follows in about two weeks. Since 1952, it has been illegal to spread the disease in Britain by the use of infected animals. Nevertheless, an epidemic broke out in Britain in 1953. It has been estimated that 99% of the rabbit population of over 60 million died in this epidemic.

Apart from killing off large numbers of the rabbit population, myxomatosis had an indirect effect on the rabbit's predators. The buzzard population in particular suffered a serious setback. Grass on downlands quickly became long since there were fewer rabbits, and attacks by foxes on hen roosts and game became more frequent. The disease is still liable to flare up in some areas, although there are indications that many rabbits are now immune.



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