It was introduced by accident in the 1950's. It became illegal in 1954 to release infected rabbits into the countryside apparently. I found this blog from last year. It is written by a pest control officer.
"I have had several rabbit jobs recently where the rabbits had been causing havoc in client's gardens eating newly sprouting plants and excavating holes in carefully tended lawns. I've had quite good results with cage traps set in the feeding areas and Fenn Mk6 traps set in the burrows. This happy state of affairs, for me at least, is soon going to end locally as I've seen several dead & dying rabbits while I've been out with the dog in the last week or so. Indeed only this morning the dog pounced glee fully on an infected rabbit, proudly retrieved it and then looked at me in disbelief as I threw it on top of the hedge for the buzzards, after having put it out of it's misery.
And a miserable, pitiful end it surely is, rabbits with myxomatosis suffer from swellings to the connective tissue around the eyelids, nose and genital regions. Their eyes often swell up so much that they can't see in the later stages of the disease and they lose their way from the burrows allowing them to fall prey to any passing predator.
Myxomatosis first reared its ugly head in Britain in 1953 after a French doctor carried out experiments on his estate in France and infected rabbits escaped. There were initial attempts to stamp the disease out but it soon spread countrywide on its own and with artificial help from landowners releasing infected rabbits (a practice which was made an offence in 1954). The initial outbreak in the 50's killed an estimated 99% of several hundred million rabbits within two years and changed the face of the British countryside forever.
The virus seems to come around every 2 or 3 years and depending on its strength or the rabbit population at the time, it has varying impacts on rabbit numbers, sometimes almost total wipe out, other times the rabbits recovering quite quickly.... and rabbits being rabbits, they are soon back up to good numbers. The disease is spread in Britain by the fleas which infest the rabbits and their burrows, passing the virus from rabbit to rabbit in the close confines of the warren. From infection it takes fully susceptible rabbits 11 to 18 days to die from the most virulent strain, however some rabbits always seem to survive an outbreak and these can pass immunity on to
their young.... I hope there are a few that make it through this time & the numbers are soon back up to the levels where they need control ( if not some ferrets might be facing redundancy)."
Taz x