Virulent virus carried by wind

The virus that causes foot-and-mouth disease is a tough customer. It survives pasteurisation and can live outside its host for up to a month, awaiting a fresh chance to cause infection.

"In terms of transmissibility, it is one of the most contagious," said Prof P.J. Quinn, professor of veterinary microbiology and parasitology in the faculty of veterinary medicine at University College Dublin. "Pasteurisation does not kill the virus," and it can survive temperatures up to 95 degrees for 30 minutes. It is also "quite stable", surviving in cool winter air in fodder, or an uncleaned lorry for up to a month. Even in summer it will survive for a week outside its host.

Durability enables the virus to be carried on the wind over 100 kilometres or more. Infection could travel the 100 kilometres between Wales and Ireland but it was unlikely, Prof Quinn said, because the prevailing wind would carry the virus east towards England. Infection was more likely to reach us via dirty boots, on a truck or in meat or dairy products carrying the virus.

The organism is an aphthovirus and its family is Picorna viridae. There are dozens of subtypes, some more virulent than others. Reports have suggested this outbreak is a virulent Asia 1 or O serotype. It affects cattle, pigs, goats, sheep and deer but not other animals such as dogs, cats or horses. Infection is caused from inhaling or eating virus particles - only a small amount is needed. to

The infection causes blisters and ulcers in the mouth and on the feet but does not usually kill the animal. "The only alternative in this part of the world is slaughter," Prof Quinn said. The disease very seldom has any effect on humans.

The virus resists many disinfectants but is "very susceptible" to a change in acidity. Acid or alkali conditions kill the virus, so weak citric acid solution and washing soda, sodium carbonate, are often used to disinfect shoes, boots and vehicles transporting animals.