Foot and mouth is a highly infectious disease affecting mostly sheep, pigs and cattle in which fever is followed by the development of blisters, chiefly in the mouth or on the feet.

The disease is rarely fatal, except in very young animals, but does cause lameness and reduced milk yields.

The interval between exposure to infection and the appearance of symptoms usually varies between 24 hours and 10 days, but can be longer. The average is three to six days.

It is very rare in humans and even then is mild, short-lived illness requiring no medical treatment.

Animals generally pick up the virus either by direct contact with an infected animal or by contact with feed that has been infected by such an animal. The virus can also spread on the wind, on boots and clothing or on trucks used for animal transport. It can even be picked up and carried on the wheels of passing vehicles. Dogs and cats, poultry, wild game and vermin can also transmit the infection.

TREATMENT

Culling remains the basic control policy used to stop the spread of the virus. Vaccination is possible, but it can also conceal the presence of the virus in an animal. For this reason, many countries ban the import of vaccinated livestock, making vaccination unpopular with many farmers.

Heat, sunlight and disinfectants will destroy the virus, whereas cold and darkness tend to keep it alive.

SYMPTOMS

Signs of the disease in cattle: excess salivating, shivering, reduced milk yield, sores and blisters on feet, raised temperature

Signs in sheep: sudden, severe lameness, reluctance to move, blisters around feet, blisters in the mouth Signs in pigs: sudden lameness, prefers to lie down, blisters around the feet, blisters on the snout or the tongue

2001 OUTBREAK

An outbreak in 2001 was the largest in Britain since proper records began. There were 2,030 cases spread across the country.

More than six million animals were culled, of which almost five million were sheep. Many were burnt on funeral pyres.

A ban on livestock and meat exports was estimated at the time to be costing the industry 8 million pounds ($16 million) a week.

ECONOMIC IMPACT

The value of British sheep, beef and pig exports (live animals and meat) was more than 500 million pounds in 2006.