Virulent new strain sweeps the world

Tracing the virus

The Type O strain of foot-and-mouth disease involved in the new British outbreak is the most virulent mutation of the virus yet known.

The Type O strain of foot-and-mouth disease involved in the new British outbreak is the most virulent mutation of the virus yet known.

First identified in India in 1990, it has penetrated countries untouched by the disease for decades. Last year it appeared in Japan, South Africa, South Korea, Mongolia and Russia. Its arrival in the UK belies the belief that foot-and-mouth had been eradicated in Western Europe.

In South Africa, infected pig swill traced to a consignment of food waste illegally offloaded from an Asian boat into Durban harbour was thought responsible. In Japan, which had recorded no outbreak since 1908, the suspect was hay and silage imported from China and contaminated with infected faeces, urine or saliva. In the South Korean case, Chinese dust storms were suspected. But what are the likely scenarios in Britain?

One of the world's most contagious diseases, foot-and-mouth disease can not only pass from animal to animal at destructive speed; it can also travel by air, with the virus crossing distances of 150 miles or more.

But while airborne transmission was responsible for the last recorded case of foot-and-mouth in Britain in the Isle of Wight in 1981, when a partially inactivated foot-and-mouth vaccine passed across the Channel from Brittany, such a repetition is impossible this time, experts say, because there have been no cases nearby for years.

Experts have also all but dismissed the legal import of diseased carcasses or processed meat as the origin. Since the infamous British outbreak in 1967-68, when frozen Argentinian lamb carcasses were responsible, import regulations have been tightened up immeasurably.

Meat may no longer be legally imported from countries where the disease is known to be present, and meat imports must be stripped of the bone and glandular tissue that can harbour foot-and-mouth after an animal's death.

According to Dr Andrew James, director of the veterinary epidemiology unit at the University of Reading, "the possibility of importing foot-and-mouth disease as part of the regulated meat trade is extremely unlikely. It would be amazing if the virus got through these levels of controls."

One real possibility is that the infection was brought into the country on the shirt collar, hat or shoes of a member of the public.

"Someone could have brought in the contaminated material. They could have been visiting a farm with contamination abroad and be carrying it on their boots, clothing or even under their fingernails," said Dr Paul Kitching, head of exotic disease research at the Institute of Animal Health in Pirbright, Surrey, the global reference library for foot-and-mouth and the institute which has been leading the scientific investigation into the new British epidemic.

And though the thought that something like a pork sandwich imported into the country illegally may be behind Britain's foot-and-mouth crisis appears far-fetched, that is precisely what leading scientists and veterinary officers are seriously now suggesting.

Experts investigating the outbreak of classical swine fever in East Anglia last year strongly suspect that it was caused by diseased meat discarded on a public footpath adjacent to a Norfolk pig-breeding centre.

British customs seize suitcase after suitcase of illegally imported meat each year at air and sea ports: bags full of cheap meat, home-made sausages or even entire animals.

"People bring it with them on the plane. There are examples of whole deer confiscated that they shot abroad, cut up and bagged up," said Nick Allen, regional manager of the Meat and Livestock Commission.

Such food could also harbour foot-and-mouth disease for a surprisingly long period. While its incubation period in pigs is short (two to 14 days), given the right temperature and conditions it could survive for months.

The other major possibility is infected pig swill, as in the recent South African case. Much has been made of the fact that Burnside Farm, at Heddon-on-the-Wall, Northumberland, which is thought to be the source of the outbreak, was licensed to use pig swill.

Pig swill, or processed waste vegetable and meat matter, is used increasingly rarely by farmers in Britain today and must be heated to high temperatures to kill off any disease. Farms using pig swill are also subject to regular inspection by veterinary officers.

Speaking yesterday, the Government's chief veterinary officer, Jim Scudamore, said that the pig swill was supplied to Burnside Farm from another farm in the region, and that "over the years, there had been a lot of visits [to Burnside Farm] and there had been no problems with the pig swill licence".

Even if the Ministry of Agriculture, Fisheries and Food (Maff) gets to the bottom of the latest outbreak, many people will ask why a truck-load of FMD-infected pigs from a Northumberland fattening farm should be transported the length of the A1 to an abattoir in Essex, its cargo breathing, salivating and excreting infected material the whole journey long.

In the view of Mr Allen, the massive rationalisation and reduction in the number of abattoirs in the UK in recent years is to blame.

The Brentwood abattoir in Essex where foot-and-mouth was first identified is one of only a handful of abattoirs processing cull sows - pigs that have reached the end of their reproductive lives - and is responsible for the slaughter of some 60 per cent of such sows in the UK.

"The distance that livestock have to be moved has been a concern, particularly of the farming community, for some time - the pressure on the abattoirs is for bigger, better and more efficient abattoirs. There's a price advantage there."

Government ministers stress that specialist abattoirs such as the Cheale Meats slaughterhouse have been in existence for years and that better culling regulations and monitoring have enabled the speedy identification of foot-and-mouth this time.