The Ecologist Provides Overview of “Slash and Burn” Control in the UK
By Diane Schivera
Foot and Mouth Disease (FMD) has other common names: hoof and mouth disease, aftosa (other diseases with similar symptoms use this name) and apthous fever. It is an acute, highly contagious disease caused by one of the smallest, filterable viruses known. Cloven footed animals such as cows, goats, pigs, sheep, deer, moose and English hedgehogs are susceptible to the virus. When infected the animals are lethargic, have an elevated temperature, begin slobbering and get blister-like, fluid filled vesicles around their mouths, muzzle, between and around their toes and on their teats and udders. The blisters eventually break open to form wounds, so the animals lose their appetites and become lame. Only rarely is the disease seen in humans and other carnivores. The symptoms would be the same but much milder. Most of the sources I read stated that FMD doesn’t affect humans at all. Young animals that are fed highly concentrated feed for rapid growth are particularly susceptible and usually die, and some young are aborted in utero. Those that survive gestation will have a low birth weight. Often dairy cattle are the most severely affected. They will have a drop in milk production and may develop chronic mastitis, lameness, or reproductive problems.
Seven types and 60 subtypes of the virus exist. Each type causes somewhat different symptoms, not only in severity but in relation to the areas of the body that are affected. The virus can spread on the wind or in saliva, exhaled air, milk, meat and dung of infected animals, and through contact with foodstuffs or other items contaminated by infected animals. Anyone who has attended diseased animals can spread the virus, as can dogs, cats, poultry, wild game, vermin, other wildlife and vehicle tires. Foot and mouth virus is very sensitive to heat and is removed through standard pasteurization. When kept in an incubator at 98 F., the virus loses infectivity within 48 hours. At room temperature it remains viable for two to three weeks. The virus is resistant to alcohol but sensitive to acids. It is also so sensitive to low ambient humidity that it is more likely to die in a desert or on sunny days than cloudy ones.
Animals begin shedding the virus a few days before they show clinical signs of the disease. Cattle, swine, sheep, goats and deer are highly susceptible and can exhibit signs of infection after an incubation period of only one to eight days, or the incubation period may last longer, and in sheep and goats it may go undetected altogether. The symptoms last for two to three weeks, and the animals take up to three or four months to fully recover. But, they will recover naturally. Foot and mouth disease is rarely fatal, often in less than 2 to 3% of the cases. It is a disease with a moderate to high morbidity but low mortality.
Many countries have a policy of eradicating all animals with FMD, as well as any animals close to infected animals. We have seen this in Great Britain and the countries of Europe that have had outbreaks recently. This policy is explained as being necessary because the disease causes so much economic loss. In many countries this is an endemic disease, present at low levels at most times. Occasionally outbreaks or epidemics occur, either from without or within the country. Countries that say they have FMD-free status always have the epidemic caused from without. These countries will only allow animals or fresh and cured meat products from other FMD-free countries to cross their borders. So if countries depend on export trade with these FMD-free countries, then the status becomes very important. This is where much economic loss occurs. The disease is endemic in most of Africa, the Middle and Far East, Mongolia, and some of South America. These countries either trade with each other or within their own boundaries.
The use of vaccinations to control FMD has been discouraged by all of the ‘free’ status countries. The USDA lists many of its reservations to vaccinations on its APHIS website (www.aphis.usda.gov). For example, an annual vaccination program would be required, and USDA believes that would be costly. It would also cause a false sense of security, because the vaccine will not protect against the disease but only against the symptoms. The animals can still harbor the virus in their respiratory tracts. Another risk is that the disease would be spread outside the vaccination zone by farmers or health care providers. If the United States vaccinated animals, it would have to wait three months after the slaughter of the last vaccinated animal to export to other ‘free’ status countries. But APHIS also says, “Vaccination can help to stop [the spread of the disease] quickly if used strategically to create barriers between infected zones.” In Argentina, “We do not use the ‘sanitary rifle,’” reports a farmer/organic certification inspector for the Foundation for Ecological Food of Argentina (FAEA) (personal communication with Beedy Parker); instead vaccinations are used in a ring around the focus of the disease. Vaccination is easier there because most of the animals are spread out on range land to graze, not packed closely into pastures or feedlots. Presently, Argentina will probably have to wait four years before it will have its ‘free’ status again, because infected animals were brought in illegally from Paraguay.
The use of vaccinations for FMD has other obstacles. The many types of the virus complicate its use. Also, FMD is a very quickly mutating disease, so more types of vaccinations need to be developed. A new test for the presence of the disease has been developed. The previous test was confusing because a positive result couldn’t differentiate between the presence of the disease and the vaccine, thus compromising the FMD-free status of a country. The new test can detect a marker genetically engineered into the vaccine. The recent situation in Great Britain might have been controlled with vaccination. The virus was known to be serotype O, for which a vaccine is available in large quantities. However, the British government was concerned about its trade status.
A great supply of literature is available on FMD right now. One of the most thought provoking pieces is from the Elm Farm Research Centre website (www.efrc.com/) in England. According to the writer, veterinarian Abigail Woods, a ‘killer plague’ hit England in 1865-67. That was the first time eradication, quarantine and export restriction methods were enforced by the government. It proved successful then, so a movement began to use it for other contagious ailments, including foot and mouth. At that time these other diseases were recognized as being less severe than the existing plague, but this view was rejected by a group of wealthy, influential breeders, whose stock were infected with a severe strain of the disease that had corresponding economic losses. These breeders effected legislation to enact draconian control measures, including import control for foot and mouth disease. In subsequent years farmers began to associate FMD not with a loss of milk and meat but with animal loss and trade barriers. So now the farmers will support these measures when enacted. In addition, the relatively recent emphasis on intensive livestock production methods has heightened the fear of FMD spreading rapidly through herds.
Foot and mouth is a very contagious disease that is more of a production problem than a problem of animals dying. Fatalities result primarily from the slaughter. When the disease occurred in Greece (granted, a dry climate) in 1994, it just faded out with the use of few control methods. Today diagnostic tests work within 40 minutes rather than the old 40 hours, and much time and investment has gone into developing vaccines worldwide. Should today’s high density stocking rates be reason to vaccinate, instead of the severe methods being used?
For information about reducing the risk of FMD on your farm, see the Maine Department of Agriculture website (www.state.me.us/agriculture/) or The American Livestock Breeds Conservancy website (www.albc-usa.org). Additional information can be found at: www.humanitarian.net/; and www.sheepdrove.com/.
The Ecologist Provides Overview of “Slash and Burn” Control in the UK
An article entitled “Burnt Out: What can the UK draw from the disease of foot and mouth” appears in the current issue of The Ecologist magazine (www.theecologist.org/). In it, Richard North, a former UK environmental health officer, provides a good overview of the “slash and burn” control efforts, and ably discusses the political dimensions as well. Here’s one excerpt:
“Britain, historically, had opted for disease-free status, an entirely realistic objective given its island status and its ability to maintain strong border controls. But, in 1993, with the advent of the EU’s ‘single market’ – which politicians of all three major parties heartily endorsed – the UK dismantled its border controls and opened up its markets to virtually unrestricted imports, legal and illegal. At a stroke, trade policy was ‘out of synch’ with the disease control needs. The only logical move then was to embark on routine vaccination, to protect against one of the most infectious diseases in the world. Amazingly, however, in 1990 MAFF had convinced the EU to adopt disease-free status, forcing continental member states to abandon vaccination. The scene was thus set for a disaster of epic proportions. But what really set the seal on the disaster to come was a paradigm shift in the way livestock was reared and marketed. Local markets and local abattoirs – driven by regulatory pressure – had given way to mass movement of animals, partly to serve a growing export market, partly to satisfy the needs of centralised supermarket buying and partly because of the critically reduced profit margins for sheep farmers. Hill farmers, unable to live off the income from traditional farming, increased stocking levels and became ‘nurseries’, keeping breeding ewes and shipping their progeny off the hills to be fattened on lowland grazing. This accounted for the massive movements of sheep which, ultimately, were to spread the disease.”
– Beedy Parker