Foot and mouth disease poses serious economic threat, even in United States
03/21/2001

HAYS, KS -- Not much has been reported in the mainstream media on the dangers posed to the U.S. livestock industry by foot and mouth disease, but the threat is potentially devastating.

Dr. Garry Brower, an associate professor in the Department of Agriculture at Fort Hays State University, tells a story that illustrates the danger of complacency toward a disease that could cripple America's $36 billion-a-year beef industry, the $27 billion-a-year pork industry and the $2.5 billion-a-year sheep and lamb industry, if foot and mouth gains any toehold at all in the U.S. livestock population.

Several years ago, a case of infectious stomatitis in horses was confirmed at a major stock show and rodeo, said Brower, but before the mandatory quarantine could be enforced many of the participants made concerted efforts to escape the quarantine.

"They were taking any route out of the area, back roads, ranch roads, anything to get out of there. The horse owners, for the wrong reasons, were heading out," he said. "As far as controlling diseases, it was the worst thing in the world that could have happened. If their horses had it, they could have been the 'West Coast distributors' for the disease. Well, it ended up they had it isolated on one horse, but that's one of the diseases, it could have been something like this," he said, referring to the way foot and mouth disease has spread rapidly throughout Great Britain and into Ireland, France and now the Netherlands.

Foot and mouth disease is a very serious disease indeed, even though it is rarely fatal to adult animals. The virus causes painful inflammation between membranes and in the heart and lungs and underneath the skin. Vesicles, or blisters, develop in the mouth and on the feet and provide sources of virus that are expelled into the air and soil. Standing hurts, eating hurts. Young animals die as a result of myocardial (heart) complications, generally before the sores appear in the mouth and on the feet.

The effects are extreme, resulting in weight loss, spontaneous abortion and difficulty in conception. Recovery takes months and, in the case of dairy cattle, milk production rarely returns to pre-infection levels.

The mortality rate is less than 10 percent, mostly in young animals, but there is no cure and, with seven major serotypes and 61 strains among the types, there is no effective vaccine.

Animals inoculated with live virus are, in fact, carriers and can transmit the disease to any other cloven-hoofed animal -- cows, sheep, pigs -- for up to 30 months.

The vaccine is effective for only four to six months, and only for the particular serotype and strain of virus used in the vaccine. The vaccinated animal is still vulnerable to the other strains of FMD.

And the disease is fearsomely contagious.

Brower noted that a documented case shows that the "plume" exhaled by a diseased cow can carry infectious levels of aerosolized FMD virus for 30 miles when humidity is 60 percent or more and the wind is non-turbulent. The virus will live in the soil for up to 28 days in winter and three days in summer. It will survive in urine for 39 days, dry feces for 14 days in summer, and in slurry -- manure in holding ponds -- for six months in winter.

Infected cattle will shed infectious amounts of the virus into feed and bedding. All excretions and secretions, including milk and semen, will contain the virus. The incubation period is from two to 14 days.

Transmission to humans is rare but can occur and results in a disease called aphthous fever. The symptoms are fever, vomiting, hot flashes, dry mouth and sores on the lips, tongue and cheeks. It lasts for from seven to 10 days and, as in ruminants, can involve the heart and lungs.

The United States has been free of FMD since 1929, when the last of nine outbreaks was eradicated, but that is only because the disease has been kept out through strict regulation and watchfulness and the rigorous applications of a "negative" control program. That means that if the disease is confirmed, the animal is destroyed and burned. Treatment is economically unfeasible.

The strictly enforced negative control program used by the United States has kept FMD out for more than 70 years, but it has to be maintained just as strictly. If FMD did arrive in the United States -- with its population of more than 98 million uninfected but vulnerable cattle, more than 60 million pigs and more than 9 million sheep -- there is a high probability that the disease would, in Brower's words, "spread like wildfire."

"The mortality is less than 10 percent because it really doesn't kill them," said Brower, "but sometimes you wish it would because their production and growth drops dramatically, you're pumping money into them with antibiotics for secondary infections and supportive care, plus the fact that the cost of this thing is unending. The way this disease is, it's just like water running down a hill. The costs just keep coming in."

One of those costs is disinfecting. A primary means of transmission is through what are called "fomites," which are inanimate objects that pick up the virus from infected animals --clothing, shoes, shovels, gloves, farm equipment, trucks, trailers, sheds or anything else in proximity to the animals.

So in addition to the cost of the lost production, there is the cost of disinfection. The pens
have to be cleaned, the dirt stripped down a number of inches and the soil limed to kill any virus that may be there. Then a high-pressure wash is applied to all of the feeders, waterers, fences, buildings, everything around, and then the same things must be sprayed with acetic acid. These steps are necessary before animals can be brought back into the pens.

"The costs would be unbelievable," said Brower.

The outbreak in England began with an infection on one farm in Essex County in mid-February. Foot and mouth disease has now spread across the United Kingdom and jumped the English Channel to mainland Europe. By March 20, in England alone, more than 379 cases had been confirmed. The American Veterinary Medical Association, which is tracking outbreaks around the world on its Web site, reported that as of March 19, the United Kingdom had slaughtered 223,564 animals. Of these, 159,874 carcasses had so far been destroyed and another 95,872 animals were awaiting slaughter.

In the United States, economic losses from a large-scale infection could be devastating. The figures cited above are only for direct sales of cattle, calves, sheep and hogs. Cattle-Fax, which provided the $36.5 billion figure for cattle, for instance, also estimated that secondary economic activity related to beef at five times that amount. U.S. cattle, which make up only 10 percent of the world's cattle inventory, produce 25 percent of world beef supply.

Brower points to the rapidity of the spread of foot and mouth disease in Great Britain as a compelling argument against complacency. The infection in England has already been documented in more counties than were affected by the last outbreak in 1969. During that episode, more than 440,000 animals were destroyed.

He believes that, if the disease does appear in the United States, it will probably arrive through illegal entry of either people or material.

"You have to look at the legal entry, but the drug trade could bring it in, too," he said. "In my feeling, because of the way they're going on this aggressively, it's not going to be animal products bringing it in. It's probably going to be travelers bringing it in -- probably coming in on a human, fomite basis."

The United States has prohibited imports of most products made from ruminant or swine, untanned hides and skins, raw, unwashed wool, hair or bristles, glue stock, bones, horns, hooves and products made from blood or other animal byproducts.

Travelers may have to disinfect shoes and luggage and may be asked if they've been to farms abroad and, if so, if they are planning to travel to farms and ranches in the United States.

If the disease does arrive, it must be taken extremely seriously from the first moment. It will spread not only through domestic livestock, but will infect wild animals such as deer and buffalo, and then they become carriers, or vectors, for reinfecting domestic livestock.

"We have the rules and regulations to control serious diseases but we need equally strong enforcement," said Brower.

"We have the capability of transporting animals to the coasts within 72 hours and, in some cases, we have areas that don't give a whistle about the health regulations."

The same miracles of modern travel that are available to cattle, sheep and pigs is also available to whatever is traveling with or in them.

"We've got to take it seriously," said Brower.


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