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Foot-and-Mouth Disease: Will it spread to the U.S.?

by 5m Editor
8 March 2001, at 12:00am

Animal health officials in Texas are watching with concern the relentless westward march of foot-and-mouth disease (FMD), the most recent outbreak of which was confirmed in late February at several sites in England, where livestock operations already have been financially ravaged by the brain-wasting disease, BSE (bovine spongiform encephalopathy) and outbreaks of the viral infection, hog cholera.

Additional cases of FMD have been detected among cattle, sheep and swine in Great Britain (encompassing England, Wales and Scotland). In addition to the loss of thousands of animals, British farmers may lose as much as $73 million just from the week-long ban (which could be extended) on the transport and marketing of livestock susceptible to the disease.

Foot-and-mouth world-wide

Not in US since 1929

FMD, which has not been seen in the U.S. since 1929, is caused by a highly infectious virus that can cause death or disabling blisters and sores in and around the mouth, muzzle, teats and feet of livestock with cloven or split hooves. Cattle, pigs, sheep, goats and deer are highly susceptible, and can exhibit clinical disease signs after an incubation period of only three to eight days. To stop the spread of infection, affected or exposed animals must be slaughtered, then burned or buried. Premises and equipment must be disinfected to prevent disease spread.

Special Challanges

Foot and mouth virus poses special challenges, requiring proper disinfection and biosecurity protocols. People who have worked around or been near infected animals can inadvertently carry and spread the virus via their equipment, cars, clothing, shoes, or even for a short time in their lungs or pharynx (throat), said Linda Logan, Texas' state veterinarian and head of the Texas Animal Health Commission (TAHC), the states livestock health regulatory agency. She pointed out that studies indicate the virus can drift up to 40 miles on the wind, another hurdle to confining an FMD outbreak to a defined geographic area.

Economically Damaging

FMD is probably the most economically damaging livestock disease, said Dr. Logan. The disease is currently affecting four of the worlds seven continents: Asia, Africa, South America and Europe, leaving only North America, Australia and Antarctica free of the disease.

An outbreak costs a country millions of dollars to fight, and thousands of animals can be lost. Additionally, livestock markets must be closed to prevent spread of infection, dairies may not be able to operate, and transportation of livestock must cease. Furthermore, theres the cost of depopulating and disposing of affected or exposed animals and vaccinating clean animals to create a disease-free buffer zone, said Dr. Logan, a specialist in tick-borne and foreign animal diseases. She also serves on a national team reviewing how best to safeguard U.S. livestock from foreign diseases and pests.

Dr. Logan urged livestock producers in Texas to step up their surveillance and to take precautions to protect herds from possible contamination. If youve traveled internationally, dont risk carrying disease home to your herd. Disinfect your boots before working with your livestock. Producers who feed wastefood to swine should be particularly careful to ensure that all scraps are well cooked, she said. She also suggested that producers limit vehicle traffic and visitors onto their premise, and keep new animals isolated for several days prior to adding them to the existing herd.

If in Doubt Call!

If your livestock become lame or develop blisters or sores, call us at 1-800-550-8242. Our emergency response within the first 24 hours after the first signs of disease will affect our outcome over the next six months, Dr. Logan said. The TAHC and U.S. Dept. of Agricultures Veterinary Services in Texas operate the toll-free number 24 hours a day for emergency calls.

Vaccination only Emergency option

While FMD vaccine is available, Dr. Logan said it is used only in emergencies, to create a disease-free buffer zone around an infected area. Because vaccinated animals will test positive, they cannot be shipped internationally and protocols require the animals to be destroyed as soon as the disease is eradicated.

Most importantly, FMD outbreaks result in trade embargoes imposed by other countries, said Dr. Logan.

South Korea, for instance, had been free of FMD since l934, but was struck by the virus in late March 2000, she reported. Producers in that country intended to export $400 million worth of pork in 2000, but Japan and its other trading partners immediately shut their doors to South Korean exported animals and products. It can take years to be declared disease-free and reestablish international marketing opportunities.

Consider the damage to our economy, if we were to have the disease introduced into the U.S. and exports of live animals and meat were prohibited. Last year, the U.S. shipped out more than $4.2 billion worth of these commodities. Texas ranked third among all states, shipping out more than $736 million in animals and meat products, she said.

For years, we worried about domestic regulatory diseases that are tame compared to the devastation of foreign animal diseases, said Dr. Logan. A global economy brings with it global risks, and we must be prepared for the inevitable threats posed by international trade and travel.

Air Travel

I am particularly concerned when cases of FMD occur close to a highly populated area--or near a major international airport, said Dr. Max Coats, who heads up the TAHCs animal health programs and field operations. Because of the virus ability to ride the wind, its possible that ranching or farming equipment being exported from affected countries could be contaminated. It may sound far-fetched, but with a disease of this impact, were always concerned about potential scenarios. Within 24 hours, an animal, animal product, person or piece of equipment can be transported nearly anywhere in the world. Theres always a chance that a virus, pest or dangerous bacteria will be hitching the ride, too.

Then there are the items travelers like to tote on long flights, such as sandwiches, delicacies or other food items that could be contaminated by the virus, he said. Although direct flights from countries affected by FMD are checked carefully, Dr. Coats said theres always a risk that contaminated items could be smuggled or inadvertently brought into the country by the millions of visitors and returning U.S. citizens who travel internationally. Around 4.5 million British residents, for example, came to the U.S. on direct flights in l999.

Outbreaks in two dozen countries in last 2 years (see map)

During the past year, more than two dozen countries have been plagued by outbreaks of FMD, and the virus continues to migrate westward, noted Dr. Logan. In early March 2000, Japan reported its first cases since l908, and Japanese authorities laid blame on imported straw contaminated with the virus.

Within two weeks of the initial case, Japanese livestock authorities checked more than 25,000 dairies, nearly 27,000 beef cattle farms and almost 3,700 pig farms to determine if there was additional infection, said Dr. Logan. If this scenario occurred in Texas, the TAHC field staff would be unable to handle this enormous task alone, and we would have to summon help from private veterinary practitioners, our partners within the states emergency management system, and our federal counterparts in the USDA. (Of the 215 TAHCers about 100 are livestock inspectors and around 20 are veterinarians.)

Swine are highly efficient and effective hosts for FMD, said Dr. Coats. And, with more than two million wild or feral swine in Texas, our challenge would be nearly insurmountable if the disease became established in this free-ranging population.

By Valentines Day 2000, reports indicated that more than 500 animals had died from the disease in eastern Mongolia, a large country bordered on the south and east by China (also affected) and by Russia to the north. A year later, FMD outbreaks continue in Mongolia, where winter blizzards also wiped out more than 1.5 million animals.

By Easter last year, Russia reported cases among swine herds in its eastern regions, and in late spring, infection was detected at a pig farm in Kazakhstan, which shares borders with China and Russia. In August, infection drifted southward into the small country of Tajikstan where cases among cattle and sheep herds were reported.

Two free-grazing cattle herds in northeastern Greece, near the Turkish border, were struck by the disease in July 2000, and surrounding cattle, goat and swine herds were destroyed. In the fall, Turkish governmental authorities requested more than $43 million in international aid to curtail livestock smuggling in its eastern and southeastern regions and stop the introduction of FMD and its potential spread into Europe.

South American countries were hit by infection in late summer 2000, said Dr. Coats. Paraguay was struck first in early August, followed by outbreaks in Uruguay and Colombia. Argentinean officials blamed their countrys outbreak on cattle smuggled from Paraguay. An Argentinean newspaper reported that as many as 20,000 head were illegally smuggled in from Paraguay.

When a Brazilian dairy was hit by the disease, Brazil's minister of agriculture reported that he suspected bioterrorism, as the virus was of a different strain than the one detected in Paraguay and Argentina. (FMD virus has as many as seven types and 70 differing strains.)

Argentina is the worlds fourth-largest cattle-production country, and producers had planned to expand their exports by $5 billion in 2000. Brazil is the worlds largest exporter of beef. Both countries lost their marketing opportunities when FMD hit the countries, said Dr. Coats.

When infection spread to Uruguay, the military shut down all human and animal movement and dropped food into the restricted area from helicopters, said Dr. Logan, who visited the country last fall. Animals in the affected area were euthanized and buried within 24 hours, which stopped the spread of disease. Uruguayan officials and producers had prepared for such an outbreak ahead of time by setting up funds to pay producers for their livestock losses.

FMD also wreaked havoc in South Africa in summer 2000, when viral-contaminated wastefood was off-loaded from a foreign vessel and fed to swine.

Simulated outbreak in Texas

This situation mirrored the scenario for the tabletop emergency disease exercise in November, conducted cooperatively by the U.S., Canada and Mexico, said Dr. Coats. In the simulated outbreak, a South Texas producer collected contaminated wastefood from a foreign ship and fed it to his pigs. Within two weeks, routine livestock marketing and movement could have spread the disease across Texas and into several states and Canada. We estimated it would have cost $50 million to eradicate the disease just in Hidalgo County.

We're monitoring the movement of FMD closely. Buffer zones and existing prevention efforts seem to have failed, as one after another, countries are hit by the disease, said Dr. Coats. Foreign animal diseases, like FMD, are the gift that keeps on giving, as demonstrated by the 2001 resurgence of infection in Taiwan, after the country lost nearly all of its swine herds in l997 outbreaks.

Outbreak in UK

This most recent FMD outbreak affecting England was initially detected by a veterinarian inspecting pigs at a slaughter plant in a town northeast of London. Since then, cases have been disclosed throughout Great Britain, which has about 157,000 livestock farms, commented Dr. Coats. He said British authorities believe the virus may have been introduced through the feeding of contaminated wastefood to swine. Sheep on a nearby farm were exposed and may have spread infection to as many as 25,000 animals when they were hauled to three markets.

Livestock shows in Great Britain have been cancelled, and animal parks and zoos have been closed. Horse events also have been postponed, even though equine are not susceptible to the disease. Fears are that the virus could be carried and spread either by the horses hooves or by the vehicles used to transport the animals, commented Dr. Coats. He said French authorities are destroying more than 47,000 British sheep that were recently imported. He pointed out that, in Germany, authorities are taking precautions, destroying susceptible animals that were recently shipped in from Great Britain. In the Netherlands, more than 4,300 susceptible livestock and deer have been killed on farms that have links to Great Britain. Livestock markets in the Netherlands also are being closed for a week, he said.

Feeding contaminated meat

Worldwide, nearly two-thirds of the FMD outbreaks are attributed to the introduction and feeding of contaminated meat, meat products or garbage to animals, said Dr. Logan. She said about a quarter of infection is spread by airborne transmission, and about 10 percent is comprised of infected livestock importations or contaminated objects and people.

The FMD situation is a lot like watching a hurricane develop. We cant pinpoint its next landfall, but we know its direction. We must be prepared to take action immediately if the virus is introduced into the U.S.--or Texas, said Dr. Logan.

For further information contact:

Texas Animal Health Commission
Box l2966 Austin, Texas 78711
TEL (800) 550-8242
FAX (512) 719-0719
Contact: Carla Everett, information officer.
TEL: 1-800-550-8242, ext. 710,
EMail: [email protected]