Foot And Mouth Disease

May 2010

An outbreak of a foreign animal disease, such as Foot and Mouth Disease in the Saskatchewan livestock industry would result in severe economic losses. Effective eradication will require resources and co-operation by all levels of government.

Saskatchewan Agriculture is currently working with Emergency Preparedness Canada, Emergency Planning Saskatchewan and the Canadian Food Inspection Agency (CFIA) to ensure Saskatchewan is ready if there is a foreign animal disease outbreak.

Working in co-operation, these agencies are reviewing the Foreign Animal Disease Eradication Support (FADES) plan for Saskatchewan. FADES provides CFIA with the support it requires from federal, provincial and local agencies to ensure a co-ordinated and efficient eradication of a foreign animal disease outbreak. Saskatchewan Agriculture is also receiving updates on the control measures in place to protect Canada from a foreign animal disease outbreak.

CFIA is the lead agency for Foot and Mouth Disease.

Foot and Mouth Disease is not a public health risk
Only a few human cases have been reported in spite of people's regular exposure to infected livestock. The cases that have occurred were due to close contact with infected animals, a virus in the laboratory or consumption of unpasteurized milk. In humans, the disease is mild and lasts for approximately one week.

If Foot and Mouth Disease occurred in Canada, it would cause severe economic loss due to trade restrictions
Foot and Mouth Disease is the world's most important animal disease, even though the mortality rate is low. The disease causes significant economic losses for the livestock industry. The most important economic effects result from loss of production, the expense of eradication, and the interference with the movement of livestock and livestock products between countries.

Where is Foot and Mouth Disease found?

The disease is currently present in many areas of the world. Canada, the U.S., North and Central America, Australia, New Zealand, Chile, and several other countries are considered free of Foot and Mouth Disease.

In North America, Foot and Mouth Disease was last reported in 1929 in the U.S., 1952 in Canada and 1954 in Mexico.

Clinical Signs
Foot and Mouth Disease is an extremely serious livestock disease and it is one of the most contagious animal diseases. This severe, viral disease affects cattle, pigs, sheep, goats, deer, elk and other cloven- hoofed animals. Some rodents, hedgehogs and elephants are also susceptible, but do not develop clinical signs. Most species show similar symptoms. However, those who show little or no clinical signs can still spread the disease.

Following an incubation period lasting between two and eight days (maybe up to 21 days), clinical signs become evident. The disease is characterized by salivation, depression, anorexia and lameness caused by the presence of painful vesicles in the epithelium of the tongue, gums, lips, nostrils, coronary bands, interdigital space and teats. The vesicles rupture, leaving large denuded areas, which may become secondarily infected. Many animals recover, but the disease leaves them dehabilitated. Clinical signs and lesions in pigs, sheep and goats are milder than in cattle. Lameness is the predominant sign in sheep, goats and pigs.

Transmission
The virus is present in tissues, excretions and secretions, including milk, blood, semen, urine and feces before the onset of clinical signs. Foot and Mouth Disease spreads by direct contact between infected and susceptible animals, and by indirect contact with contaminated animal products (meat, raw milk, hides) feed, bedding and equipment. Airborne spread of the Foot and Mouth Disease virus occurs where large numbers of animals, especially pigs, are infected, and there is an appropriate relative humidity greater than 60 per cent.

The virus spread is within 10 km of its source. With the right wind conditions the virus could spread as far as 250 km.

Pigs are the most potent excretors of airborne virus and cattle the most susceptible to airborne infection. Up to 50 per cent of cattle, sheep and goats can become carriers for up to two years in cattle, and one year in sheep and goats, while pigs can carry the virus for up to one month. Carriers may present a potential for virus maintenance. Wild fauna may serve as a reservoir for this disease.

Foot and Mouth Disease is a stable virus outside the host
Foot and Mouth Disease virus has strong environmental stability and has been found to be viable in contaminated milk after pasteurization at 72 ^oC for 15 seconds. It can also survive freezing temperatures.

The virus can survive outside the host for extended periods of time. Some reports indicate the Foot and Mouth Disease virus has been recovered from cattle stalls 14 days after removal of infected cattle, from urine after 39 days, from soil after 28 days in autumn, after three days in summer, and from dry hay at 22 ^oC after 20 weeks of storage. Other reports indicate the virus can survive one month in frozen bull semen, 50 days in water, 35 days on cardboard, wood or metal contaminated with serum or blood.

The virus can survive in the bone marrow, viscera, blood vessels and lymph nodes where acid production is reduced. The development of rigor mortis inactivates the virus, but quick freezing suspends acid formation and the virus is likely to survive.

Destroying the virus

The virus is inactivated by sunlight, extremes in pH and high temperatures.

It can be destroyed by:

• Heat (56 ^oC for 30 minutes)
• By drying;
• By acid below the pH level of 5 or lower; or
• By alkaline levels of pH over 11.

Vinegar diluted one to one with water is effective at killing the virus. Sodium hydroxide or formalin, one to two per cent, or sodium carbonate, four per cent, will destroy the virus within a few minutes.

Controlling the spread of Foot and Mouth Disease

Risk of Human Transmission of the disease

There are many factors to consider when determining the risk for mechanical transmission of Foot and Mouth Disease by human travelers:

• Contact with an infected animal (depends on the travelers activities);
• Ability to act as a biological or mechanical vector; and
• Contact with and transmission to a susceptible host or vector.

It is possible that human travelers can transmit Foot and Mouth Disease to animals. A study done by the U.S. Department of Agriculture in 1998 concluded that Foot and Mouth Disease is at moderate risk for mechanical transmission from humans to animals.

An outbreak can occur when:

• People wearing contaminated clothes, footwear, or equipment pass the virus on to susceptible animals. The virus may survive in the nasal passages of people from 28 to 36 hours.
• Animals carrying the virus are introduced into susceptible herds. Infected animals shed the virus in breath, saliva, manure, urine, milk and semen.
• Contaminated facilities and vehicles are used to hold and move susceptible animals.
• Meat and animal products infected with the virus, or raw or improperly cooked food waste containing infected meat or animal products is fed to susceptible animals.
• Infected semen, embryos, biologics and hides.

If Foot and Mouth Disease is identified in Canada, exports of animal and livestock products would stop.

If Canada had a confirmed case of Foot and Mouth disease, our borders would be closed for export of:

• Live ruminants and swine;
• Fresh or frozen meat of ruminant or swine origin;
• Semen;
• Embryos;
• Hides;
• Raw wool; and
• All other products derived from ruminants and swine.

Other commodities such as horses, commercial poultry, dogs and cats may also be prohibited because of the chance they might indirectly carry the virus.

The borders may be closed until Canada contains the disease, which may be longer than six months. If vaccination is used the waiting period is extended to one year.

Why not vaccinate?
Vaccination is not the first choice.

Vaccination would jeopardize Canada's Foot and Mouth Disease-free status.

Vaccination for Foot and Mouth Disease is not the first choice for controlling Foot and Mouth Disease. Canada would lose its Foot and Mouth Disease-free status if animals were vaccinated for the disease. It is difficult to distinguish healthy vaccinated animals from diseased livestock.

Foot and Mouth Disease virus is a member of the picornaviridae family of viruses and there are seven immunologically and serologically distinct types of Foot and Mouth Disease (A,O,C, Southern African Territories (SAF1,SAT2,SAT3) and ASIA 1) with as many as 60 subtypes. Infection with one type fails to provide immunity to infection with other types. Some serotypes do not cause any clinical signs in some species and yet spread the virus to susceptible populations

Enhanced biosecurity
Enhanced biosecurity on every producer's farm is also key to controlling this disease.

Canadian producers should:

• Avoid travelling to countries experiencing an acute outbreak of Foot and Mouth Disease until it is contained.
• If you must travel to areas experiencing an outbreak of Foot and Mouth Disease, do not visit farms or areas with livestock, including cattle, sheep, pigs, goats, deer, antelope, llamas, alpacas, elephants and hedgehogs. Remain in urban surroundings and avoid country walks or hikes, farm bed and breakfasts or other rural activities.
• Do not bring back any meat, dairy or other animal products.
• Disinfect all clothes (dry clean, or launder all clothes with bleach or washing soda and disinfect luggage), footwear (remove soil, take a bottle of vinegar to disinfect your shoes), and equipment (e.g. camera) and take a thorough shower before arriving home. Take a disposable camera and have pictures developed before you leave.
• Answer all the questions on the Canada Customs form accurately and follow all the directions at the airport upon arrival in Canada.
• Stay away from Canadian farms for at least 14 days.
• Be aware of the latest information on which countries have Foot and Mouth Disease.
• Do not host any farm tours or allow visits to anyone who has recently visited or resides in a country with a current Foot and Mouth Disease outbreak. A special precaution should also apply to all countries that are endemic for Foot and Mouth Disease.
• Know who is visiting your farm and where they have been. Do not let anyone on your farm if they have arrived less than 14 days from a country with Foot and Mouth Disease.
• If visits are necessary, provide visitors with boots and coveralls to be worn during their visits. Insist that all visitors disinfect their footwear with vinegar or Virkon solution.

Reporting potential cases of Foot and Mouth Disease

The field veterinarian must be able to recognize suspicious cases and notify the CFIA immediately. Foot and Mouth Disease is clinically indistinguishable from vesicular stomatitis and other viral mucosal diseases and therefore laboratory facilities must be available to confirm the diagnosis. In Canada, Foot and Mouth Disease is a federally reportable disease under the Health of Animals Act.

If this disease is suspected on a farm, contact the CFIA district veterinarian immediately.

CFIA will take the lead role in controlling this disease if it should come to Canada. If the disease is suspected, the farm will be quarantined until confirmatory tests are completed. Foot and Mouth Disease is classified as a List A disease by the Office International Des Epizooties (OIE) and has serious implications for trade.

CFIA website http://www.inspection.gc.ca/english/toce.shtml  or call toll-free 1-800-442-2342

For more information, contact Dr. Greg Douglas, Chief Veterinary Officer, Saskatchewan Ministry of Agriculture at 306-787-5547.