Foot and Mouth Disease
Livestock Update, July 2001
Kevin D Pelzer DVM, MPVM, VA Maryland Regional College of Veterinary Medicine
The recent Foot and Mouth Disease (FMD) outbreak that began in the United Kingdom and spread to the European continent has stirred a lot of concern not only in Europe but throughout the world. Although there seems to be a hysteria about this disease, this disease has plagued mankind for centuries. Likewise, FMD is not that rare on a global scale. Taiwan had an outbreak in 2000 that resulted in extinction of the swine industry in a part of that country. Within the past year, outbreaks of FMD have occurred in South America, Africa, and Asia. The last outbreak in the U.S. was in1929. Although the disease does not kill animals, the costs associated with lost production, lost export markets and the costs associated with eradicating the disease are astounding. The cost of the outbreak in the UK has been estimated at $367,000,000 a week.
Foot and Mouth Disease is caused by a virus, Aphthovirus. There are 7 different virus serotypes and 61 different strains. The serotype involved in the UK outbreak is Type O. The virus is found in breath, saliva, feces, urine, milk and semen of infected animals as well as meat and by-products. The virus is highly infectious and can persist in the environment for up to 1 month, depending on the temperature and pH. Transmission of the virus may occur when susceptible animals come into direct contact with infected animals, people wearing contaminated clothing or foot wear, contaminated vehicles or livestock facilities, consumption of infected meat or animal products, contaminated drinking water or feed, or insemination with material from an infected sire.
Cloven footed animals; cattle, sheep, swine, and deer are susceptible. Elephants, hedgehogs, rats and humans may also be infected with and transmit the virus. Infection in humans is rare and clinical signs are mild flu like symptoms. Signs of infection in the cloven footed animals are blisters in the mouth and tongue, lips, nose, teats and in the interdigital space of the feet. Clinical signs consist of slobbering, shivering, fever, blisters and ulcers of the mouth, lameness, weight loss, abortion and reduced milk production. Clinical signs in sheep may be very subtle. Adult animals usually survive but there may be high mortality in young livestock. There is no cure for this disease and in most countries, infected animals are slaughtered in an effort to reduce transmission and eradicate the disease.
There is a vaccine for FMD but the vaccine has some limitations. Each vaccine contains a certain serotype and little or no protection occurs between the 7 serotypes. Therefore, the specific vaccine for the specific serotype involved is needed. Once animals are vaccinated, they develop a titre which can not be distinguished from a true infection. All animals once vaccinated would then be considered infected. As a result, countries utilizing vaccine, are considered infected and lose their exporting capabilities. When vaccine has been utilized, it is used in a manner to contain an outbreak. A diagnosis of FMD is made on a farm, animals on surrounding farms are vaccinated. The animals on the affected farm are slughtered. When all of the clinical cases of FMD have been eliminated, the vaccinated animals are slaughtered because they all test positive because of the vaccine. The vaccineated animals acts like a fire ring so that the virus can't jump beyond the vaccinated animals and spread to other farms.
If one suspects that they may have a case of foot and mouth disease, they should immediately call their veterinarian or state veterinary office, 804-786-2481. All animals on the property should be quarantined until a health professional examines the animals.
Prevention centers on biosecurity. New herd additions should be quarantined. Vehicles that are used to transport animals to market should be cleaned prior to reentry to the farm. Swine should not be fed raw garbage. Visitors to the farm should be asked if they have had any recent contact with livestock, and clean clothing worn and footwear disinfected prior to entry onto the farm. The USDA is recommending that persons visiting a country with FMD not visit farms 5 days prior to their departure from the foreign country, they should wash or dry clean their clothes prior to leaving, rewash or dry clean clothes upon arrival to the US, disinfect footwear and not visit or return to livestock areas for 5 days. Likewise, foreign animal products such as meat, dairy and raw fiber products should not be brought back from overseas visits.
Transmission occurs by:
Direct or indirect contact (droplets)
Animate vectors (humans, etc)
Inanimate vectors (vehicles, implements)
Airborne, especially temperate zones (up to 60 km overland and 300 km by sea - e.g. 1967 UK outbreak spread from France to Isle of Wight)
"Foot-and-mouth can be pretty transitory in sheep," he said.
"The lesions in the mouth clear up in a few days, and you may not notice the animals limping, because lameness is a common problem in sheep anyway.