Precautions Against Hoof and Mouth Disease

By Dr. Gavin Meerdink
Beef Extension Veterinarian

Considerable media attention has been given to the current outbreak of hoof and mouth disease (also known as foot and mouth disease) in the United Kingdom, where the disease had not been seen since 1967-68. Even though it has a low fatality rate, HMD is considered the world's most important animal disease. HMD is present in Africa, Asia, South America, and Europe. In 1997, more than 4 million pigs died or were slaughtered within two months during a devastating epidemic in Taipei, China. The last outbreak in the United States was in 1929; the disease was seen in Canada in 1951-54, and in Mexico in 1946-54.

HMD affects all cloven-footed animals. Horses are not susceptible to the disease. Humans are susceptible to a related enterovirus that causes hand, foot and mouth disease.

The virus that causes HMD is easily and rapidly transmitted through air, infected meat and milk products, clothing, or other means by which the agent can be carried to the next host. It is estimated that sufficient virus to initiate an infection can be windborne as far as 150 miles. Pigs are the most potent excretors of airborne virus, and cattle the most susceptible to airborne infections. Animals that have recovered from the disease can commonly continue to be carriers of the virus and remain infectious for as long as 6 months. The virus may persist for over one year on infected premises, for 12 weeks on clothing and feed, and for up to month on hair.
Guidelines for Prevention

According to Dr. Richard Hull, Illinois state veterinarian, the Illinois Department of Agriculture is requesting that, for 10 days after their arrival in the United States, persons who have been in designated endemic FMD countries not visit animal farms, sale barns, stockyards, animal laboratories, packing houses, zoos, exhibitions, and any other place where cattle, sheep, goats, deer and other ruminants, and swine may be present.

Under no circumstances should any meat or other animal products be brought into the United States - no matter how small or apparently safe. No clothing or footwear that was worn in the country experiencing HMD should be worn unless properly disinfected.

The virus can be killed using a 0.1 percent concentration of household bleach (1ounce bleach/gal. of water). If the area to be disinfected is heavily soiled, a 3 percent solution should be used (2.5 ounces bleach/gal. of water).
Signs of HMD

After an incubation period of one to seven days, animals quit eating, develop a fever of 104oF to 106oF, and develop vesicles--or fluid-filled blisters--on the oral mucosa and feet. The morbidity rate in outbreaks of HMD in susceptible animals can rapidly approach 100 percent, although the case fatality rate is generally less than 2 percent but slightly higher in younger animals. The severity varies widely between the different viral strains. More severe reactions can include heart failure, enteritis, and ascending posterior paralysis.

Vaccination is common in the countries where the disease occurs. Clinical disease is reduced by vaccination, but carrier animals still occur and can, in fact, be produced by the vaccine. These carrier animals are a potent method of spreading the disease and also provide an excellent medium for the mutation of existing viral strains.

Good Web resources about HMD can be found under "Current Topics" at dairynet.outreach.uiuc.edu and at aleffgroup.com/avisfmd/. Information about foot, hand, and mouth disease appears at www.iah.bbsrc.ac.uk/virus/Picornaviridae/.

###