A layman's guide to foot and mouth disease

Foot and mouth disease, also called hoof and mouth disease or Aftosa, is a highly contagious viral disease affecting particularly all cloven-footed mamals, including cattle, sheep, goats and swine. Wild herbivores, such as camels, bison, deer, antelope, reindeer, llama giraffe and elephants are also susceptible. Men in very rare cases may develop very mild forms of the disease. Horses, however, are resistant to the infection.

The disease is characterised by the formation of painful, fluid-filled blisters on the tongue, lips and other tissues of the mouth and parts of the body where the skin is thin, such as the udders and teats, between the two toes of the feet and the coronary band above the hoof. There are seven distinct types of foot and mouth virus and these types affect different species and produce symptoms of differing severity.

The virus is spread by both inhalation and ingestion. It forms a primary blister where it enters an animal's body. Within 24 to 48 hours it enters the bloodstream causing a fever. During this phase, lasting 24 to 36 hours, the virus is excreted in the saliva, the milk, the urine and the faeces.

A characteristic smacking of the lips ushers in the phase of the formation of blisters on the tongue, gums and lips. They rupture within 24 hours, leaving raw, inflamed and extremely painful surfaces that heal in one to two weeks. By this time the animal refuses to eat solid food. Blisters also appear on the foot, causing lameness.

The losses caused by foot and mouth disease are tremendous. The mortality in ordinary animal epidemics is only about five per cent but malignant forms of the disease have led to losses of up to 50 per cent.

In those animals that survive great losses in weight occur because the animals cannot eat. In surviving milk producing animals the flow of milk is sharply diminished. Abortions and mastitis are common and secondary infections are frequent. Surviving animals remain virus carriers for up to two years. Foot and mouth disease is endemic throughout the Middle East, much of Europe, Asia, Africa and South America.

The virus can survive for relatively long periods of time in the air, in food and garbage and even in the hides, hair and wool. Wind can spread the virus over long distances. The development of effective vaccines has helped control epidemics but has not eliminated the disease. There is no effective treatment for infected animals. The incubation period for the disease varies from two to 21 days but in most cases it is three to five days.

Foot and mouth can be destroyed by heat, low humidity, or certain disinfectants, but it may remain active for a varying time in a suitable medium such as the frozen or chilled carcase of an infected animal and on contaminated objects.

Doctors say there is no risk to human health. During the 1967 epidemic in Britain one human was diagnosed as having caught the disease and one child was suspected of having it. The disease should not be confused with the similarly named, but completely different condition called hand, foot and mouth disease, which can infect and cause illness, particularly in children.

This particular disease is caused by a Coxackievirus. This is not a different strain, it is a completely different, unrelated virus, which, incidentally, does not affect animals. Most childcare books will have a reference to this particular condition in the appendix at the back. Many parents will already have met this condition in their child.