EUFMD |
Foot-and-Mouth Disease |
Foot-and-mouth disease (FMD) is a highly contagious viral disease of cloven-hoofed animals. The disease is characterised by the formation of vesicles (fluid-filled blisters) and erosions in the mouth, nose, teats and feet. Although not very lethal in adult animals, it causes serious production losses and is a major constraint in international trade.
OIE List A disease
Cloven-hoofed animals (ungulates) are susceptible to FMD. Of the domestic species, cattle, buffaloes, pigs, sheep, goats and deer are susceptible. Horses are not affected.
The FMD situation has improved markedly in recent years particularly in Europe and some countries in south east Asia and South America. However, the disease remains endemic and at a high prevalence in many countries in Africa, the Middle East, Asia and South America.
Europe, North and Central America, Pacific nations and the Caribbean are free of the disease.
FMD should be suspected wherever vesicles are seen in cloven-hoofed animals. Vesicles begin as mall white fluid filled areas that quickly grow to a blister about 3 cm in diameter. Two or more blisters may join to form a large one. The blisters usually burst leaving a raw surface. These heal over a few days. Other suggestive signs include:
the earliest signs are dullness, poor appetite, fever. Salivation and lameness may be seen. Vesicles appear inside the mouth on the tongue, cheeks and gums, lips and palate. Vesicle may form between the claws of the feet and along the coronary band. There may also appear on the teats and udder — reduced lactation, mastitis and abortion are common. Mortality in adults is usually very low. However, up to 50% of calves can dies due to cardiac involvement, secondary infections, exposure and malnutrition.
the main sign is lameness. There is also fever and loss of appetite. Vesicles form along the top of the foot, on the heels and between the claws. The feet are sore and affected pigs prefer not to move. Vesicles may also be form on the snout, but tend to rupture quickly. Abortion is common. Mortality in piglets can be high
the disease is usually milder with fewer lesions. Affected sheep are depressed and reluctant to stand. Some animals may get a sudden lameness. Vesicles form around the top of the foot and between the claws. Lesions may develop on the tongue and dental pad, but can be hard to detect. Significant mortality can occur in lambs.
In addition to the lesions described above, vesicles may also be present in the rumen. In young animals there is focal necrosis of cardiac muscle.
From live animals collect vesicular fluid, vesicular fluid epithelium, oesophageal-pharyngeal fluid and whole blood. From dead animals tissue specimens should be taken — lymph nodes, thyroid, adrenal, kidney, spleen and heart.
Unpreserved samples should be forwarded chilled, but should be frozen if delays greater than 48 hours are anticipated.
Blood collected in plain tubes and the sera separated.
Samples of lesion tissue, rumen pillae
Unpreserved tissue and blood specimens should be forwarded to the laboratory chilled with ice or frozen gel packs (dry ice if delays of more than 48 hours are expected) in specially approved containers.
FMD is one of the most contagious diseases of animals. Animals can become infected through inhalation, ingestion and through reproduction. The primary mechanism of spread within herds is by direct contact, through inhalation of virus aerosols. Under the right conditions long distance spread (measured in kilometres) of FMD by wind-borne virus can occur. This general requires a potent sources of aerosol virus e.g. an infected piggery, high humidity, stable atmospheric conditions and exposed livestock downwind.
Movement of infected animals is the most important method of spread between herds. Other sources of infection include contaminated vehicles, equipment, people and products.
FMD virus can survive for long periods in meat if pH does not fall below 6.2. It can also survive in frozen lymph nodes, bone marrow and viscera. FMD virus will also survive well in salted and cured meats, and in non-pasteurised dairy products.
It has been shown experimentally that FMD can be transmitted through artificial insemination where the donor was infected.
The highest risk of entry of FMD is through imports of susceptible live animals, contaminated meat or dairy products from infected countries. Virus can survive for long periods in a range of fresh, partially cooked, cured and smoked meats, and in inadequately pasteurised dairy products. These could be brought in with passengers on aircraft and ships, through the mail or on fishing vessels or yachts.
To eradicate the disease a “stamping out” policy can be applied. This involves quarantine, movement restrictions and slaughter and disposal of all affected an in-contact livestock on affected premises followed by cleaning and disinfection.
Inactivated vaccines have been successfully used in many parts of the world. Although protected against disease, vaccinated animals are not totally resistant and can still become infected and shed virus. Resistance falls fairly quickly, so animals must be revaccinated at regular intervals (4-6 months) to maintain immunity.
© European Commission for the Control of Foot-and-Mouth Disease
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