Foot and Mouth Disease (
FMD) is an
acute and highly contagious
picornavirus infection of
cloven hooved animals. The
virus (FMDV) is sensitive to
environmental influences, such as
pH less than 5,
sunlight and
dessication, however it can
survive for long period of time at
freezing temperatures.
FMD is present in many countries of the world, but not in North and Central America (north of Panama), Australia, New Zealand, Great Britain and Scandinavia. The European Union (EU) countries are generally free of FMD. FMD was last reported in 1929 in the U.S.A., 1952 in Canada, and 1954 in Mexico.
The disease is highly contagious and may spread over great distances with movement of infected or contaminated animals, products, objects, and people. Pigs are mainly infected by ingesting infected food. Waste feeding has been associated with outbreaks. Cattle are mainly infected by inhalation, often from pigs, which excrete large amounts of virus by respiratory aerosols and are considered highly important in disease spread. Large amounts of virus are excreted by infected animals before clinical signs are evident, and winds often spread the virus over long distances.
People can be infected through skin wounds or the oral mucosa by handling diseased stock, the virus in the laboratory, or by drinking infected milk, but not by eating meat from infected animals. The human infection is temporary and mild. FMD is not considered a public health problem.
The incubation period is from 2 to 21 days (average 3-8) although virus is shed before clinical signs develop. The rate of infection (morbity) can reach 100%, however mortality can range from 5% (adults) to 75% (suckling pigs and sheep). Recovered cattle may be carriers for 18 to 24 months; sheep for 1 to 2 months. Pigs are not carriers.
Clinical signs in cattle are salivation, depression, anorexia and lameness, caused by the presence of painful blisters in the skin of the lips, tongue, gums, nostrils and teats. Fever and decreased milk production usually precede the appearance of blisters. The blisers rupture, leaving large areas which may become secondarily infected. In pigs, sheep and goats the clinical signs are similar but milder. Lameness is the predominant sign.
Because of the range of species affected, the high rate of infectivity, and the fact that virus is shed before clinical signs occur, FMD is one of the most feared reportable disease in North America. An outbreak of FMD would, (and has in the past) cost millions in lost production, loss of export markets, and loss of animals during eradication of the disease. The significance of many other reportable diseases is due to their resemblence to FMD and the importance of distinguishing between them at the earliest indications of an unusual disease outbreak.
At the time of writing, there is an outbreak in the UK. The rugby union match between Ireland and Wales in Cardiff has been cancelled due to fears that travelling supporters could carry back the infection. New emergency powers have given councils the authority to close public footpaths and rights of way as a temporary precaution; It could mean huge areas of the UK countryside will be out of bounds to the public.
Travellers from the United Kingdom to Germany are being searched for shrink-wrapped meat before being allowed to enter the country.
Foot and Mouth is a Very Bad Thing(tm).