Foot and mouth disease

Highly contagious virus that infects cloven hooved animals. It is a picornavirus and is also known by the acronym FMD.

Pigs can develop FMD if they eat infected food. The pig exhales respiratory aerosols which nearby cattle inhale. Cattle are worst affected by FMD. The symptoms include depression, lameness and, as the name suggests, the development of blisters around the mouth and between the digits.

The incubation period is 2 to 21 days. The virus can spread by hitching a ride on animals, objects, people or even the wind. Humans can catch the virus through contact with infected animals and drinking infected milk. However, in people the disease is usually very mild.

FMD can quickly devestate a herd. Sometimes entire herds have to be destroyed as a precaution. Constant monitoring of farms is needed. Europe, North and Central America and Australia have been free of the disease for some decades. However, a recent outbreak in Great Britain has placed the world on alert.

A couple of minor addenda.

1. Cattle, sheep, pigs and other infected animals do not die directly from Foot & Mouth disease - rather the blisters which form around the mouth mean they experience such pain through the process of eating that eventually they starve.
2. Foot & Mouth infection vectors are not yet fully researched or understood by the scientific community. It is known that physical carriers - people, vehicles, non-susceptible animal contact - can cause spead of the disease and this is viewed as the major preventable vector. However, given that the droplets containing the virus material are tiny and also relatively long lived, they can, and have, been proven to be carried by wind and exacerbated by precipitation.
3. Only those animals with a cloven hoof are susceptible to Foot & Mouth disease, however non-susceptible animals of all types (including humans) can and do act as transmission vectors for the virus.
4. Although a vaccine is widely available, that vaccine itself has acted as a transmission vector in thousands of cases and is known to increase susceptibility to other viruses such as colds, influenza and others. These effects are proven to be transmissable to humans consuming products from vaccinated animals. The widespread vaccination of farm animals would also lead to those animals acting as non-susceptible carriers, thus making the disease endemic within national herds.

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).

So far about 500 000 animals have been slaughtered in Britain to contain the epidemic, and about 300 000 more are going to be. It might go higher. But this is about the number of deaths that meat-eaters cause in one week.

Also the reason vaccination can only be used as a last resort is that animals could not be exported, because they might harbour the virus and come in contact with unvaccinated animals. If they stayed in Britain they'd be healthy and harmless. They say they have to be slaughtered after they're vaccinated, but that's only because they might still be carriers and so can't be exported. Only when the last possible carrier is dead can the country be declared disease-free.

Where is Britain's meet exported to? Surely not America or Australia or other countries worried about staying disease-free. Haven't they got enough ranches of their own? Within the EU then? So wouldn't it be better if all European countries vaccinated, even if it does have to be every six months or so? Or are the exports to countries where it's more likely to be endemic already? Vaccination is costly, but when a disaster happens, new costly systems are put in to try to prevent it again.

There is not a public health problem. There is not a food supply problem (farms in less than half of England are in danger, and most of Scotland is unaffected). There is not an animal welfare problem (being killed by a bolt gun is their fate anyway). It's an economic problem, and although agriculture is suffering, agriculture's not nearly as important as tourism, which really is being devastated in the worst-affected areas, Devon and the Lake District. It's still safe to go there, just stick to the roads and don't take short-cuts across fields.