Foot-and-mouth disease

From ArticleWorld

Foot and mouth disease usually affects animals with cloven hooves, such as elephants, rats, and hedgehogs, but not horses. Some cases of humans affected by this disease have been reported. Foot and mouth disease is very contagious and still occurs in many areas of the world, although some some countries (including USA, Canada and Australia) have eradicated it. The disease has seven serotypes- O, A, SAT-1, SAT-2, SAT-3 and Asia-1, with the O serotype being the most common. Foot and mouth is caused by an aphtovirus in the picornaviridae viral family, a 25-30 nm, non-developed icosahedral virus. It is usually transmitted through direct contact.

Symptoms

In cattle, the disease starts with high fever that does, however, disappear after a few days. Excessive secretion of saliva occurs and animals may suffer weight loss, swelling in the testicles of mature males and a decrease of milk production. Most animals recover spontaneously, but those who don't develop myocarditis. Newborn animals are especially exposed to this risk.

In humans, it causes fever, vomiting, lesions of the oral tissue and blisters of the skin. However, it only rarely occurs in humans because it is very sensitive to the acid in the stomach, meaning it cannot be transmitted by food.

Treatment and prevention

The treatment is no different from the one in other viral infections. The immune system can generally fight the virus successfully, and supportive therapy is required only in more severe cases. Several vaccines for the foot-and-mouth disease exist, but vaccination is very difficult, especially because of the great difference between the serotypes. No cross-protection between them is available, and the immunity provided by vaccines is usually short-term. The vaccines themselves are highly simplified since the 1980s, when the US released a vaccine that only used a certain protein from the virus.

The prevention of this disease is of a high economic importance, because countries that have eradicated it to the point where vaccination is no longer required have priority on the export markets.