Rabies

From ArticleWorld

Rabies got its name from the similar Latin word meaning rage. Rabies can occur in almost all warm-blooded animals, although it rarely occurs in non-carnivores.

Rabies is a very dangerous disease and, if occurs in a human who has not received a vaccine, it is almost always fatal. Still, if the vaccine is administrated quickly enough after it has been detected, it may still stop the evolution of the disease.

Causes

The virus is generally encountered in the saliva of an infected animal. The general transmission root is through an animal bite, which is easy to happen since most infected animals are very aggressive. Transmission from human to human is quite rare, but it has been recorded to happen, by organ transplant from an infected donor.

In humans, the virus enters the peripheral nervous system and finds its way to the central nervous system, running along the nerves. As soon as it reaches the brain, it causes encephalitis and the symptoms appear, sometimes associated with myelitis.

Symptoms and treatment

The period between the infection and the moment when the symptoms start to be displayed is usually between 3 and 12 weeks, but it has been reported to last as much as 2 years. The initial symptoms are similar to those of a flu, but later they develop int anxiety, insomnia, confusion, hallucination and abnormal behavior associated with agitation and delirium. The saliva and tears production increase rapidly, associated with difficulties in swallowing.

These symptoms rapidly lead to death, in only 2 to 10 days. Very few people survived without vaccination, and most of them were left with irreversible brain damage. No cure is known for symptomatic rabies, but it can be prevented since the discovery of a vaccine in 1886, by Louis Pasteur. The vaccine as discovered by Pasteur is often used in undeveloped countries, since it is cheaper than the newer developed vaccines.

There is some post-exposure treatment, but it has to be administered very quickly, less than 14 days after the infection. In the US, this PEP consists in five rabies vaccine doses and one dose of immunoglobulin. Post-exposure treatment is generally very efficient, and in most countries rabies is almost eradicated in humans. The only few deadly cases that remain occur due to bat bites which go unnoticed until the symptoms appear.