Rabies

Where it occurs

It can occur anywhere but is particularly prevalent in Asia, the India sub-continent, Central and South America and Africa. There are estimated to be over 10 million infections a year with up to 70,000 deaths.

It is caused by a virus which is spread by the bite of a number of animals - in fact, any warm-blooded mammal can be a carrier. While dogs have traditionally been the main source of rabies in people because they live in proximity to humans, other animals which can become rabid include ferrets, foxes, wolves, raccoons, skunks, coyotes, bears and horses.

In North America, Australia and South America rabies among bats is on the increase and in some recent years more people in South America have died from infection by bats than by dogs.

The effect of the virus on animals is often to make them more aggressive than normal and so more liable to bite - which is when the virus is transferred to the person (or other animal) through the saliva.

The virus travels from the site of the bite via the blood stream into the central nervous system where it replicates swiftly and spreads into the brain. This damages the functioning of both.

Infection

Not everyone who is infected develops symptoms. Where symptoms do appear, this normally takes from three weeks to three months, though it can take much longer.

The illness has two phases. In the first, the patient will usually have a fever, vomiting, loss of appetite, headache and pain at the place where the bite occurred. As the nervous system is affected, symptoms can include excessive salivation and weeping.

In the second more serious phase, sufferers become anxious, confused and delirious. They may lose control of their movements and paralysis can set in, often affecting the throat which makes swallowing difficult.

Death usually occurs within a few days of the symptoms first appearing. The few humans known to have survived have, with one solitary exception, been left with brain damage.

Treatment

It is vital to immediately wash any bite from a potentially rabid animal with soap and water, apply an antiseptic solution and take the victim to hospital. Immunising the sufferer with an anti-rabies vaccination may stimulate the body’s natural defences into action early enough to prevent symptoms developing. However, once symptoms do appear there is no cure, doctors can only try and alleviate the symptoms.