Rabies

Published by Bupa's Health Information Team, September 2010.

This factsheet is for people who would like information about rabies.

Rabies is a viral infection that can be spread from animals to people. People usually catch it after being bitten by an infected animal, often a dog. Rabies is fatal once the symptoms develop, but can be prevented by vaccination if it's given soon after exposure.

About rabies

Rabies is a viral infection that can only be spread from mammals (warm-blooded animals) to humans. It's most commonly passed on from infected dogs, but you can also get it from raccoons, bats, foxes and skunks.

Rabies causes inflammation of your brain and spinal cord. Unless treated before the symptoms develop, it's almost always fatal. Up to 70,000 people die from rabies every year. The vast majority of these deaths occur in rural areas of developing countries, especially in Africa, Asia and South America.

Since the early 1900s, the rabies virus has been wiped out among wild animals in the UK. Under UK law, most mammals brought into the country that are capable of carrying the rabies virus are required to stay in quarantine for a period of six months before being released. This is to prevent the spread of the virus.

Symptoms of rabies

The time it takes for symptoms to appear after you become infected with the rabies virus is known as the incubation period. This period is usually between one and three months. However, it can be as short as a few weeks, or rarely as long as 19 years. The closer the bite is to your head or spinal cord, the shorter the incubation period is likely to be. You may also develop symptoms faster if you're bitten a number of times, or if your wounds are large and deep.

To begin with, you may have itching, pain or pins and needles in and around the area that has been bitten. You may then develop a flu-like illness with a cough, sore throat, fever and headache, and feel sick or vomit. These symptoms usually last between two and 10 days.

If left untreated, rabies can develop in one of two ways depending on where you get bitten.

Furious rabies

Most people (about four in five) who don't seek treatment for rabies develop the furious form. It causes inflammation of your brain (encephalitis), which leads to a number of different symptoms. If you have furious rabies, you may:

• feel restless or agitated
• feel confused and hallucinate (see or hear things that aren't really there)
• become hyperactive (feeling a need to move all the time)
• have strange thoughts and behave out of character
• become very sensitive to light, noise and touch (hyperaesthesia)
• have difficulty sleeping (insomnia)
• salivate excessively (hypersalivation)

After several hours or days, your symptoms may seem to come and go and be broken up by periods of calmness, normal thoughts and behaviour. However, the time between these episodes will become shorter as the virus spreads throughout your nervous system. About half of all people who have furious rabies develop a fear of water (hydrophobia). This usually begins with a severe pain in your throat and stomach when you try to drink a liquid. The muscles in your neck and stomach may start to contract involuntarily, making you unable to swallow. This, together with the increased salivation, can cause you to 'foam at the mouth', which is a characteristic sign of rabies.

Dumb rabies

Those people who don't seek treatment for rabies and who don't develop the symptoms of the furious form, may develop dumb rabies. Dumb rabies affects your spinal cord and causes muscle paralysis.

The paralysis usually starts near to where you were bitten and then spreads to other areas of your body. You may also develop involuntary muscle twitches, lose control over the movement in your legs and become incontinent (when you're unable to control your bowels or bladder).

Without urgent medical treatment for furious or dumb rabies, you will eventually fall into a coma. Your breathing will slow and your heart will beat irregularly. At this stage, you're very unlikely to recover from the disease. It's almost always fatal within 14 days of going into a coma.

Causes of rabies

The rabies virus belongs to a group of viruses called Lyssavirus. There are ten rabies-like virus strains in this group. The strain known as classical rabies causes the disease in humans. The other strains are rarely passed on from infected animals to humans.

If you get bitten by an infected (rabid) animal, the rabies virus can pass from its saliva, through the wound in your skin and into your body. It's also possible to become infected by absorbing the virus through your eyes, nose or mouth. For instance, if you breathe in saliva from an infected animal, but this is very rare.

Once the rabies virus gets into your body, it incubates for a time before it enters nearby nerves. From here, it gradually travels towards your brain and spinal cord. Once the virus has reached your brain or spinal cord, it spreads throughout the rest of your nervous system very quickly. The virus also enters tissues next to nerves; for example, your salivary glands. This is how it gets into saliva and is the reason why rabies can be spread by bites.

It's very important to seek urgent medical attention when you've been bitten by a rabid animal. This is because the disease can only be treated successfully before symptoms develop.

Diagnosis of rabies

If you've been bitten by an animal, particularly a wild dog or bat, but haven't developed any symptoms of rabies, your GP will give you a tetanus injection. You may also be asked questions about the animal to find out if it was rabid, so that your GP can rule out other diagnoses. This is because rabies is a very rare condition in the UK and your GP may need to refer you to an infectious diseases specialist for further advice and treatment.

To confirm a diagnosis, you may be asked for saliva, urine and blood samples. You may also have a small skin sample taken (a biopsy), usually from your neck. This is to look for antibodies to the virus and confirm whether you have rabies or not.

In the early stages of the disease, it's very difficult to distinguish the symptoms of rabies from other illnesses that cause inflammation of your brain and spinal cord. This is why it's very important to let your GP know if you've been bitten by an animal, even if it was a long time ago.

Treatment of rabies

If you've been bitten and seek help quickly (within days of exposure), it's possible to prevent the disease from developing with an anti-rabies vaccine (see Prevention). However, if you've already developed the symptoms of rabies, there isn't a cure. In this situation, you will need to go to hospital. Your doctor or nurse may give you a sedative and some painkillers to make you feel more comfortable. However, these treatments are only supportive as the disease will be fatal at this stage.

Prevention of rabies

Before exposure to the rabies virus

If you're travelling to an area where rabies is common, you may need to have a pre-exposure vaccine. You will be given three injections. After the first, you will have the second a week later and the third after a further three weeks (or after a further two weeks if there isn't enough time before you travel). After this, you will need a reinforcing dose a year later and a top-up every two to five years, depending on how much you' re at risk of getting rabies.

Having the rabies vaccine doesn't mean you're immune to the disease. However, in the event that you get bitten, it may give you more time to seek medical treatment before the symptoms develop.

See your GP or visit a travel advice centre for more information.

After exposure to the rabies virus

If you've been bitten by an animal that may have rabies, you should clean the wound with soap and water immediately. Then, you should disinfect the area with alcohol or iodine solution and seek help from a medical professional. Your doctor will give you an injection of the rabies vaccine, some antibiotics and a dose of rabies immunoglobulin, depending on the type of animal you've been bitten by.

Afterwards, you will need four further doses of the rabies vaccine; three, seven, 14 and 28 days after exposure. If you had a rabies vaccine before exposure to the virus, you may only need to have two more doses, three days apart.

For answers to frequently asked questions on this topic, see Common questions.

For sources and links to further information, see Resources.