What is rabies?
Rabies is a very serious viral infection that targets the brain and nervous system. You can catch rabies if you are bitten by an infected animal and haven't been vaccinated.
It is almost always fatal unless treated very early.
Rabies is a zoonotic infection, which means it is passed to humans by animals.
You can become infected if the animal's saliva enters your body after it bites you, or after it scratches you when it has licked its paws or claws.
Less commonly, you can become infected if you have a cut or graze that the animal licks.
Most mammals can carry the rabies virus, but the majority of cases result from a dog bite.
In theory, rabies can spread between humans, but the only confirmed human-to-human cases have resulted from organ transplants.
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What are the symptoms?
It can take a while for symptoms to develop, but when they do the condition is almost always fatal.
Symptoms in humans can include:
- tingling and itchiness at the site of infection
- high temperature (fever)
- an irrational fear of water (hydrophobia)
- aggressive behaviour
An animal with rabies may also have some of these symptoms, although some symptoms – such as hydrophobia – only occur in humans.
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When to seek medical help
If you are travelling in, or have recently visited, an area of the world with a high rate of rabies and you are worried you or your child may have been infected, you should seek medical help immediately.
If you know you've been bitten, you should:
- wash the wound thoroughly with soap and water under a running tap
- use antiseptic or alcohol to clean the wound
- leave the wound open
- go to the nearest hospital or medical centre and explain you have been bitten
If there is a high risk that you have rabies in its early stages (before you have any symptoms), you will be given a course of treatment known as post-exposure prophylaxis.
This usually involves cleaning the site of contamination and administering a course of the rabies vaccine in an attempt to prevent the infection spreading to the brain and nervous system. In most cases, post-exposure prophylaxis is effective.
If rabies has reached a stage where it has caused symptoms, it is almost always fatal. In these cases, treatment will usually focus on making you as comfortable as possible.
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A number of vaccines can be used to prevent a rabies infection developing.
Routine vaccination is usually only recommended if you regularly work with potentially infected animals or are travelling to a part of the world known to have high levels of rabies and limited medical care.
Most people going on a standard holiday (as opposed to trekking or living and working in rural areas) will not need a rabies vaccine.
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When travelling in countries that are not rabies-free, do not touch unknown animals and educate your children about the dangers of petting unknown animals. Examine your children regularly for cuts and scratches following contact with any animal and ask how they got them. Make sure they know that being bitten by an animal is dangerous and they need to tell you about it.
Quarantine and the pet travel scheme (PETS)
To keep countries rabies-free, it is important there are strict public health measures to control stray animals, such as foxes. The movement of potentially infected animals across borders into uninfected regions is controlled by strictly enforcing quarantine regulations.
How common is rabies?
There are an estimated 55,000 deaths from rabies each year worldwide. Most cases occur in the developing world, particularly in Africa and Asia.
Symptoms of rabies
The initial symptoms of rabies are mild, but they quickly become serious.
The incubation period
The incubation period is the time it takes for symptoms to develop after a person is infected with the virus. The incubation period for rabies is usually two to 12 weeks, although it can be as short as four days. It would be highly unusual for the incubation period to last for more than a year.
The closer the site of infection is to your brain, the shorter the incubation period. For example, a bite to your face, head or neck will have a shorter incubation period than a bite to your arm or leg.
The length of the incubation period is important because it is the only period in which treatment can be successful.
The initial symptoms of rabies are often vague, and it can be easy to mistake them for other less serious types of infection. They include:
- a high temperature of 38ºC (100.4ºF) or above
- fatigue (extreme tiredness)
- problems sleeping
- lack of appetite
- sore throat
Around half of people will also experience pain and a tingling sensation at the site of the infection.
Initial symptoms of rabies last for two to 10 days before more severe symptoms start to develop. There are two types of advanced rabies:
- furious rabies, which accounts for four out of five cases
- dumb or paralytic rabies, which accounts for the remainder of cases
Furious rabies is characterised by episodes of increasingly odd and hyperactive behaviour, separated by periods of relative calm. During these episodes a person may have some or all of the following signs and symptoms:
- aggressive behaviour, such as thrashing out or biting
- hallucinations – seeing or hearing things that are not real
- delusions – believing things that are obviously untrue
- excessive production of saliva
- high temperature (fever)
- excessive sweating
- the hair on their skin stands up
- a sustained erection (in men)
People with furious rabies will also develop hydrophobia (a fear of water). This initially begins as a pain in the throat or difficulty swallowing. On attempting to swallow, the muscles in the throat go into a brief spasm that lasts for a few seconds. Subsequently the sight, sound or even the mention of water (or any other liquid) can trigger further spasms. There will also be fear of bright light (photophobia) and fear of breezes (aerophobia).
A few days after these symptoms develop, the affected person will fall into a coma and die, usually as a result of heart or lung failure.
Dumb or paralytic rabies
Dumb rabies, sometimes called paralytic rabies, is characterised by muscle weakness, loss of sensation and(inability to move one or more muscles). This usually begins in the hands and feet before spreading throughout the body.
Hydrophobia is unusual in cases of dumb rabies, although muscles may go into spasm. As with furious rabies, someone with dumb rabies will fall into a coma and eventually die from heart or lung failure.
When to seek medical advice
If you are in a part of the world known to be affected by rabies, always seek medical advice as soon as possible if you are bitten or scratched by an animal, particularly a dog. You can also catch rabies if you have an open wound that is licked by an infected animal.
However, always seek medical attention if you are bitten by a bat, or if you suspect someone in your care who is unable to report a bite may have been bitten (for example, if you find a bat in a young child's room).
Symptoms of rabies in an animal
As with humans, the symptoms of rabies in an animal follow a number of stages.
The first stage is marked by initial vague symptoms, such as:
- loss of appetite
- a change in normal behaviour, such as appearing unusually tame around strangers
The second stage is known as the "mad dog" stage and usually lasts for two to four days. It is characterised by aggressive and erratic behaviour, such as:
- constantly barking or growling
- no fear of normal natural enemies
- attempting to attack and bite anything that comes near, including inanimate objects
The final stage, known as the "paralytic" stage, lasts for two to four days and is characterised by symptoms such as:
- the animal appearing to be choking
- foaming at the mouth
- the dropping of the lower jaw (in dogs)
- of the jaw, mouth and throat muscles
Causes of rabies
The rabies virus belongs to a group of viruses called lyssaviruses, which can infect mammals.
The virus is passed on to humans through an infected animal's saliva.
How rabies spreads
Rabies can spread to humans from infected animals through a bite, a scratch, or a lick to broken skin or the eye. You may also be at risk if an animal spits in your face.
Once it enters the body, the rabies virus multiplies before spreading into nerve endings. It then travels to the spinal cord and brain (the central nervous system). Once the virus is in the central nervous system, it will spread to the salivary glands, lungs, kidneys and other organs.
While in theory it is possible for rabies to spread between humans, this has so far only happened as a result of infected donated organs. These human-to-human cases are very rare and have not occurred in the UK.
Animals that carry rabies
All mammals can carry rabies. However, the following species are more commonly infected:
In developing countries, particularly those in Africa and Asia, the majority of rabies cases are caused by dog bites. In South America, bats are also a significant cause.
You should seek immediate medical advice if you are worried you may have been infected by an animal while abroad.
If rabies is suspected, treatment should begin before a diagnosis is confirmed.
This is because any delay in treatment could allow the disease to progress to a fatal stage.
There are currently no tests to identify rabies before it reaches this stage. A diagnosis is based on the likelihood you have the infection – for example, whether you have visited somewhere with high rates of the disease and if you may have been bitten by a potentially infected animal.
Tests used to confirm a diagnosis of rabies in its more advanced stages include:
- skin – a small sample of your skin is removed and checked for the presence of the rabies virus
- saliva test – a sample of your saliva is tested for the presence of the rabies virus
- – a needle is used to remove a small sample of cerebrospinal fluid (CSF), which can be checked for the rabies antibodies (CSF is the fluid that surrounds your brain and spinal cord)
- – your blood is checked for the rabies antibodies
Treatment for rabies
The treatment given for rabies will depend on whether you have started to show signs or symptoms.
If you show no signs or symptoms and it is suspected you may be infected, a course of treatment called post-exposure prophylaxis (PEP) is used. This can usually prevent a rabies infection from becoming established and producing symptoms.
If you have symptoms of rabies, treatment will usually focus on making you as comfortable as possible. This is because rabies is almost always fatal when it reaches this stage.
These two types of treatment are described in more detail below.
Post-exposure prophylaxis consists of three elements:
- cleaning the wound
- administering rabies immunoglobulin – a special preparation of antibodies
- administering a course of the rabies vaccine
Cleaning the wound
Immediately after being bitten, you should:
- wash the wound thoroughly under a running tap
- use antiseptic or alcohol to clean the wound and apply ethanol, tincture or aqueous solution of iodine, if available
- leave the wound open – use a simple dressing but do not try to stitch it, because this could expose your nerve endings to the rabies virus
- go to the nearest hospital or medical centre and explain you have been bitten
If you think your eye may have been infected with the saliva of an animal, you should wash it thoroughly with clean water and seek medical help.
If there is a high risk you are infected with rabies, you should be given an injection of rabies immunoglobulin. This should help protect you against the virus and prevent it travelling to your nervous system.
The immunoglobulin works by providing ready-made antibodies designed to neutralise the rabies virus and prevent it from spreading.
Aside from some temporary soreness at the site of the injection, rabies immunoglobulin does not usually cause any side effects.
The rabies vaccine should be given in every case of suspected exposure to rabies. The length of your course of vaccinations will depend on whether you have previously been vaccinated.
If you have never been vaccinated, you should receive five doses of the vaccine. The first dose is given at the beginning of the treatment, followed by four further doses, which are given three, seven, 14 and 30 days after the start of treatment.
If you have previously been vaccinated, you should receive two doses of the vaccine. The first dose is given at the start of your treatment, followed by a second dose three to seven days later. The doses are given by injection into the shoulder muscle.
A common side effect of the rabies vaccine is redness, swelling and pain at the site of the injection that occurs 24 to 48 hours after the injection has been given.
Choice of vaccine
There are three types of rabies vaccine:
- human diploid cell vaccine (HDCV), which is created by using samples of human cells
- purified chick embryo cell rabies vaccine (PCEC), which is created by using samples of chicken embryos
- nerve tissue vaccine, which is created using samples of nerves taken from animal brains
The World Health Organization (WHO) recommends that only HDCV or PCEC should be used. This is because there are safety concerns over the nerve tissue vaccine. Researchers have found this type of vaccine has a one in a 650 chance of causing serious complications that can result in permanent disability, such as muscle paralysis.
A small number of countries have not followed the WHO recommendation and still use the nerve tissue vaccine. They include Mongolia, Myanmar (Burma) and Pakistan.
In many developing countries, the HDCV or PCEC vaccine may only be available if you are willing to pay for private treatment.
If you are offered the nerve tissue vaccine, it is recommended you refuse and ask for one of the alternative vaccines.
If a person who is infected with rabies is not treated and they have developed symptoms, rabies is said to be established.
In this situation, there is almost nothing that can be done apart from keeping them comfortable. This is usually done by using powerful tranquilisers and sedatives to keep them free from physical pain and emotional upset.
To date, there have been no reported cases of human-to-human transmission of rabies. However, it is theoretically possible, so anyone who has been in close contact with someone who has a rabies infection may be advised to have post-exposure prophylaxis as a precaution.
In very rare cases, established rabies infections have been treated using a technique called the Milwaukee Protocol.
The Milwaukee Protocol
Until recently, all cases of established rabies infection were thought fatal.
However, a technique called the Milwaukee Protocol was attempted in 2004 on a patient with established rabies, and it saved their life. It involves inducing a coma so the person's brain is protected while their immune system tackles the infection.
Since then, the lives of five more people with rabies, none of whom had post-exposure prophylaxis treatment, have been saved using this technique.
However, this technique has only been used about 35 times overall and currently has a low success rate.
It is therefore still considered to be highly experimental and is not widely used.
How to prevent rabies
A vaccination that offers protection against rabies is recommended for people who are felt to be at risk.
Who should be vaccinated?
[Rabies vaccination] can be recommended for:
- laboratory workers who may be required to handle samples of the rabies virus
- people handling bats
- people travelling to an area for one month or more where rabies is common in animals, and where there is no access to prompt and safe medical care
- people travelling to an area where rabies is common and carrying out activities that expose them to rabies, such as trekking in a jungle
- people working abroad in close contact with animals, such as vets or animal handlers at zoos
Vaccination usually requires a course of three doses for protection. The second dose is given seven days after the first. The third dose is given 21 or 28 days after the first, depending on which vaccine is used.
The injections are not painful and are given into your upper arm. There are usually no serious side effects.
Vaccination should be completed before your departure to allow your body to develop full immunity.
As a general rule, pregnant women are usually advised to avoid rabies vaccinations. The vaccine is usually only recommended if the potential risk of exposure to rabies is thought to be high and there is limited access to medical care.
For those people who continue to be at risk of rabies exposure (because of their job, for example), further doses of the vaccine are needed to maintain immunity.
If this is the case, a single reinforcing dose of vaccine should be given one year after the first course is completed. Further doses should be given at three- to five-year intervals after that.
Further doses are not usually recommended for travellers, unless it has been more than 10 years since you were first vaccinated and you are visiting an area with a high risk of rabies.
After having the rabies vaccine, some people experience temporary soreness, redness and swelling at the injection site for 24-48 hours after the vaccination. In rare cases, some people may also experience:
- a mild fever
- muscle aches
- a rash
Severe reactions are very rare.