A rare case of rabies has been confirmed in London, the Health Protection Agency has confirmed.
But how common is the disease worldwide - and how is it being tackled?
What is rabies?
Rabies is a viral infection that affects the nervous system.
It is a zoonotic disease - one passed on to humans from animals. It is transmitted via saliva from infected animals - most commonly dogs.
Bats can also be a source of a rabies-like infection. But deaths after exposure to foxes, racoons, jackals and other wild carnivores are rare.
Rabies is sometimes also known as hydrophobia - because of a symptom which can occur where patients have great difficulty swallowing and are unable to quench their thirst.
- Rabies occurs in more than 150 countries and territories
- More than 55 000 people die of it every year.
- 40% of those bitten are children aged under 15
- Dogs are the source of 99% of human rabies deaths.
- Wound cleaning and immunization within a few hours after contact with a suspect rabid animal can prevent the onset of rabies and death.
- Each year, more than 15m people worldwide are treated after exposure - this is estimated to prevent 327 000 rabies deaths annually
How does it develop?
The incubation period is usually between two and eight weeks - though it can be longer. It affects the central nervous system and initial symptoms include anxiety, headaches and fever.
As it spreads through the central nervous system, progressive and fatal inflammation of the brain and spinal cord develops.
There are two forms of the disease.
The "furious" form develops rapidly. Patients display signs such as hyperactivity and death occurs within days due to respiratory arrest.
"Paralytic" rabies accounts for around 30% of cases. It develops less rapidly. Muscles gradually become paralysed, a coma slowly develops eventually leading to death.
Rabies can only be diagnosed once symptoms have developed.
Can it be passed between people?
There are no documented cases - but those close to someone who is infected will sometimes be offered immunisation as a precaution.
How common is rabies?
There are over 55,000 a year worldwide, with most cases in developing countries, most in south and south-east Asia.
Around 40% of people bitten are children aged under 15 and the majority of those are boys.
Rabies occurs in more than 150 countries and territories, according to the World Health Organization.
It is extremely rare in the UK. There have only been four deaths since 2000 - all in people who were bitten by dogs abroad.
The last case where someone was infected in the UK occurred in 1922, the last death from indigenous rabies was in 1902.
In 2003, it was recognised UK bats may carry a rabies-like virus. A man who worked as a bat-handler died from the infection, which was probably acquired in Scotland.
Why is there no rabies in the UK?
Rabies was eliminated from domestic animals in the US and UK during the middle of the last century.
Dogs, cats, ferrets and other susceptible animals that have not been vaccinated against rabies are required to remain in quarantine for six months before they can enter the UK, in order to keep the UK rabies-free.
An awareness campaign in the 1980s also warned the public to steer clear of animals when they were abroad - and not to bring them back to the UK.
What is the advice if someone is going to a country where rabies is present?
Talk to your doctor or nurse about whether or not you need to be vaccinated.
Avoid contact with dogs, cats and other animals wherever possible.
If you are bitten, scratched or licked by a warm-blooded animal was the affected area immediately with plenty of soap and water and seek medical advice without delay.
You may be given the rabies vaccine as it is still effective even if given some time after exposure.
Can it be controlled?
The WHO says the best way of preventing human infection is to eliminate rabies infections in animals through vaccination.