A case of rabies has been confirmed in the UK, the Health Protection Agency (HPA) said.
The potentially fatal disease was confirmed in a patient from London after they had been bitten by a dog in South Asia.
The patient, whose age or gender was not given, is receiving hospital treatment and all relevant contacts have been followed up, the HPA said.
HPA officials stressed there was no risk to the public. Dr Brian McCloskey, director of the HPA for London, said: "It is important to stress that there is no risk to the general public as a result of this case or to patients and visitors at the hospital where the patient is receiving treatment.
"Despite there being tens of thousands of rabies cases each year worldwide, there have been no documented laboratory confirmed cases of human-to-human spread. Therefore, the risk to other humans or animals from a patient with rabies is considered negligible.
"However, to take every possible precaution, family members and healthcare staff who had close contact with the patient since they became unwell - which is when they are infectious - have been assessed and offered vaccination if appropriate."
Rabies is usually transferred through saliva from the bite of an infected animal, with dogs being the most common transmitter of rabies to humans. More than 55,000 people are estimated to die from rabies every year, with most cases occurring in developing countries, particularly South and South-East Asia.
Professor David Brown, a rabies expert at the HPA, said only four cases of human rabies acquired from dogs have been identified since 2000, all from animals abroad.
He said: "Rabies is an acute viral infection which is extremely rare in the United Kingdom. It is essential to get health advice if you are travelling to countries where rabies is common or if you know you will be working with animals.
"All travellers to a rabies-endemic country should avoid contact with cats, dogs and other animals wherever possible as you cannot be certain that there is no risk."