Rabies is an encephalitis caused by rabies virus, a member of the rhabdovirus family. Worldwide, it is estimated that there are in excess of 55,000 cases of classical rabies each year, almost entirely in developing countries.
How common is rabies in animals?
Although in the UK rabies has been eliminated from the animal population, it continues to infect a variety of mammals in many parts of the world, partcicularly in Asia and Africa. (See also the rabies country listing). Dogs and cats, due to their high level of contact with the human population and propensity to bite, are the main risk to humans. People who are travelling should consult their GP or a travel clinic about whether they need rabies vaccination for their itinerary. When abroad in a country where rabies exists it is vital to seek advice immediately following any animal bites or scratches. (see What should travellers do)
The last rabid terrestrial animal in the UK was a puppy in quarantine which had been imported from Sri Lanka and found to be rabid in 2008. Rabies affects bats as well as terrestrial animals, and twice in the last few years rabies-like viruses have been found in bats in the UK. These viruses are known as European Bat Lyssaviruses (EBLVs), very rarely cross the species barrier from bats to humans, and are different from the 'classical' rabies virus found in dogs and other animals. EBLVs are found more commonly in bats elsewhere in Europe than the UK. There have only been four documented cases of transmission of EBLs to humans in Europe from bats in the last 25 or more years.
How common is rabies in humans?
Human rabies is extremely rare in the UK, however, more than 55,000 cases occur worldwide each year. The last case of classical rabies acquired in this country was more than a century ago, in 1902. Cases occurring since then have all been acquired abroad, usually through dog bites. In 2002 a man who was a licensed bat handler died in Scotland from infection with European Bat Lyssavirus 2, a rabies-like virus. This does not alter the status of the UK as rabies-free. On rare occasions someone who is incubating rabies arrives in this country and then falls ill with the disease.
How many cases of rabies have there been in the UK?
Since 1946, twenty-five cases have been reported in the United Kingdom, all imported. Until the case reported in May 2012, only 4 cases had occurred since 2000. Two unconnected cases occurred in 2001, imported from the Philippines and Nigeria (CDR Weekly 11 May 2001 , CDR Weekly 14 June 2001 ). A case in 2005 followed a dog-bite in Goa (Eurosurveillance, 28 July 2005 ), and a case in December 2008 followed a dog bite in South Africa (Health Protection Report, 19 December 2008). The most recent case was in 2012, and was acquired in India.
A case of rabies-like infection caused by a Bat Lyssavirus occurred in Scotland in November 2002 (CDR Weekly 28 November 2002 ).
How do humans catch rabies?
Humans generally catch rabies through being bitten by an infected animal (usually a dog). In this country, rabies has long been eliminated in the animal population, so recent human cases in the UK have all been associated with exposure to infected animals elsewhere in the world.
There are no laboratory-documented cases of human-to-human spread, except by the artificial route of organ transplantation. In a corneal transplant, a part of the cornea is surgically removed after death and grafted into the eye of another person. Once the rabies risk from this was recognised, screening protocols were introduced and there have been no reports of rabies transmission by corneal transplant for over 15 years. The acquisition of rabies following transplantation of solid organs was first described in 2004. Three cases in the United States followed transplantation of organs from a donor who was later discovered to have had rabies. Later that same year, a similar incident occurred in Germany where the donor had probably been infected while travelling in India ( CDR Weekly 3 March 2005 ). In March 2013, a further case of rabies from organ transplantation was reported in the USA.
Is rabies spread from person to person?
Despite there being tens of thousands of rabies cases each year worldwide, there has never been a laboratory-documented case of human-to-human transmission, other than the very few cases resulting from organ transplant (see above). Despite the lack of evidence for human-to-human transmission, people who have been exposed closely to the secretions of a patient with rabies will sometimes be offered immunisation purely as a precautionary measure.
Can rabies be spread by kissing or intimate contact?
This theoretical route of transmission has never been laboratory confirmed. There is no laboratory confirmed documented case of human-to-human transmission of rabies, except for the very small number of cases which have followed organ transplantation from unrecognised rabies cases. However, rabies virus can be found in saliva and other clinical specimens after the onset of rabies symptoms and clinical disease, so there is a small theoretical risk of infection at this stage of disease. This is why post exposure treatment is offered to close contacts of rabies cases.
What are the symptoms and signs of rabies in humans?
Rabies is a very serious infection which affects the central nervous system. It can be difficult to diagnose in the early stages as symptoms may be non-specific (i.e. common to many infections). Initial symptoms can include anxiety, headaches and fever, and later on the effects of the encephalitis intensify. There are spasms of the swallowing muscles making it difficult or impossible for patients to drink (hydrophobia), and respiratory failure sets in.
How long is the incubation period?
The incubation period from the bite to onset of symptoms is generally between 2 to 8 weeks, but is very variable. In some cases, incubation periods have been several months or even years.
How dangerous is rabies?
Rabies is a fatal condition but it is preventable by vaccination. Post-exposure prophylaxis (PEP) is extremely effective at preventing rabies after being bitten, even when this is given some time after an exposure. It is important for people who are at risk through their work or through travelling to countries where rabies is circulating in animals to seek advice on vaccination. Once clinical rabies develops, it is almost always fatal. Those few people who have survived the infection have suffered serious long-term disability.
Who should be protected by immunisation?
Professionals can find advice in the Health Protection Agency's Immunoglobulin Handbook ( http://www.hpa.org.uk/infections/topics_az/immunoglobulin/menu.htm) and in the Department of Health "Green Book"
What can be done to treat rabies?
Rabies must be prevented, because there is no treatment. This means that people should seek advice about vaccination before they travel if going to developing countries where rabies is present. When travelling they should steer clear of animals in general, but particularly stray or unattended dogs. Anyone who is bitten or scratched by a warm blooded animal such as a dog, cat or bat in a country where there is rabies should get advice immediately as rabies vaccine can be given to protect them. It works best if given as soon as possible (see below What should travellers do ?).
Within the UK, if someone is bitten by a bat they should seek medical attention as soon as possible. Expert advice for doctors is available through the Health Protection Agency. They can then be advised on whether they need any preventative treatment. All bat handlers whether licensed or not should be vaccinated preventatively against rabies. If a person has rabies there is no specific treatment currently recommended.
What measures are taken to prevent animals with rabies from entering the country?
The UK eliminated rabies from its terrestrial animal population early in the 20th century. It maintains this by requiring immunisation in vulnerable animals coming into the country and applying quarantine laws to unimmunised animals. Further questions about this should be directed to the Department for the Environment and Rural Affairs (DEFRA), which regulates quarantine legislation ( http://www.defra.gov.uk/).
(page reviewed 18 March 2013)