Travellers

Travel Health Information Sheets

Rabies

Introduction

The rabies virus is a species of the genus Lyssavirus, of the family Rhabdoviridae, or bullet-shaped viruses. The virus attacks the central nervous system, causing progressive paralysis, encephalitis and coma. Once symptoms present, rabies is a fatal infection. Although rabies occurs primarily in warm-blooded animals (both domestic and wild), it can be transmitted to man, usually by a bite from an infected animal.

Epidemiology

Data from the Travel Health Surveillance Section of the Health Protection Agency Communicable Disease Surveillance Centre

Global Epidemiology
Rabies Epidemiology
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According to WHO data, 2.5 billion people are at risk of acquiring rabies in more than 100 countries that report the disease [1]. Most parts of the African and Asian continents and many parts of South America are endemic for rabies. An estimated 10 million people worldwide receive post-exposure treatments each year after being bitten by a suspected rabid animal, usually a dog. The UK and most of Western Europe are rabies free due to the success of co-ordinated wildlife oral vaccination programmes, together with the availability of effective commercial vaccination for domestic animals [2]. However, rabies is endemic in wild animals of North America and in the forests of North Eastern Europe. The annual number of deaths worldwide caused by rabies is estimated to be between 50,000 and 60,000; accurate data on the worldwide incidence of rabies is scarce. More than half of the deaths occur in India and Bangladesh, but the true disease burden of rabies is thought to be largely under-estimated especially in Africa. The vast majority (95-98%) of these deaths worldwide occur in canine-endemic regions where large stray dog populations are ineffectively controlled. This combined with limited availability of human post-exposure prophylaxis in some countries; contribute to the high mortality rates [1].

Epidemiology of Rabies in UK Travellers

The last case of indigenous terrestrial animal rabies that occurred in Great Britain was in 1922, and the last recorded case of indigenous terrestrial animal rabies outside quarantine occurred in 1969 and 1970 when two imported dogs died soon after completing 6 months quarantine. Since then, most cases of rabies in the UK have only occurred in quarantined animals or in people infected abroad. The exception is a case of human rabies in a bat handler infected with European Bat Lyssavirus 2 (EBL2) in Scotland in 2002 [3]. Before that incident, a bat infected with EBL2 was discovered in Lancashire earlier in 2002. Another bat of unknown country of origin infected with EBL2 was found in Newhaven, Sussex in 1996. At that time it was thought to have come from another country, for example flown across the channel from France, but in2003, it was recognised that UK bats may now carry EBL2. Rabies is very poorly reported and under-notified in the UK. Since 1902, there have been at least 24 deaths from imported classical rabies reported in the UK. All but two of these resulted from a dog bite (one was from a cat and the other exposure was unknown) and 63% of deaths were after an exposure in the Indian Sub-Continent. The most recent imported cases occurred in 2001. One in an overseas visitor from Nigeria, who had sustained a dog bite on the lower leg five months previously, and the other, a UK resident of Filipino origin who had also been bitten by a dog whilst in the Philippines [4]. None of these cases that have occurred in the UK were known to have received pre-or post-exposure prophylaxis.

Risk for Travellers

It has been estimated that rabies kills between 40,000 and 70,000 people each year worldwide [5]. Most of these deaths occur in Asia, Africa and Latin America, and follow a dog-bite from an infected animal. All these regions have large stray dog populations that pose a significant disease risk to humans. Other mammalian vectors in these countries include bats, monkeys, mongoose and jackal.

In North America and Europe the disease is mainly confined to wild animals (particularly bats, racoons, foxes, coyote and skunks) but human cases have occurred; in North America these have usually followed exposure to an infected bat.

Transmission

Rabies virus is found in the saliva of an infected animal. The virus can be transmitted to humans by a bite or scratch, or when saliva from an infected animal has come into contact with broken skin or mucous membranes (eyes, nose or mouth tissues). Rarely, the virus has been contracted following laboratory exposure or inhalation of infected aerosol in bat caves.

Signs and Symptoms

The incubation period of rabies is between 20 and 90 days, although in rare cases it can be as short as a few days or as long as several years. The prodrome can be a non-specific illness involving symptoms of fever, headache, myalgia and fatigue. Parasthesiae may occur at the site of the bite. The disease progresses to the more common furious rabies, or less common paralytic or 'dumb' rabies.

Furious rabies is characterised by laryngeal spasms, which occur in response to attempts to drink water; these can be accompanied by a feeling of terror. Following further deterioration, coma and death eventually ensue over several days.

The paralytic form of rabies can often be misdiagnosed. Parasthesiae and weakness often first occur around the bite site and begin to ascend. This paralysis results in respiratory failure and inability to swallow, death usually occurs within 1-3 weeks.

Treatment

All travellers who have possibly been exposed to the rabies virus, whether by bites, scratches or other exposure, should seek medical advice without delay. This also applies to travellers in low risk areas as other infections may be present, or the animal may have strayed across the border from an endemic country. Medical advice should be sought without delay even if pre-exposure vaccine was received.

Although a few patients are claimed to have survived rabies, the disease is considered to have a fatal outcome once symptoms manifest themselves.

Prevention

Contact with wild or domestic animals during travel should be avoided.

  • Do not attempt to pick up an unusually tame, unfamiliar animal
  • Do not attract stray animals by being careless with litter

Pre-exposure vaccine should be considered for those travellers at particular risk.

This first aid advice should be given to travellers in the case of a possible exposure to rabies virus. Receiving rabies vaccine prior to travel does not preclude the need for post-exposure medical evaluation and additional doses of rabies vaccine.

  • Immediately wash the wound with soap and running water for 5 minutes.
  • If possible apply an iodine solution or 40-50% alcohol (whiskey or other spirit can be used)
  • Seek medical advice about the need for rabies vaccination and possible antibiotics for a bite wound infection as soon as possible. Tetanus vaccine may also be required, if the traveller is not up-to-date.

References

1. World Health Organization. State of the art of new vaccines: research & development. April 2003. WHO: Geneva. Available online at http://www.who.int/vaccine_research/documents/en/

2. Department of Health. Memorandum on Rabies Prevention and Control. February 2000.

3. Crowcroft NS. Rabies-like infection in Scotland. Eurosurveillance 2002; 6 http://www.eurosurveillance.org/ew/2002/021212.asp

4. CDSC. Rabies acquired abroad. Communicable Disease Report Weekly 2001; 11 (24) http://www2.ncid.cdc.gov/travel/yb/utils/ybGet.asp?section=di

s&obj=rabies.htm

5. World Health Organisation. Rabies fact sheet no. 99. 2001 http://www.who.int/mediacentre/factsheets/fs099/en/index.html

Reading List

CDC http://www2.ncid.cdc.gov/travel/yb/utils/ybGet.asp?section=dis&o

bj=rabies.htm

WHO http://whqlibdoc.who.int/publications/2005/9241580364_ch ap5.pdf

WHO Rabnet http://www.who.int/globalatlas/default.asp