Health Professionals

Travel Health Information Sheets

April 2007

Rabies

Introduction

Rabies virus is a member 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.

Rabies occurs primarily in warm-blooded animals (both domestic and wild) and is transmitted to man, usually by a bite from an infected animal.

Epidemiology

Global Epidemiology

Rabies Epidemiology 2005.

 

Map courtesy World Health Organization (International Travel and Health, 2007).

Click here for a larger version of the map (opens in a new window 97.3KB PDF)

According to World Health Organization (WHO) data, more than 3 billion people are at risk of acquiring rabies in at least 85 countries worldwide [1].  Most parts of the African and Asian continents and many parts of Latin 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 [1].

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 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 underestimated especially in Africa.  The vast majority (95-98%) of the deaths worldwide occur in regions where stray dog populations are ineffectively controlled. This, combined with limited availability of human post-exposure prophylaxis in many countries, contributes to the high mortality rates [1].

The UK is considered free of rabies in terrestrial animals; cases of rabies in bats are, however, occasionally reported. Most of western Europe is 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, there may be incidents involving imported animals, such as the rabid dog imported into south western France from North Africa in 2004 [3]. Rabies is endemic in wild animals of North America and in the forests of eastern Europe.

Rabies in UK Travellers

The last case of indigenous terrestrial animal rabies occurred in Great Britain in 1922.  The last recorded cases of animal rabies outside quarantine occurred in 1969 and 1970 when two imported dogs died soon after completing six months quarantine.  Since then, nearly all cases of rabies in the UK have occurred in quarantined animals or in people who were 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 [4]. It is now recognised that UK bats may carry EBL2.  More recently, a rabid bat was found in Surrey in 2004 and another in Oxfordshire in 2006 [5].

Since 1902 there have been 24 human deaths in the UK from imported rabies.  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.  Since 2001 there have been three cases of imported human rabies in the UK: an overseas visitor from Nigeria who sustained a dog bite on the lower leg five months prior to clinical symptoms; a UK resident of Filipino origin who had been bitten by a dog whilst in the Philippines [6]; and a British woman who sustained a dog bite during a two week holiday to Goa, India and died of rabies in the UK in 2005 [7].  None of these cases were known to have received pre-or post-exposure prophylaxis.

Risk for Travellers

It is estimated that rabies kills between 50,000 and 60,000 people each year worldwide [1]. Most of these deaths occur in Asia, Africa and Latin America, and follow a bite from an infected dog.  Each of these regions have large stray dog populations that pose a disease risk to humans if they are bitten or have other trans-cutaneous or mucosal exposure to infected saliva.  Other mammalian vectors of rabies 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 human cases 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 following the transplantation of organs from an infected individual [8,9].

    

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 is often non-specific with symptoms of fever, headache, myalgia, and fatigue. Paresthesiae may occur at the site of the bite.  The disease progresses to the more common furious rabies, or the 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 deterioration, coma and death ensue over several days.

The paralytic form of rabies is often misdiagnosed. Paresthesiae and weakness often first occur around the bite site and begin to ascend the bitten limb. The 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. Seeking medical care also applies to travellers in areas considered low risk for rabies as other infections may be transmitted by the bite, or the animal may have been imported or crossed the border from an endemic country [10]. Medical advice should be sought without delay even if pre-exposure vaccine was received.

Although a few patients have survived rabies [11], 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. Travellers should be advised:

  • Not to approach animals.
  • Not to attempt to pick up an unusually tame animal or any animal that appears to be unwell.
  • Not to attract stray animals by offering food or by being careless with litter.
  • To be aware that certain activities may attract dogs (e.g. running, cycling).

Pre-exposure vaccine should be given to travellers at risk. A record of vaccination should be carried and shown to those administering emergency treatment in a post-exposure situation

Receiving rabies vaccine prior to travel does not preclude the need for post-exposure medical evaluation and additional doses of rabies vaccine.

Advice should be given to all travellers regarding first aid in the case of a possible exposure to rabies virus.

Immediately wash the wound with soap and running water for 5 minutes [12,13].

If possible apply an iodine solution (tincture or aqueous solution of povodone-iodine) or quarterly ammonium compounds e.g. cetrimide solution 0.15% or 40-70% alcohol [12,13].

Seek immediate medical advice about the need for rabies vaccination and possible antibiotics to prevent a bite wound infection as soon as possible. Tetanus vaccine may be required if the traveller is not up-to-date.

Rabies Pre-Exposure Vaccine

Indications for use of vaccine

The need for pre-exposure rabies vaccine includes an assessment of:

  • The incidence of rabies in the destination countries [14].
  • The availability and quality of rabies vaccine and rabies immune globulin (RIG) [14].
  • The planned activities of the traveller.
  • The duration of stay.
  • The possibility of unrecognised or unreported exposure (e.g. in young children).

Rabies pre-exposure vaccine should be given to:

  • Those travelling for a month or more in enzootic areas. 
  • Persons who will be travelling for less than a month in enzootic areas, but who may be exposed because of their travel activities.
  • Those at occupational risk e.g. vets, animal handlers, laboratory workers who handle the virus.

Other specific indications for vaccination can be found in Immunisation against Infectious Disease [13].

The rationale for receiving pre-exposure vaccine is that it gives the individual time to reach medical treatment in the event of an animal bite or scratch; or possibly will protect an individual who has an unapparent exposure. Those who have received a pre-exposure course of rabies vaccine will only require two further doses of vaccine post-exposure (according to UK schedules), rather the full course of five vaccines.  In addition, rabies immune globulin (RIG) will not be required.  

Accessing safe and effective rabies vaccine products in resource poor countries may be difficult, and vaccine derived from animal brain tissue may be the only type available. In some areas modern tissue culture rabies vaccines may only be obtained privately or in rabies treatment centres.  RIG is frequently difficult to locate and may only be available in major cities [14].

Travellers should be advised to perform first aid treatment on a wound and to seek medical advice as soon as possible.

Availability of vaccine (in the UK)

There are two rabies vaccines licensed for use in the UK, both of which are inactivated.

Details are found in the Table by clicking here (opens in a new window 61.7KB PDF)

It is good practice to continue a course of rabies with the same brand of vaccine. However, should this not be possible the vaccines may be used interchangeably.

 Intradermal route of administration

The intradermal route is not licensed in the UK for any rabies vaccine and is not recommended.

Interrupted courses

Ideally, those at risk should receive primary pre-exposure vaccination with three doses of inactivated rabies vaccine before travel.  A 0, 7 and 21 day schedule can be given where there is less than four weeks before departure [13]. 

If there are time constraints to the full pre-exposure course, a single dose is likely to prime the immune system.

It is important that travellers understand that if less than the recommended three doses of vaccine have been administered pre-exposure, in the event of a possible exposure, a full post-exposure course of vaccine will be necessary. However, RIG will not usually be necessary.

Expert advice may be required for individuals who have previously received an interrupted or incomplete course of vaccine and who are travelling to an area where they may be at risk.

Contraindications

  • Acute febrile or other infectious illness.
  • Allergy to any constituent of the vaccine.
  • Individuals who develop symptoms suggestive of hypersensitivity after vaccination should not receive further doses of the same vaccine.
  • Rabipur vaccine is propagated on chick cell embryo, and is therefore contraindicated for those with have a known anaphylaxis to egg.

Adverse events

 Adverse events to rabies vaccine tend to be mild and transient and include itching, pain, and erythema at the injection site.  Less commonly fever, malaise, headaches, dizziness, and urticaria can occur.  An immune-complex reaction (serum sickness) of urticaria, pruritis and malaise may occur in about 6% of persons receiving booster doses of HDCV [15].

Post exposure prophylaxis

 Advice regarding post-exposure prophylaxis should be sought from the Health Protection Agency (HPA) Virus Reference Division, Colindale on 020 8200 4400.

If they are not available, the duty doctor at the HPA Centre for Infections should be consulted (020 8200 6868).

Information on rabies post-exposure management is available from the Department of Health [12].

References

1. World Health Organization.  State of the art of new vaccines: research & development.  January 2006. who/ivb/06.01. WHO: Geneva. Accessed 31.10.2006. Available at: http://www.who.int/vaccines-documents/DocsPDF06/814.pdf

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

3. HPA. Rabid dog in south west France. Commun Dis Rep (CDR) Weekly [serial online] 2004 ; 14 (36). Available at : http://www.hpa.org.uk/cdr/archives/2004/cdr3604.pdf

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

5. CDSC. Bat infected with a rabies-like virus in south-east of England. Communicable Disease Report Weekly. 2006;16.(43). Available at: http://www.hpa.org.uk/cdr/archives/archive04/news/news4004.

htm#bat

6. CDSC.  Rabies acquired abroad.  Communicable Disease Report Weekly 2001;11 (24).

7. Solomon T. Marston D. Mallewa M et al. Paralytic rabies after a two week holiday in India. BMJ. 2005;331:501-03

8. Srinvarsan A. Burton EC. Kuehnert MJ et al.Transmission of rabies virus from an organ donor to four transplant recipients. N Engl J Med. 2005;352:1103-11.

9. Hellenbrand W. Meyer C. Rasch G.Cases of rabies in Germany following organ transplantation. EuroSurveill. 2005;10(2):E050224.6.

10. Health Protection Agency.  Rabid dog in south west France. Commun Dis Rep CDR Wkly [serial online] 2004 [cited 2 Jan 2007]; 14(36): news.  Available at: http://www.hpa.org.uk/cdr/archives/2004/cdr3604.pdf

11. Centers for Disease Control and Prevention. Recovery of a patient from clinical rabies--Wisconsin, 2004. MMWR Morb Mortal Wkly Rep 2004;53:1171-3.

12. World Health Organization. Rabies factsheet no.99. 2006.  Available at: http://www.who.int/mediacentre/factsheets/fs099/en/

13. Department of Health. Rabies. Chapter 27 (draft chapter, August 2006) in: Immunisation against infectious disease. 2006.

14. Meslin FX. Rabies as a traveler's risk, especially in high-endemicity areas. J Travel Med 2005;12 Suppl 1:S30-40.

Fishbein DB, Yenne KM, Dreesen DW et al. Risk factors for systemic diploid cell rabies vaccine: a nationwide prospective study. Vaccine 1993; 11:1390-1394

Further reading

Health Protection Agency Centre for Infections. Duty Doctor joint protocol for rabies queries. Updated August 2006. Available at http://www.hpa.org.uk/infections/topics_az/rabies/guidelines.htm

 

World Health Organization. RABNET. Available at http://www.who.int/rabies/rabnet/en/

Links

Rabies Bulletin Europe: http://www.who-rabies-bulletin.org/

Pan American Health Organization, Rabies page: http://www.paho.org/Project.asp?SEL=TP&LNG=ENG&ID=64

World Health Organization, Rabnet: http://www.who.int/globalatlas/default.asp