London School of Hygiene & Tropical Medicine

Following the confirmation of an extremely rare case of rabies in London, Dr Ron Behrens, Senior Lecturer in Tropical and Travel Medicine at the London School of Hygiene and Tropical Medicine, explains the facts about the virus.

What are the symptoms of rabies?

The symptoms of rabies result from inflammation of the brain from the virus.  In the early stages the symptoms are mild, headaches, some anaesthetic feeling around the site of a bite and fever. There is often confusion and delirium - disorientation often associated with abnormal and sometimes violent behaviour.  A unique symptom is that of hydrophobia where the patient has a fear of water - the sound, sight and thought of water causes anxiety and panic.  They are not able to drink or swallow as a result of this.  Ultimately they become comatose during the terminal stages. 

What is the prognosis?

The prognosis is bleak as most patients with rabies encephalitis die.   Only one or two cases are known to have survived the disease. Once the patient has developed encephalitis, the management involves making the patient comfortable by sedation and paralysing them and placing them in an anaesthetic coma.  At this stage none of the vaccines or immunoglobulin has any benefit.

How is rabies contracted?

As there is no animal rabies in the UK the majority of the disease is in developing countries and the main risk animals are dogs. Unfortunately a rabid dog in the early stages does not behave unusually and if licked, scratched or bitten you may have been exposed. The disease can incubate from weeks to years after infection and there may be no signs during this period of infection. If bitten by a rabid dog there is approximately 24 hrs where treatment with rabies immunoglobulin will prevent the virus entering the nervous system. It is recommended that people with pre-exposure vaccination have two boosters after a bite. Unfortunately once the virus is in the nervous system the vaccine and immunoglobulin have minimal effect.

How can people protect themselves from rabies?

Fortunately if you have had a course of three rabies vaccines before you are exposed, known as a pre-exposure course, this will provide life-long protection should you be bitten.  As this is an expensive course of vaccines and the disease in travellers is very rare ( 1 case every 5 -10 years) you need  an experienced healthcare professional to help you decide  whether or not you should receive this course of vaccines. You should avoid coming into contact with any animals in developing countries, even if they belong to someone you know.  No stroking, petting, playing with dogs and cats. 

What treatment is available?

After any animal bite the wound should be washed with an antiseptic and medical advice sought  immediately within 24 hours  to receive vaccine and  rabies immunoglobulin post-exposure treatment. If you are scratched, bitten or licked on an open wound and haven’t received a pre-exposure course you need to find a clinic that has rabies immunoglobulin immediately. This is a very expensive and rare product and most centres outside capital cities and even in capital cities in many countries won't have it available. Immediate assessment at a tropical hospital or similar specialist centre is important if you are exposed to any animal bite. I suggest the course of pre-exposure vaccine be likened to an insurance vaccine against a rare problem. More than 50,000 people every year die from rabies despite there being a very good preventative vaccine for both humans and animals.

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