Rabies

What is rabies?

Rabies is a severe viral infection of the brain and spinal cord that is transmitted by infected animals. Human rabies is a disease with almost 100% fatal outcome (death) usually after seven to ten days from the start of the symptoms.

Causes of rabies

Rabies is caused by the rabies virus (lyssavirus family) through a bite or scratch from an infected mammal. The most common species to transmit rabies worldwide are dogs (Africa and Asia) and bats (worldwide), but any infected mammal can potentially transmit rabies. Bats remain an endemic reservoir of rabies-like lyssaviruses in the UK. There is no evidence that rabies is transmitted through the consumption of milk or cooked meat of an infected animal, and rabies cannot be transmitted person-to-person, although very rarely it has been transmitted accidentally by organ transplantation from someone who died from rabies.

Although rabies has been successfully controlled in many parts of the world, about 60,000 people die of rabies world-wide every year, mostly in Asia and Africa. Children are at a high risk as they tend to get in contact with infected animals more frequently.

Symptoms and diagnosis

Symptoms can appear from 20 to 90 days or even longer (up to several years) after the bite/scratch. Early symptoms are often non-specific, mimicking viral infections (e.g. fever, general feeling of unwell, headache). There may be initial pain at the site of the bite, weakness of the affected limb or intense itching beginning at the site of the bite and progressing to involve the limb or side of the face. Other symptoms include intolerance to noise or light, anger and depression.

Two thirds of people infected with the virus then progress to encephalitic rabies (furious rabies), which is characterised by episodes of hyperactivity, hallucinations, agitation, confusion, muscle spasms, altered functioning of the heart, bladder, intestines, sweat glands, pupils, and blood vessels, and hydrophobia (fear of water) with hypersalivation (excessive production of saliva). The remainder develop paralytic rabies with paralysis of the limbs and respiratory muscles. It is not known why some patients develop the encephalitic form and others paralytic rabies.

Rabies is diagnosed by detection of rabies virus (e.g. in samples of saliva, brain tissue or peripheral nerves in the skin), or by the detection of rabies antibody in a non-immunised (vaccinated) patient. Tests are unable to diagnose rabies before the appearance of symptoms.

Treatment of rabies

There is no treatment to cure rabies. In exceptional cases, individuals with rabies have survived with supportive treatment. An experimental regimen known as the Milwaukee protocol (after the hospital which first employed it) was initially reported to cure a patient with bat rabies, but has since failed in a series of cases. Hospital care for rabies encephalitis is supportive, consisting of sedation (for agitation), nutritional support, supplementary fluids and analgesia (for pain).

Prevention of rabies

Rabies is a 100% preventable disease: there is a pre-exposure prevention and a post-exposure prevention.

Rabies vaccine can be given by two routes: intramuscularly (into a muscle) and intradermally (into the skin). The use of the intradermal immunisation regime requires a smaller quantity of vaccine but has equivalent effectiveness. Vaccines are used to prevent the disease both before and after exposure (bite, scratch). Given the lethality of clinical rabies, post-exposure prophylaxis (to prevent the disease) is imperative.

1. Pre-exposure

Pre-exposure prophylaxis is recommended for persons who are at high risk of exposure to rabies because of their occupation (e.g veterinarians, animal handlers, rabies researchers etc), travel or residence in rabies-endemic areas. It comprises of active immunisation with multiple doses of rabies vaccine, over one to four weeks.

Vaccine immunity wanes, so booster vaccination may be needed in people at continuous risk. In the event of exposure to rabies, post-exposure prophylaxis (PEP) with vaccination is still required for those who have received pre-exposure vaccination, but without the need for immunoglobulin.

2. Post-exposure

Rabies can be effectively prevented after a bite through post-exposure prophylaxis (PEP) which comprises:

• wound cleansing,
• active immunisation with multiple doses of rabies vaccine, over one to four weeks and
• passive immunisation with human rabies immunoglobulin injected into the wound and intramuscularly.

Globally, dogs are the overwhelming source of human rabies. Mass vaccination of dogs is the most cost-effective way to eliminate rabies. Rabies elimination remains a significant public health challenge, due to the lack of resources for vaccination programmes and rabies surveillance in endemic regions

Rabies among travellers

Travellers need to be aware of the risk of rabies and take preventive measures which include:

• knowing if the country they visit is endemic.
• vaccination (pre-exposure prophylaxis) before travelling in areas with a high risk (it takes one week to complete the vaccine course).
• avoiding contact with  animals; even a bite from what appears to be a harmless pet must be considered carefully.
• getting information about PEP measures in the area they travel to: where are the closest medical facilities with PEP and what to do in case of a contact with an infected animal.

First Aid in case of a bite recommended by World Health Organisation:

• wash and flush the wound with soap and water for 10- 15 minutes,
• clean the wound  with 70% alcohol/ ethanol or povidone-iodine or a similar antiseptic if available, and
• contact a health care facility immediately.

Other resources

• Global Alliance for Rabies Control (GARC)
• World Health Organisation (WHO) 
• NHS  (Rabies vaccination within UK)

 

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By Alina Ellerington, Encephalitis International and reviewed by Prof Macpherson Mallewa, University of Malawi, Dr Christopher Duncan, Institute of Cellular Medicine, Newcastle and Dr. Reeta S. Mani, NIMHANS, Bangalore, India

FS040V3 Rabies encephalitis

Date created: February 2015; Date updated: October 2021; Review date: October 2024

Disclaimer: We try to ensure that the information is easy to understand, accurate and up-to-date as possible. If you would like more information on the source material and references the author used to write this document please contact the Encephalitis International. None of the authors of the above document has declared any conflict of interest, which may arise from being named as an author of this document.