Rabies - Disease information

Rabies can infect domestic animals, wild animals and humans. Rabies is caused by a virus and transmitted by close contact with saliva from infected animals (ie. bites, scratches, licks on broken skin and mucous membranes). Once symptoms of the disease develop, rabies is fatal.

Rabies can be prevented by vaccination. Rabies vaccine is also curative if given post-exposure before the manifestation of clinical symptoms.

1. Pathogenesis
2. Clinical symptoms
3. Diagnosis
4. Post exposure treatment

Pathogenesis of rabies

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Clinical signs/symptoms

Symptoms of rabies are usually seen 2-8 weeks after contact with a rabid animal. In some cases it can take more than a year before the disease becomes apparent, in these cases the link to the event or cause of infection often cannot be made.

The rabies virus affects central nervous tissue. In the acute stage, signs of hyperactivity (furious rabies) or pareisis (dumb rabies) predominate.

Various neurological symptoms are then seen:

• anxiety
• confusion
• slight or partial paralysis
• excitation
• agitation
• aggression
• hypersalivation
• difficulty swallowing
• hydrophobia (fear of water)

Symptoms usually progress towards paralysis and coma in cases of both furious and dumb rabies. Death usually occurs from respiratory paralysis within days after the onset of symptoms.

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Diagnosis

Laboratory tests are required to confirm the diagnosis of rabies ante-mortally in humans. The most commonly used test in animals is the Direct Fluorescent Antibody (DFA) test. The test is done post mortally on the brain tissue of animals suspected of having rabies. For full details on diagnostic tests for rabies see Manual of Diagnostic Tests and vaccines for terrestrial animals, OIE web site.

Diagnosing rabies in humans
Several laboratory tests are required to confirm a diagnosis of rabies. Saliva, serum, spinal fluid and skin biopsies are all examined and tested for rabies antigen or antibodies.

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Post exposure treatment

The following is carried out after possible or confirmed exposure to rabies infection.

1. Immediate and thorough cleansing of the wound with soap and water is vital.
2. Disinfection of the wound with a suitable disinfectant.
3. Administration of anti-rabies vaccine.
4. The use of immunoglobulins is considered depending on the severity of the wound(s).

For more information see WHO website - Guide for post-exposure prophylaxis

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