Rabies

Symptoms

After the symptoms of rabies appear, the disease is nearly always fatal. The virus damages the central nervous system, which includes the brain and spinal cord.

To prevent rabies, you must get care before symptoms develop. Symptoms in humans may take from several days to more than a year to appear, although most people have signs of disease within 2 to 3 months. Medical care to prevent rabies is advised even if symptoms do not appear soon after exposure to the virus.

Signs in animals

Rabid animals—those infected with rabies—may display noticeable signs or behavioral changes. An animal that has bitten someone and is or was acting strangely may be rabid.

It is important to observe the animal when possible in order to provide proper and timely preventive treatment to any person who may have been exposed. An animal that shows any of the following signs may have rabies:

• No fear of humans shown by a wild animal
• Shyness in a usually friendly pet
• Restlessness, excitability, aggression, or sudden mood changes
• Excessive drooling
• An animal that is normally active at night (such as bats, raccoons, and skunks) being active during the day
• Eating substances not normally eaten (pica)
• Paralysis, which is sometimes the only sign

Symptoms in humans

The typical incubation period for rabies is 2 to 3 months. In rare cases, the incubation period can last from several days to more than a year after exposure to the virus. During the incubation period, there are usually no symptoms of rabies. Early symptoms include pain and numbness at the site of the bite followed by vague symptoms that are often confused with those of other conditions. These include:

• Fever.
• Cough or sore throat.
• Pain, burning, itching, tingling, or numbness at the site of the bite or original exposure.
• Abdominal pain.
• Anxiety or restlessness that gradually gets worse and may become extreme agitation.

Later symptoms are more distinctive and may include:

• Periods of normal behavior that alternate with bizarre or unusual behavior, such as:
  • Anxiety or feeling agitated.
  • Hallucinations.
  • Delirium.
• Fear of water (hydrophobia) or fear of air (aerophobia).
• Muscle spasms in the face, neck, and/or diaphragm, followed by seizures.
• Paralysis, which is often the only symptom of the less common paralytic form of rabies often associated with rabies from vampire bats.
• Wide fluctuations in temperature, pulse, and blood pressure.
• Coma, and heart and respiratory failure.

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Author:	Caroline Rea, RN, BS, MS	Last Updated: September 9, 2008
Medical Review:	William M. Green, MD - Emergency Medicine W. David Colby IV, MSc, MD, FRCPC - Infectious Disease
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