Definition Rabies is a fatal nervous system infection that is caused by the rabies virus.
What is going on in the body? The rabies virus is present worldwide, but not in Australia. It can be spread to humans by many different animals. In the US, animal bites from wild animals, such as raccoons, skunks and bats, usually pass the virus on to people. In less developed countries where cats and dogs are not vaccinated against rabies, dog bites are the most common source of rabies. In Australia bat bites or scratches may transmit lyssa virus which is a close relative of the rabies virus. Signs and symptoms, prevention and treatment of lyssa virus exposure and bat bites in Australia are exactly the same as those from rabies.
The rabies virus lives in the saliva of infected animals. It is spread to another animal or a person through a bite or through licking an open wound. In rare cases, people may have breathed in the virus while visiting a heavily infected area, such as a bat cave. In some recent cases of human rabies, there has been no known contact with a bat or other potentially infected animal. This suggests that very little physical contact with an infected animal may be needed to catch the virus in some cases.
What are the signs and symptoms of the infection? Symptoms usually develop within weeks of acquiring the virus. However, symptoms may occur days or even years after the exposure. The symptoms of rabies mainly affect the nervous system and include:
tingling sensations in the area of the animal bite
trouble and pain with swallowing, which may cause a fear of water
loss of consciousness
seizures, which may cause a group of muscles in the body to suddenly shake violently and uncontrollably
What are the causes and risks of the infection? The rabies virus causes the infection. Unless people exposed to the virus are treated promptly, death is almost certain. Treatment rarely helps after symptoms develop.
What can be done to prevent the infection? People should receive treatment to prevent rabies if:
they have been bitten by a rabid or suspected rabid animal, including bats.
they have had close contact with the saliva of a rabid or suspected rabid animal, including bats
they have been bitten by certain wild animals, including bats.
they have a mucous membrane or wound that has come in contact with certain wild animals, including bats.
Prevention of rabies in these cases involves two parts. First, a rabies vaccine is given. Second, a special protein solution, known as rabies-specific immunoglobulin, is given to attack the rabies virus.
People should also vaccinate their cats and dogs to prevent indirect infection with the rabies virus.
How is the infection diagnosed? In order to know if a suspected animal has the virus, the animal is captured and destroyed if possible. Doctors can then examine brain tissue from the animal. To diagnose rabies in a person, a series of special tests are done. These may include tests of the skin, saliva, blood, or spinal fluid.
What are the long-term effects of the infection? The infection almost always causes death if not treated. Even with treatment, death may occur.
What are the risks to others? There is generally no risk to others. In theory, a person with rabies could transmit the infection if they bit someone else.
What are the treatments for the infection? There are no treatments once the infection is established. When exposure to an infected animal is suspected, rabies prevention should be started immediately. Rabies vaccine injections are given the day the person is exposed and on days 3, 7, 14, and 28 after exposure.
How is the infection monitored? If a person is treated before symptoms occur, they are watched carefully to make sure they don't develop rabies. Once symptoms develop, death usually occurs. Treatment can be tried in an intensive care unit, but is generally not successful.
Author: Danielle Zerr, MD Reviewer: HealthAnswers Australia Medical Review Panel Editor: Dr David Taylor, Chief Medical Officer HealthAnswers Australia Last Updated: 1/10/2001 Contributors Potential conflict of interest information for reviewers available on request
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