Rabies

Rabies (from a Latin word meaning rage) is a viral disease that causes acute encephalitis in animals and people. It can affect most species of warm-blooded animals, but is rare among non-carnivores. In unvaccinated humans, rabies is almost invariably fatal once full-blown symptoms have developed, but post-exposure vaccination can prevent symptoms from developing.

Prevention

There is no known cure for symptomatic rabies, but it can be prevented by vaccination, both in humans and other animals. Virtually every infection with rabies was historically a death sentence, until Louis Pasteur developed the first rabies vaccination in 1886. Pasteur demonstrated its effectiveness by treating Joseph Meister, who had been bitten by a rabid dog.

Related Topics:
Vaccination - Louis Pasteur - 1886 - Joseph Meister

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Pasteur's vaccine consisted of a sample of the virus harvested from infected (and necessarily dead) rabbits, which was weakened by allowing it to dry. Similar nerve tissue-derived vaccines are still used today in developing countries, and while they are much cheaper than modern cell-culture vaccines, they are not as effective and carry a certain risk of neurological complications.

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Treatment after exposure (known as post-exposure prophylaxis or "PEP") is highly successful in preventing the disease if administered promptly, within 14 days after infection. In the United States, the treatment consists of a regimen of one dose of immunoglobulin and five doses of rabies vaccine over a 28-day period. Rabies immunoglobulin and the first dose of rabies vaccine should be given as soon as possible after exposure, with additional doses on days 3, 7, 14, and 28 after the first. The vaccinations are relatively painless and are given in one's arm, in contrast to previous treatments which were given through a large needle inserted into the abdomen. In case of animal bites it is also helpful to remove, by thorough washing, as much infectious material as soon as possible. Since the development of effective human vaccines and immunoglobulin treatments the US, death rate from rabies has dropped from 100 or more annually in the early 20th century, to 1-2 per year, mostly caused by bat bites, which may go unnoticed by the victim and hence untreated.

Related Topics:
Post-exposure prophylaxis - Immunoglobulin

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PEP is effective in treating rabies because the virus must travel from the site of infection through the peripheral nervous system (nerves in the body) before infecting the central nervous system (brain and spinal cord) and glands to cause lethal damage. This travel along the nerves is usually slow enough that vaccine and immunoglobulin can be administered to protect the brain and glands from infection. The amount of time this travel requires is dependent on how far the infected area is from the brain: if the victim is bitten in the face, for example, the time between initial infection and infection of the brain is very short and PEP may not be successful.

Related Topics:
Peripheral nervous system - Central nervous system

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