Rabies vaccine
The rabies vaccine is a critical medical intervention designed to prevent rabies, a severe viral infection that affects the central nervous system and is transmitted through the saliva of infected animals, primarily through bites or scratches. The vaccine is composed of killed rabies virus and is administered as a series of shots following potential exposure to the virus. If administered promptly, it is highly effective in preventing the onset of symptoms, as rabies becomes untreatable once symptoms appear.
After exposure, individuals receive both rabies immunoglobulin (RIg) and a series of five rabies vaccine shots, which must be administered without delay. Pre-exposure vaccinations are available for those at high risk, such as veterinarians and wildlife handlers. Although side effects may occur, they are generally mild, including local swelling or systemic symptoms like headaches and nausea. The rabies vaccine is especially important, as rabies is always fatal without intervention; no cases have been reported among vaccinated individuals who were exposed to rabid animals. This underscores the vaccine's vital role in public health and animal control efforts in preventing rabies transmission.
Subject Terms
Rabies vaccine
Definition
Rabies vaccines are made from the killed rabies virus and are administered as a series of shots as soon as possible after a potential exposure. Rabies is a serious viral infection of the central nervous system. The virus is transmitted through the saliva of an infected animal through a bite or scratch. Licking alone rarely transmits the disease unless the infected saliva enters an open sore or a mucous membrane. All mammals, such as raccoons, skunks, ferrets, dogs, and cats, are susceptible to infection, but bats are the most commonly infected animals in the United States.
Although earlier administration of the rabies vaccine is preferred, it may be given at any time during the incubation phase. Once symptoms begin, however, it is too late for vaccination.
Disease Course
Rabies infection begins slowly with an incubation period of one to three months. The virus travels from the site of the bite through the nerves to the brain, where it replicates. The first symptoms are mild and vague, consisting of headaches, fatigue, and fever. The disease then progresses rapidly. Symptoms of advanced rabies infection include the characteristic hydrophobia, or fear of water, where the presence or even the thought of water causes muscle spasms in the throat. The infected person may become hyperactive and aggressive. As the disease progresses, the person becomes completely paralyzed and dies, often from respiratory failure.
Types
After exposure to rabies, the infected person will receive two types of vaccine. First, rabies immunoglobulin (RIg) is given at a dose based on the weight of the infected person. Part of the RIg is delivered at the site of the bite, if possible, and the remainder is injected into a muscle. The amount of RIg delivered to the wound depends on the size of the wound. Next, a series of five shots of either human-diploid-cell rabies vaccine (HDCV) or purified chick-embryo cell vaccine (PCEC) is administered intramuscularly immediately and then again at three, seven, fourteen, and twenty-eight days. All doses must be administered without interruption.
Pre-exposure vaccines are given to those at high risk for rabies exposure, such as veterinarians or anyone who frequently comes in contact with wild animals. These consist of either HDCV or PCEC, delivered intramuscularly for the initial dose then again at seven, fourteen, twenty-one, and twenty-eight days. After a rabies exposure, two doses of HDCV or PCEC are still required, but RIg is unnecessary.
The vaccines are recommended also for pregnant women who may have been exposed to the rabies virus. Infants and children receive the vaccines on the same schedule as adults, although the dose of RIg is proportionately smaller.
Side Effects
The most common vaccine side effects are swelling, redness, and itching at the vaccine site and headaches, nausea, abdominal pain, dizziness, or muscle aches in general. In rare cases, the person may develop hives or malaise.
Impact
Rabies cannot be treated, but it can be prevented with vaccination. The rabies vaccine is highly effective when administered as soon as possible after a possible exposure to the rabies virus. The disease is always fatal in unvaccinated people. No case of rabies has occurred in any person who has received the vaccine after exposure to animals proven to be rabid.
Bibliography
Atkinson, W., et al., eds. Epidemiology and Prevention of Vaccine-Preventable Diseases. 11th ed. Washington, D.C.: Public Health Foundation, 2009.
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Kienzle, Thomas E. Rabies. Philadelphia: Chelsea House, 2006.
Klosterman, Lorrie. Rabies. Tarrytown, N.Y.: Marshall Cavendish Benchmark, 2008.
Krauss, Hartmut, et al. Zoonoses: Infectious Diseases Transmissible from Animals to Humans. 3d ed. Washington, D.C.: ASM Press, 2003.
Pace, Brian, and Richard M. Glass. “Rabies.” Journal of the American Medical Association 284, no. 8 (August 30, 2000): 1052.
Parker, James N., and Philip M. Parker, eds. The Official Patient’s Sourcebook on Rabies. San Diego, Calif.: Icon Health, 2002.
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