All human cases of rabies were fatal until a vaccine was developed in 1885 by Louis Pasteur and Émile Roux. Their original vaccine was harvested from infected rabbits, from which the nerve tissue was weakened by allowing it to dry for five to ten days. Similar nerve tissue-derived vaccines are still used in some countries, as they are much cheaper than modern cell culture vaccines. The human diploid cell rabies vaccine was started in 1967; however, a new and less expensive purified chicken embryo cell vaccine and purified vero cell rabies vaccine are now available. A recombinant vaccine called V-RG has been successfully used in Belgium, France, Germany and the United States to prevent outbreaks of rabies in wildlife. Currently pre-exposure immunization has been used in both human and non-human populations, whereas in many jurisdictions domesticated animals are required to be vaccinated. In the U.S., since the widespread vaccination of domestic dogs and cats and the development of effective human vaccines and immunoglobulin treatments, the number of recorded deaths from rabies has dropped from one hundred or more annually in the early twentieth century, to 1–2 per year, mostly caused by bat bites, which may go unnoticed by the victim and hence untreated. September 28 is World Rabies Day, which promotes information on, and prevention and elimination of the disease.
There is no cure for rabies once symptoms of the disease develop, making prevention and control extremely important. Human deaths from rabies can effectively be prevented by vaccination. Rabies vaccine (pre-exposure vaccination) is given to people at high risk of being infected by rabies to protect them if they are exposed to the virus. The vaccine (post-exposure treatment) can also prevent the disease if it is given to a person after they have been exposed to the virus if treatment occurs fairly soon after exposure.
Pre-Exposure vaccination
Pre-Exposure rabies vaccination is usually recommended for those who do certain kinds of work or activities with a high risk of rabies exposure, such as:
- veterinarians
- lab workers who regularly handle rabies specimens
- hunters and trappers in high-risk areas
- animal control and wildlife workers
- spelunkers (cave explorers)
travellers in areas of high rabies activity where there is limited access to post-exposure treatment
Post-Exposure Treatment
Post-Exposure rabies treatment is given depending upon your risk of exposure to a rabid animal. Factors involved in determining this risk include the type of exposure and the type of animal involved. Your doctor or your local public health unit can help determine your risk of rabies exposure from animals in your area.
Soon after an exposure
Rabies vaccination should be obtained as soon as possible after an exposure. After you get any immunization, make sure your doctor updates your personal immunization record, such as your Yellow Immunization Card. Keep it in a safe place.
Vaccine Types
Four formulations of three inactivated rabies virus vaccines are licensed for use by the U.S. Food and Drug Administration (FDA). Two RIG formulations are also FDA-licensed.
HUMAN DIPLOID CELL VACCINE (HDCV).
Human diploid cell vaccines (HDCVs) use inactivated rabies viruses. HDCV comes in two formulations: one for intramuscular (IM) injection and one for intradermal (ID) injection into a deep layer of skin.
PURIFIED CHICK EMBRYO CELL VACCINE (PCEC).
Purified chick embryo cell (PCEC) vaccine became available in the United States in 1997. PCEC is made from rabies virus grown in cultures of chicken embryos and then inactivated. The drug is formulated for IM administration only.
RABIES VACCINE ADSORBED (RVA).
Rabies vaccine adsorbed (RVA) is manufactured from virus grown in cell cultures of fetal rhesus monkey lung cells and then inactivated.
RABIES IMMUNE GLOBULIN (RIG).
Human rabies immune globulin (RIG, HRIG) is a vaccine made from human serum that contains high levels of antibodies against rabies. It is used in conjunction with an inactivated-rabies vaccine for post-exposure prophylaxis. RIG provides immediate but short-lived protection against rabies. Approximately one-half of the antibodies are lost within 21 days after administration. RIG is separated from the blood plasma of hyperimmunized human donors. Numerous procedures are used to clear the serum of rabies virus.
OTHER VACCINES.
Although the four types of inactivated-rabies vaccines and the two RIGs are the only rabies vaccines available in the United States, various other rabies vaccines are produced throughout the world. Although inactivated-rabies vaccines from diploid cell cultures are safe and effective, they are expensive. In developing countries, rabies vaccines often contain nerve tissue which can cause adverse effects. Various less expensive but safe and effective vaccines are under development.
General Use
Inactivated-rabies vaccines are injected, either before or after exposure to the virus, in 1.0-ml. doses containing at least 2.5 IU/ml. of rabies virus antigen. This is the recommended standard of the World Health Organization (WHO). The size and number of vaccine doses are the same for children and adults. Although the same rabies vaccine usually is used throughout an immunization series, there is no evidence of adverse reactions or loss of effectiveness when two different vaccines are used in the same series. Modern rabies vaccines are relatively painless.
Side Effects
Side effects from the rabies vaccines currently used in the United States are much less common and less severe than the side effects of earlier rabies vaccines. However side effects may vary with the brand of vaccine and adverse reactions to rabies vaccines used in some other countries are quite common. The risk of side effects also increases with the number of vaccine doses. However a vaccination series should not be interrupted because of localized or mild side effects.
Mild side effects from rabies vaccines include:
soreness, redness, swelling, itching, or pain at the site of the injection in 30–74 percent of recipients
headache, nausea, abdominal pain, muscle aches, or dizziness in 5–40 percent of recipients
More serious side effects of rabies vaccines include:
hives, joint pain, or fever in about 6 percent of those receiving a booster vaccination
very rarely, an illness resembling Guillain-Barré syndrome, a disorder of the motor nerves that can result in temporary paralysis, lasting no longer than 12 weeks and resulting in complete recovery Other nervous system disorders occur so rarely following rabies vaccination that they may not be related to the vaccine. However, a physician should be consulted if a high fever or behavioral changes occur following rabies vaccination.
Reported side effects of RIG include:
- local pain
- low-grade fever
Although any vaccine is capable of inducing an allergic reaction, serious reactions to rabies vaccine are very rare. Signs of an allergic reaction include:
- paleness
- weakness
- dizziness
- hoarseness or wheezing
- difficulty breathing
- a fast heartbeat
In case of a serious reaction to a rabies vaccine:
Interactions
Immune system-suppressing treatments, including cancer drugs and radiation and steroids, can interfere with the antibody response to rabies vaccination. If possible, immunosuppressive medications should be suspended during the vaccination series, and the vaccine injections should be intramuscularly. Alternatively, the child's serum can be checked for antibody production to determine if the vaccination was successful.
Chloroquine phosphate or similar anti-malarial drugs such as mefloquine may interfere with the response to HDCV. Children who will be taking anti-malarial drugs while traveling in areas with endemic rabies should begin the three-dose regimen of ID vaccine one month prior to travel, before they begin taking drugs to prevent malaria. However, a three-dose, pre-exposure regimen of IM vaccine provides an adequate response even in the presence of anti-malarial drugs.
