Vaccinations:

Certain vaccinations can help prevent the diseases that can lead to encephalitis.

Measles

Measles used to be a very common childhood disease. In about 1 in 1,000 patients it can lead to encephalitis or death. The risk for these severe complications is highest in the very young and very old. Aggressive vaccination programs have reduced the incidence of measles in the U.S. to fewer than 100 cases a year. Rarely, patients who receive the live-measles vaccine develop encephalopathy (brain damage), but the risk is far lower than brain problems occuring from the disease itself.

Vaccine for Varicella Virus (Chickenpox and Shingles)

Herpes zoster, or shingles, is a reactivation of the varicella virus, which causes chickenpox. Children (and adults who do not have a history of infection and who lack evidence of immunity) should receive 2 doses of the chickenpox vaccine. In 2006, a vaccine for shingles became available for adults age 60 years and older. [For more information, see In-Depth Report #82: Shingles and Chickenpox.]

Vaccine against Flaviviruses (West Nile Virus, Japanese Encephalitis Virus, St. Louis Encephalitis)

Researchers are investigating a number of vaccines against the flavivirus family of arboviruses.

A vaccine (JE-VAX) is currently available for Japanese encephalitis. In travelers, it is only recommended for those visiting rural areas in high-risk Asian countries for more than 30 days. These countries include China, Korea, India and neighboring areas, and Southeast Asia. The disease may occur with lower frequency in Japan, Taiwan, Singapore, Hong Kong, and eastern Russia. A new type of Japanese encephalitis virus vaccine is currently in clinical trials.

Another type of vaccine (FSME-IMMUN) is used to prevent tick-borne encephalitis (TBE) in travelers visiting regions where this type of encephalitis is prevalent. TBE is found mainly in Eastern Europe, China, North Africa, and Russia. This vaccine is available in many European countries, but it is not yet approved in the United States.

Two types of vaccines, chimeric and DNA, are under investigation for West Nile virus, but it will be several years before these vaccines could become commercially available.

Rabies Vaccine and Immune Globulin

Anyone exposed to bats, or the secretions of an animal suspected of having rabies, should be evaluated for post-exposure rabies vaccine. Exposed individuals may also receive immune globulin unless they were previously vaccinated. Local health authorities are generally consulted. When the saliva of a potentially infected animal is exposed to an open wound or mucous membrane, treatment is generally warranted. However, the need to administer rabies immunization or immune globulin after saliva exposure to intact skin is not as clear. Veterinarians and animal handlers should be vaccinated. This does not eliminate the need for treatment if they are exposed to rabies, but it reduces the intensity of the treatment. Side effects of these shots include:

• Pain
• Redness
• Headache
• Stomach pain
• Nausea
• Dizziness
• Muscle aches
• Swelling at the injection site

Allergic response can occur after the first shot and as many as 21 days after a booster shot. Rare cases of neurological disorders have been reported that cause pain and paralysis in the legs and arms, which clear up in about 12 weeks.