What is Japanese encephalitis?

Definition

Japanese encephalitis is a mosquito-borne virus that leads to swelling of the brain. It can affect the central nervous system and cause severe complications, even death.

Causes

Japanese encephalitis is caused by the bite of a mosquito infected with the virus.

Risk Factors

The factors that increase the chance of being exposed to Japanese encephalitis
include living or traveling in certain rural parts of Asia. According to the
Centers for
Disease Control and Prevention, outbreaks of Japanese
encephalitis have occurred in China, Korea, Japan, Taiwan, and Thailand. These
countries have controlled the disease through vaccinations. Other countries that
still have periodic epidemics include Vietnam, Cambodia,
Myanmar, India, Nepal, and Malaysia. Also, laboratory workers who might be exposed
to the virus are at high risk for developing Japanese encephalitis.

Symptoms

Symptoms of Japanese encephalitis, which usually appear five to fifteen days after the bite of an infected mosquito, include agitation, brain damage, chills, coma, confusion, convulsions (especially in infants), fever, headache, nausea, neck stiffness, paralysis, tiredness, tremors, and vomiting.

Screening and Diagnosis

A doctor will ask about symptoms and medical history and will perform a
physical exam. Tests may include blood tests to look for antibodies, a
magnetic
resonance imaging (MRI) scan (a scan that uses radio waves
and a powerful magnet to produce detailed computer images), a computed tomography (CT)
scan (a detailed X-ray picture that identifies abnormalities
of fine tissue structure), and cerebrospinal fluid tests.

Treatment and Therapy

Because there is no specific treatment for Japanese encephalitis, care is concentrated on treating specific symptoms and complications.

Prevention and Outcomes

A Japanese encephalitis vaccine is recommended for people who live or travel in certain rural parts of Asia and for laboratory workers who are at risk of exposure to the virus. Also, to protect against mosquito bites and to prevent the disease, one should remain in well-screened areas, wear clothes that cover most of the body, and use on skin and clothing those insect repellents that contain up to 30 percent NN-diethyl metatoluamide (DEET).

Bibliography

Booss, John, Margaret Esiri, and Margaret M. Esin, eds. Viral Encephalitis in Humans. Washington, D.C.: ASM Press, 2003.

Centers for Disease Control and Prevention. “Japanese Encephalitis.” Available at http://www.cdc.gov.

EBSCO Publishing. DynaMed: Japanese Encephalitis. Available through http://www.ebscohost.com/dynamed.

Goddard, Jerome. Physician’s Guide to Arthropods of Medical Importance. 4th ed. Boca Raton, Fla.: CRC Press, 2003.

Marquardt, William C., ed. Biology of Disease Vectors. 2d ed. New York: Academic Press/Elsevier, 2005.

National Institute of Neurological Disorders and Stroke. “Meningitis and Encephalitis Fact Sheet.” Available at http://www.ninds.nih.gov.

Peters, C. J. “Infections Caused by Arthropod- and Rodent-Borne Viruses.” In Harrison’s Principles of Internal Medicine, edited by Anthony Fauci et al. 17th ed. New York: McGraw-Hill, 2008.

United Nations International Children’s Emergency Fund. “Vaccine Is Key to Preventing Outbreaks of Japanese Encephalitis.” Available at http://www.unicef.org/infobycountry/india_28555.html.