Encephalitis, Japanese

National Organization for Rare Disorders, Inc.

Skip to the navigation


It is possible that the main title of the report Encephalitis, Japanese is not the name you expected. Please check the synonyms listing to find the alternate name(s) and disorder subdivision(s) covered by this report.


  • Japanese B Encephalitis
  • JE
  • Russian Autumnal Encephalitis
  • Summer Encephalitis

Disorder Subdivisions

  • None

General Discussion

Japanese Encephalitis is a severe inflammation of the brain caused by the Japanese B Encephalitis Virus that is transmitted by the bite of infected mosquitoes in certain areas of the world, particularly Asia. This disorder most commonly affects children and tends to be more actively spread during the summer. Symptoms include high fever, headaches, weakness, nausea, vomiting, paralysis, personality changes, and coma, possibly leading to neurological damage or death.


Japanese Encephalitis is a rare viral disorder characterized by high fever, headaches, weakness, nausea, vomiting, mental deterioration, personality changes, psychoses, impaired speech, spastic rigidity, and paralysis of the face or extremities.

In adults, paralysis may occur on both sides of the body without altered sensation. The duration of symptoms can vary widely and convalescence may be prolonged. Some affected individuals may experience swelling and small areas of bleeding within the brain. Wasting away (atrophy) of brain and nerve cells may also occur. The immune system is also weakened by the virus, potentially making affected individuals vulnerable to more serious infections.


Japanese Encephalitis is caused by the Japanese B Encephalitis Virus, an arbovirus (mediated via insect bites), and transmitted through the bite of infected mosquitoes. Symptoms occur as the virus directly invades the central nervous system causing selective infection, destruction of nerve cells, and weakening of the immune system.

Affected Populations

Japanese Encephalitis occurs in approximately 20,000 people each year. The disorder erupts in the form of epidemics usually during the summer months in India, Bangladesh, the eastern part of Russia, China, Korea, Nepal, Burma, Viet Nam, and northern Thailand. In tropical areas of southeast Asia, southern India, southern Thailand, and Sri Lanka, the disease is present year-round and causes sporadic outbreaks. During the tropical rainy season, the illness can be transmitted in epidemic proportions.

Japanese Encephalitis is the leading cause of viral encephalitis in Asia, with approximately 30,000-50,000 cases being reported. Fewer than one case per year is reported among U.S. citizens and military personnel traveling to, or living in, Asia.

Standard Therapies

In Asian nations, vaccinations are available that prevent Japanese Encephalitis. American travelers to areas at risk can obtain the vaccination in the United States. High risk areas include India, Bangladesh, the eastern part of Russia, China, Korea, Nepal, Burma, Viet Nam, northern Thailand, tropical areas of southeast Asia, southern India, southern Thailand, and Sri Lanka.

Short-term travelers to Asian urban centers are at low risk to contract this disorder. The mosquitoes which transmit the virus appear in the greatest numbers in rural areas where standing water may be common and are most active at dawn, dusk, and on overcast days. Precautions against mosquito bites such as sleeping in screened quarters under mosquito netting, wearing clothing that adequately covers the skin, and using insect repellents on exposed skin are also advised. Repellents containing over thirty percent active ingredient N,N-diethyl-meta-toluamide ("deet") are recommended.

Investigational Therapies

Information on current clinical trials is posted on the Internet at www.clinicaltrials.gov. All studies receiving U.S. government funding, and some supported by private industry, are posted on this government web site.

For information about clinical trials being conducted at the NIH Clinical Center in Bethesda, MD, contact the NIH Patient Recruitment Office:

Tollfree: (800) 411-1222

TTY: (866) 411-1010

Email: prpl@cc.nih.gov

For information about clinical trials sponsored by private sources, contact:




Thoene JG., ed. Physicians' Guide to Rare Diseases. Montvale, NJ: Dowden Publishing Company Inc; 1995:545-46.

Fauci AS, et al., eds. Harrison's Principles of Internal Medicine, 14th Ed. New York, NY: McGraw-Hill, Inc; 1998:1138 .

Bennett JC, Plum F., eds. Cecil Textbook of Medicine. 20th ed. Philadelphia, PA: W.B. Saunders Co; 1996:1813-14.

Mandell GL, et al., eds. Mandell, Douglas and Bennett's Principles and Practice of Infectious Diseases. 4th ed. New York, NY: Churchill Livingstone Inc; 1995:1466-67.


Thompson, RF, et al., Travel vaccines. Infect Dis Clin North Am. 1999;13:149-67.

Sabchareon A, et al., Japanese encephalitis. Ann Trop Paediatr. 1998;18 Suppl:S67-71.

Abe T, et al., Japanes encephalitis. J Magn Reson Imaging. 1998;8:755-61.


Nakashima A, et al., A case of Japanese encephalitis: CT and MRI findings in acute and

convalescent stages. Radiat Med. 1999;17:369-71.

Cuzzubbo AJ, et al., Evaluation of a new commercially available immunoglobulin M capture enzyme-linked immunosorbent. J Clin Microbiol. 1999;37:3738-41.

Defraites RF, et al., Japanese encephalitis vaccine (inactivated, BIKEN) in U.S. soldiers: immunogenicity and safety of vaccine administered in two dosing regimens. Am J Trop Med Hyg. 1999;61:288-93.

Khang G, et al., Preparation and characterization of Japanese encephalitis virus vaccine loaded poly(L-lactide-co-glycide) microspheres for oral immunization. Biomed Mater Eng. 1999;9:49-59.

Robert-Thomson L, Japanese encephalitis. Aust Fam Physician. 1999;28:480.


Transverse Myelitis Association

1787 Sutter Parkway

Powell, OH 43065-8806


Tel: (614)766-1806

Email: info@myelitis.org

Internet: http://www.myelitis.org

Centers for Disease Control and Prevention

1600 Clifton Road NE

Atlanta, GA 30333

Tel: (404)639-3534

Tel: (800)232-4636

TDD: (888)232-6348

Email: cdcinfo@cdc.gov

Internet: http://www.cdc.gov/

NIH/National Institute of Allergy and Infectious Diseases

NIAID Office of Communications and Government Relations

5601 Fishers Lane, MSC 9806

Bethesda, MD 20892-9806

Tel: (301)496-5717

Fax: (301)402-3573

Tel: (866)284-4107

TDD: (800)877-8339

Email: ocpostoffice@niaid.nih.gov

Internet: http://www.niaid.nih.gov/

World Health Organization (WHO)

Avenue Appia 20

Geneva 27, 1211


Tel: 41227912111

Fax: 41227913111

Internet: http://www.who.int/en/

Encephalitis Global

18 North Broadway #404

Tarrytown, NY 10591


Tel: 604-980-2236

Fax: (604)904-0809

Email: admin@encephalitisglobal.org

Internet: http://www.encephalitisglobal.org

Encephalitis Society

32 Castlegate


North Yorkshire, YO17 7DT

United Kingdom

Tel: 4401653692583

Internet: http://www.encephalitis.info

Genetic and Rare Diseases (GARD) Information Center

PO Box 8126

Gaithersburg, MD 20898-8126

Tel: (301)251-4925

Fax: (301)251-4911

Tel: (888)205-2311

TDD: (888)205-3223

Internet: http://rarediseases.info.nih.gov/GARD/

For a Complete Report

This is an abstract of a report from the National Organization for Rare Disorders, Inc.® (NORD). Cigna members can access the complete report by logging into myCigna.com. For non-Cigna members, a copy of the complete report can be obtained for a small fee by visiting the NORD website. The complete report contains additional information including symptoms, causes, affected population, related disorders, standard and investigational treatments (if available), and references from medical literature. For a full-text version of this topic, see http://www.rarediseases.org/search/rdblist.html.