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.
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. .
Symptoms of the following disorders can be similar to those of Japanese Encephalitis. Comparisons may be useful for a differential diagnosis:
Murray Valley Encephalitis is also known as Australian X Disease and is characterized by severe brain inflammation. The virus which causes this disorder is related to the Japanese B virus and is transmitted from mosquitoes to birds to other mosquitoes. Cases among children tend to be most severe. The first noticeable symptoms may be headache, fever, a general feeling of discomfort, drowsiness and/or convulsions, and a stiff neck. Extensive brain damage may result.
Saint Louis Encephalitis is characterized by less severe inflammation of the brain and the sheath surrounding the brain and spinal cord. Group B Arbovirus causes this type of Encephalitis in sporadic outbreaks in urban areas of Missouri, Arizona, Colorado, Nevada, Texas, Indiana, Illinois, Kentucky, Florida, New Jersey, Pennsylvania, and the Ohio Valley. This disorder tends to be more prevalent during midsummer to early fall. High fever, headache, nausea, vomiting, tiredness, dizziness, neck stiffness, irritability, confusion, and speech problems may occur.
West Nile Encephalitis is also known as West Nile Fever and is characterized by severe headaches, high fever, enlargement of the lymph nodes, and inflammation of the sheath surrounding the brain and spinal cord. Inflammation of the spinal cord may also occur. Symptoms of this disorder may last only a few weeks, but it may cause permanent neurological damage.
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.
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:
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Transverse Myelitis Association 1787 Sutter Parkway Powell, OH 43065-8806 USA Tel: (614)766-1806 Email: ssiegel@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)311-3435 Email: http://www.cdc.gov/netinfo.htm Internet: http://www.cdc.gov/
NIH/National Institute of Allergy and Infectious Diseases 6610 Rockledge Drive MSC 6612 Bethesda, MD 20892-6612 Tel: (301)496-5717 Fax: (301)402-3573 TDD: (800)877-8339 Internet: http://www.niaid.nih.gov/
World Health Organization (WHO) Regional Office for the Americas (AMRO) Pan American Health Organization (PAHO) 525 23rd Street NW Washington, DC 20037 Tel: (202)974-3000 Fax: (202)974-3663 Email: postmaster@paho.org Internet: http://www.who.ch/
Encephalitis Global 1638 Pierard Road North Vancouver British Columbia, Intl V7J 1Y2 Canada Tel: 604-980-2236 Fax: 6049040809 Email: admin@encephalitisglobal.org Internet: http://www.encephalitisglobal.org
Encephalitis Society 7B Saville Street Malton, North Yorkshire, YO17 7LL UK Tel: 44 (0) 1652 625 583 Email: mail@encephalitis.info Internet: http://www.encephalitis.info
Genetic and Rare Diseases (GARD) Information Center PO Box 8126 Gaithersburg, MD 20898-8126 Tel: (301)519-3194 Fax: (240)632-9164 Tel: (888)205-2311 TDD: (888)205-3223 Email: gardinfo@nih.gov Internet: http://www.genome.gov/10000409
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