What causes Japanese encephalitis?
Japanese encephalitis (JE) is a disease caused by a flavivirus that affects the membranes around the brain. Most JE virus infections are mild (fever and headache) or without apparent symptoms, but approximately 1 in 200 infections results in severe disease characterized by rapid onset of high fever, headache, neck stiffness, disorientation, coma, seizures,
spastic paralysis and death. The case fatality rate can be as high as 60% among those with disease symptoms; 30% of those who survive suffer from lasting damage to the central nervous system. In areas where the JE virus is common, encephalitis occurs mainly in young children because older children and adults have already been infected and are immune.
The virus causing Japanese encephalitis is transmitted by mosquitoes belonging to the Culex tritaeniorhynchus and Culex vishnui groups, which breed particularly in flooded rice fields. The virus circulates in ardeid birds (herons and egrets). Pigs are amplifying hosts, in that the virus reproduces in pigs and infects mosquitoes that take blood meals, but does not cause disease. The virus tends to spill over into human populations when infected mosquito populations build up explosively and the human biting rate increases (these culicines are normally zoophilic, i.e. they prefer to take blood meals from animals).
Japanese encephalitis is a leading cause of viral encephalitis in Asia with 30,000-50,000 clinical cases reported annually. It occurs from the islands of the Western Pacific in the east to the Pakistani border in the west, and from Korea in the north to Papua New Guinea in the south. Because of the critical role of pigs, its presence in Muslim countries is negligible. JE distribution is very significantly linked to irrigated rice production combined with pig rearing.
More information on encephalitis
What is encephalitis? - Encephalitis is an inflammation of the brain, caused by a direct viral infection or a hypersensitivity reaction to a virus or foreign protein.
What causes encephalitis? - The cause of encephalitis varies depending on the season, the area of the country, and the exposure of the child. Viruses are the leading cause of encephalitis.
What're the symptoms of encephalitis? - The symptoms of encephalitis vary depending on the cause of the encephalitis. Patients with encephalitis suffer from fever, headache, vomiting, confusion.
How is encephalitis diagnosed? - Diagnosis of encephalitis includes careful questioning to determine possible exposure to viral sources. Tests which can help confirm the diagnosis.
What's the treatment for encephalitis? - Choice of treatment for encephalitis will depend on the cause. Bacterial encephalitis is treated with antibiotics. Viral encephalitis is usually treated with antiviral drugs.
Can encephalitis be prevented? - Encephalitis may be prevented by avoiding the infection. Vaccines are available against some viruses, including polio, herpes B, Japanese encephalitis.
What is Japanese encephalitis? - Japanese encephalitis is a viral disease that infects animals and humans. Japanese encephalitis is a leading cause of viral encephalitis in Asia.
What causes Japanese encephalitis? - Japanese encephalitis (JE) is a disease caused by a flavivirus that affects the membranes around the brain.
What're the symptoms of Japanese encephalitis? - Japanese encephalitis begins with fever, severe headache, nausea, and vomiting. The patient will develop a stiff and painful neck.
How is Japanese encephalitis diagnosed? - The diagnosis of Japanese encephalitis is made primarily on the basis of the patient's symptoms and the knowledge of illnesses endemic to a particular geographic region.
What's the treatment for Japanese encephalitis? - There are no treatments available to stop or slow the progression of Japanese encephalitis. Only the symptoms of each patient can be treated.
What's herpes encephalitis? - Herpes encephalitis is inflammation of the brain. Herpes simplex infection is a relatively common cause of meningo-encephalitis.