An overall induction of differential expression of proinflammatory cytokines and chemokines from different brain regions during a progressive Japanese encephalitis infection was also observed.Although the net effect of the proinflammatory mediators is to kill infectious organisms and infected cells as well as to stimulate the production of molecules that amplify the mounting response to damage, it is also evident that in a nonregenerating organ such as the brain, a dysregulated innate immune response would be deleterious. In JE the tight regulation of microglial activation appears to be disturbed, resulting in an autotoxic loop of microglial activation that possibly leads to bystander neuronal damage. In animals, key signs include infertility and abortion in pigs, neurological disease in horses, and systemic signs including fever, lethargy and anorexia. Cause
It is a disease caused by the mosquito-borne Japanese encephalitis virus (JEV). Virology
JEV is a virus from the family Flaviviridae, part of the Japanese encephalitis serocomplex of 9 genetically and antigenically related viruses, some which are particularly severe in horses, and four known to infect humans including West Nile virus. The enveloped virus is closely related to the West Nile virus and the St. Louis encephalitis virus. The positive sense single-stranded RNA genome is packaged in the capsid which is formed by the capsid protein. The outer envelope is formed by envelope protein and is the protective antigen. It aids in entry of the virus into the cell. The genome also encodes several nonstructural proteins (NS1, NS2a, NS2b, NS3, N4a, NS4b, NS5). NS1 is produced as a secretory form also.
Japanese encephalitis (JE) is an infection of the brain caused by the Japanese encephalitis virus (JEV). While most infections result in little or no symptoms, occasional inflammation of the brain occurs. In these cases, symptoms may include headache, vomiting, fever, confusion and seizures. This occurs about 5 to 15 days after infection.JEV is generally spread by mosquitoes, specifically those of the Culex type. Pigs and wild birds serve as a reservoir for the virus. The disease occurs mostly outside of cities. Diagnosis is based on blood or cerebrospinal fluid testing.Prevention is generally with the Japanese encephalitis vaccine, which is both safe and effective. Other measures include avoiding mosquito bites. Once infected, there is no specific treatment, with care being supportive. This is generally carried out in a hospital. Permanent problems occur in up to half of people who recover from JE.The disease primarily occurs in East and Southeast Asia as well as the Western Pacific. About 3 billion people live in areas where the disease occurs. About 68,000 symptomatic cases occur a year, with about 17,000 deaths. Often, cases occur in outbreaks. The disease was first described in Japan in 1871. Signs and symptoms
The Japanese encephalitis virus (JEV) has an incubation period of 2 to 26 days. The vast majority of infections are asymptomatic: only 1 in 250 infections develop into encephalitis.Severe rigors may mark the onset of this disease in humans. Fever, headache and malaise are other non-specific symptoms of this disease which may last for a period of between 1 and 6 days.