What is Japanese Encephalitis?

Japanese encephalitis is a viral disease spread by mosquito bites. The virus is transmitted by the mosquito after it feeds on pigs or wild birds. Like its name suggests, it is most often found in Japan and other Asian countries, usually in rural rice fields where mosquitoes are in higher numbers. While it is native to Japan, cases of the disease have been reported as far away as Russia, India, and Australia. Cases in America are extremely rare, although the occasional outbreak has occurred in U.S. territories in the Western Pacific. It is the leading cause of viral encephalitis in the world, with more than 50,000 cases reported each year. Japanese encephalitis can only be spread by mosquito bites.

Like all forms of viral encephalitis, the disease causes acute brain inflammation. Most cases are very mild and cause nothing more than a light fever and headache. When severe cases do occur, they can be life threatening. Symptoms of severe viral encephalitis include a high fever, stiffness in the neck and feelings of disorientation. Extremely severe cases can cause convulsions and loss of consciousness that can lead to a coma. Viral inflammation caused by the condition can lead to permanent brain damage in some cases and even death in the most severe instances. Because of the wide variance in symptoms, the mortality rate of the condition can change greatly from outbreak to outbreak. Estimates by the CDC (Center for Disease Control) place the mortality rate of Japanese encephalitis anywhere between 0.3 percent to 60 percent.

There is no specific treatment for any forms of viral encephalitis. Antibiotics are not effective against viral infections as a whole, and antiviral drugs are powerless against encephalitis. In cases of severe infection, the most that can be done for the patient is supportive therapy to alleviate his or her symptoms until the virus runs its course. There is preventative treatment however, including a vaccine. The vaccine for Japanese encephalitis must be administered in three stages over the course of 28 days, and boosters must be administered every three years to maintain its effectiveness. It is not commonly given to, but may be administered during widespread outbreaks in an attempt to stop further infections.

In many cases the simplest and most effective preventative measure that can be taken against Japanese encephalitis is to fight the mosquitoes that transmit it. Mosquito repellent can be used to help prevent the spread of any mosquito-born pathogen. Widespread preventive measures include keeping livestock pigs away from residential areas and spraying to kill large batches of mosquitoes before they can contract the virus and spread it to humans.