The main source of infection for epidemic B encephalitis is pigs. People infected with the encephalitis B virus may also experience transient viremia, which is a relatively small amount of virus in the body and lasts for a relatively short period of time, and is also a source of infection, but not a major source of infection. Epidemic B encephalitis is mainly transmitted through mosquito bites. Epidemic B encephalitis is mainly a contagious disease in the summer and autumn, mainly in children, adults are rare, the main performance of the brain parenchymal inflammation, will appear repeated high fever, impaired consciousness with convulsions and meningeal irritation and other characteristics. Some patients can be completely cured after treatment, while some patients may have some serious sequelae after treatment.