B encephalitis virus is short for epidemic B encephalitis virus, with B encephalitis virus mosquito bite people after the B encephalitis virus will enter the human body. When the number of B encephalitis virus into the human body is not much, the toxicity is not strong, the infected body immunity is strong, the B encephalitis virus will be quickly cleared, will not cause serious consequences. When the number of viruses entering the body is large and virulent, and the immunity of the infected person is weak, the virus will invade the central nervous system and cause epidemic B encephalitis in the infected person. The encephalitis B virus can cause parenchymal brain lesions, so patients with epidemic encephalitis B often present with high fever, impaired consciousness, and in severe cases, may lead to general convulsions, respiratory failure, and even death.