Section 9 Epidemic encephalitis B

Introduction of Epidemic Encephalitis B

Epidemic encephalitis B is a natural focal acute infection caused by Japanese encephalitis virus（JEV）. Human beings，poultries，cattle and wild animals can acquire JEV and become the infection source. The disease is transmitted by mosquito bites. All populations are susceptible to JEV and immunity to JEV is enduring after a natural attack.

Encephalitis B is one the most widespread and severe insect-borne diseases predominantly infesting children younger than 10 years. The epidemic reaches a peak during June through September. In recent year morbidity of this disease keeps decreasing significantly.

Incubation period of Encephalitis B is 4-21 days. Most people infected with JEV develop dormant infection without any symptoms. Those mild only have ordinary respiratory or digestive symptoms or transient fever. Those typical manifest malaise，headache，fever and chili at the beginning，and 3-4 days later present continuing fever，conscious disorders，respiratory failure，intracranial hypertension and signs of meningeal irritation. Those severe may develop sequela including motion disorders，aphasia and mental disorders.

Infection confirmed by positive separation of JEV from brain tissues，cerebrospinal fluid or serum，positive test for specific IgG to JEV from specimens of cerebrospinal fluid or serum，a four-fold higher specific IgG titer to JEV during recovery period，or positive test for antibodies during the recovery period along with negative result during the acute period.

流行性乙型脑炎流行病学个案调查表

Epidemiological Questionnaire for Cases of Epidemic Encephalitis B

Questionnaire

（本节编者-陈宗遒　本节核对-刘方华　龙佳丽）