Epidemic Encephalitis B,Case report,History taking： A boy,4 years old，born in the countryside. Fever last for 4 days，convulsion and confusion last about 6 hours. Physical examination：T 40.5，R 30bpm，P 120bpm，BP100/60mmHg. Unconsciousness, conjunctival edema, lungs can be heard wheezes. Muscle hypertonia, knee hyperreflexia, Babinski sign(+) Other history? Accessory examination?,Abstract,Japanese encephalitis(JE), an acute infectious disease caused by the mosquito-borne Japanese encephalitis virus(JEV) and featured as inflammation in brain parenchyma. Fever, confusion, coma, convulsion,pathological reflex and meningeal irritation . Respiratory failure in severe cases,high mortality,and10% result in permanent neuropsychiatric sequelea.,Etiology,A single stranded RNA, 40-50nm,11 kilobases genomes.RNA genome is packaged in the capsid protein forming the core of the virus. The genomes also encodes several nonstructural proteins (NS1,NS2a,NS3,NS4a,NS4b,and NS5) JEV can be killed by disinfectant,100 2 minutes or 56 30 minutes,Etiology,Antigenic stability, infection can produce complement-binding antibodies, neutralizing antibodies and hemagglutination inhibition antibodies, contribute to clinical diagnosis and epidemiological investigation,Epidemiology,Sources of infection: JE is a zoonosis, mosquitoes become infected by feeding domestic pigs and wild birds infected with the JEV. JEV is amplified in the blood systems of the domestic pigs and wild birds. Pigs are the improtant amplified and reservoirs. Other reservior includes cow, sheep, horse,duck,goose and chicken.,Epidemiology,Route of transmission: the bite of an infected mosquito, primarily Culex species. Humans are a dead-end host in the JEV tramsmission cycle. JEV is not transmitted from person-to-person. Only domestic pigs and wild birds are carriers of the JEV.,Epidemiology,. Susceptible population: Generally susceptible, especially residents of rural areas in endemic location, mostly asymptomatic. The ratio of patients and latent infection was 1 :1000-2000 . Pre-existing antibodies. Countries that still have periodic epidemics include India ,Cambodia ,Nepal and so on.,Epidemiology,. Epidemic feature: most cases in temperate and subtropical areas occur from June to September, while in tropical areas occur throughout the year. Five genotypes : genotypes I ,II ,III, IV,V. Genotypes I and III occur principally in temperate, epidemic areas,and genotype II and IV occur principally in tropical ,endemic regions.,Pathogenesis and Pathology,JEV,Mononuclear macrophages multiply,viremia,Invade the CNS,Not invade the CNS,Incidence,Latent infection,This section of brain was taken from a patient with Japanese encephalitis, and shows the gross pathology found in all of the arbovirus encephalitides. The changes, which consist of perivascular congestion and hemorrhage, may be diffuse or focal, but they are seen predominantly in cortical gray and deep gray matter,Pathogenesis and Pathology,JEV,Direct invasion,Antigen-antibody binding to the immune attack,Nerve cell lesions,Vascular sheath formation,Thalamus, basal ganglia, brain stem, cerebellum,hippocampus, cerebral cortex,Glialcell proliferation,Show softening lesions, oval-shaped light pale area, the structure was loose mesh,Clinical manifestations,Incubation period of 5-15 days.the vast majority of infections are asymptomatic,only 1 in 250 infections develop into encephalitis. Typical manifestation:there are four stages The primary stage (1-3 days): onset was sudden with high fever, up to 39-41 in 1-2 days accompanied headache and malaise. Anorexia, nausea,or abdominal pain. Apathy and neck rigidity.,Clinical manifestations,The proximity stage (fourth to tenth days) Hyperthermia Conscious disturbance Convulsion Respiratory failure Other nervous symptoms and signs Circulation failure,Clinical manifestations,The proximity stage： Hyperthermia: acute onset; more than 40, lasts 7-10 days generally and some grave cases can last for 3 weeks. The higher temperature, the longer course, the more serious of JE.,Clinical manifestations,The proximity stage Conscious disturbance： Lethargy, delirium, coma, and disorientation are main presentations Appears mostly at the 3-8 days,lasting for almost 1 week A positive corralation between the serious and the lasting time of coma and the gravity of JE and prognosis,Clinical manifestations,The proximity stage Convulsion： Causes: high fever, cerebral edema, brain parenchymal inflammation One or more focal/asymmetric signs appearing in the first few days Light : the face, lips, local convulsions, severe cases of the body About 30% of survivors have frank persistent motor language impairment.,Clinical manifestations,Respiratory failure: caused by inflammatory of brain parenchyma, hypoxia, cerebral edema, acute intracranial hypertension and cerebral hernia Cerebral henia： Spitting vomiting, convulsions Coma increased Pupil changes. Anterior fontanel bulging, papilledema,Cli