Encephalitis B virus

Biological properties Also called Japanese encephalitis virus (flavivirus ) +ssRNA Capsid: Icosahedral symmetry Enveloped Three kinds of structural proteins E the glycoprotein on the surface of envelope M inner surface of the envelope C the protein of the capsid Antigenicity stability

Picture of Encephalitis B virus

The course of infection the bite of an infected mosquito Proliferation in the endothelium of capillary and the regional lymph node Little into the blood caused the first viraemia Proliferation in the mono macrophage of the spleen and liver a secondary viraemia some cases the virus crosses the blood brain barrier Encephalitis Abortive infection

Epidemiology Source of infection and reservior host Source of infection and reservior host The major source is domestic animal 、 poultry pig→mosquito→pig Proliferation in mosquito and transmit to its eggs.The virus lives in the mosquito for ever. Vector Culex tritaeniorhynchus( 三带喙库蚊 ) 、 aedes 、 anopheles Susceptible people The children under 10 years old is easy to be Infected Life time long immune to the virus

The Piglet

Characteristics of epidemiology EB only distributes in Asia. 80 ～ 90% case all focus on July,August, September. South china June ～ July ， north china July ～ August, northeast August ～ September ， all identical to the density curve of mosquitoes. Highly disperse.

Epidemic Region Encephalitis B

Clinical Manifestation Light type 38 ～ 39 ℃, always consciousness 嗜睡 commonly no twitch,no evident stimulation to meninx,recovery within a week. Medium type 40 ℃ or so hard to conscious such as light coma,sometimes twitch,last 10days or so.  Severe type Severe type above 40 ℃， coma ， persistently twitch,may cause failure of respiratory,manifestation of different extent of mental disorder and paralysis during recovery.  Break-out type high fever ever super high fever, deep coma and repeated strongly twitch,may die due to centrally respiratory failure during very short time,even survivals often have severe sequelae.

coma above 40 ℃， coma ， persistently twitch,may cause failure of respiratory,manifestation of different extent of mental disorder and paralysis during recovery.

twitch paralysis

Immunity IgM presents 5~7 days later after infection IgG hemagglutination inhibition antibody Neutralization antibody complement fixation antibody （ no protection ） Stable immunity ， latent infection also can get the immunity

Microbiological detection Test for cerebrospinal fluid(CSF) PCR 100% specific Isolation and Identification Necropsy or viral culture using Vero, LLCMK2 and PS cells Serology test Source of false positive :heterologous flaviviral antibody

ELISA Test specific IgM Ab in serum or cerebrospinal fluid Hemagglutination inhibition test detect IgM antibodes and IgG antibodies Neutralizing test Early stage:IgM later stage:IgG Complement binding test

 Treatment No specific treatment Interferon-alpha A  Mortality less than 10% Report

Prevention Kill mosquitoes

Inoculation of vaccine live attenuated vaccines Cell culture-derived inactivated vaccine ( primary hamster kidney cell ) children 6 months years old in epidemic region.