Encephalitis B virus

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Encephalitis Bvirus
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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

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

• 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(?????)?aedes?anopheles
• Susceptible people
• The children under 10 years old is easy to be
  Infected
• Life time long immune to the virus

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The Piglet
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Characteristics of epidemiology

• EB only distributes in Asia.
• 8090 case all focus on July ,August, September.
• South china JuneJuly,
• north china JulyAugust,
  northeast August September,
• all identical to the density curve of
  mosquitoes.
• Highly disperse.

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Epidemic Region
Encephalitis B
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Clinical Manifestation

• Light type
• 3839?, always consciousness ??
• 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
• 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.

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

• IgM presents 57 days later after infection
• IgG hemagglutination inhibition antibody
• Neutralization antibody
• complement fixation antibody(no protection)
• Stable immunity,latent infection also can get the
  immunity

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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

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

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

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Prevention

• Kill mosquitoes

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• Inoculation of vaccine
• live attenuated vaccines
• Cell culture-derived inactivated vaccine
  (primary hamster kidney cell )
• children 6 months----10 years
• old in epidemic region.

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