questions 2

Microbiology of Hepatitis Viruses

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Topic updated on 11/18/15 12:26pm

Introduction
  • The hepatitis viruses primarily infect hepatocytes
  • Taxonomy
    • there are 4 important RNA hepatitis viruses
      • hepatitis A (HAV)
      • hepatitis C (HCV)
      • hepatitis D (HDV)
      • hepatitis E (HEV)
    • there is 1 important DNA hepatitis virus
      • hepatitis B (HBV)
  • Symptoms
    • patients infected with hepatitis suffer from
      • fever
      • jaundice
      • elevated ALT and AST
        • ALT > AST in viral hepatitis
        • AST > ALT in alcoholic hepatitis - "a Scotch and Tonic"
  • Chronic vs. acute disease
    • HBV and HCV can cause long-term chronic disease
      • chronic active hepatitis
      • cirrhosis
      • hepatocellular carcinoma
  • Transmission
    • HAV and HEV transmitted fecal-oral
      • "vowels from your bowels"
      • these viruses are naked and are not destroyed in the gut
Comparison chart
 
  HAV HBV HCV HDV HEV
Family Picornavirus Hepadnavirus Flavivirus Defective Hepevirus
Characteristics Naked RNA Enveloped DNA Enveloped RNA Enveloped RNA (circular) Naked RNA
Disease Mild acute
No chronic
Acute
Chronic (~20%)
Cirrhosis
Carcinoma

Acute
Chronic (70%)
Cirrhosis
Carcinoma

Co-infection or superinfection (worse) with HBV  Mild acute
No chronic
Transmission Fecal-oral Parenteral or sex Parenteral or sex Parenteral or sex Fecal-oral
Mortality <0.5% 1-2% 0.5-1% High 1-2% or 25% if pregnant 3rd trimester
Incubation period Short (3 wks) Long (3 mo) Short (6-12 wks) -- --
Carriers No Yes Yes Yes No
Vaccine available
Yes
Yes No (in clinical trials) No
No (in clinical trials)
Remember! A is Acute only B is Bad (many diseases, high mortality), Big like a "great dane" C is Chronic (leading cause for liver transplant) D is Dependent (needs HBV to infect -- HBsAg must coat HDAg)  E is Enteric in the far East (seen in Asia, not U.S.)


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