Hepatitis C accounts for ∼ 20% of cases of acute hepatitis
Clinical Issues
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Symptoms generally mild or patients are asymptomatic
Fulminant hepatic failure is rare
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Most patients with acute hepatitis A virus infection fully recover within 2 months of disease onset
No specific drug therapy available for acute hepatitis A virus infection
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Laboratory values
Elevated transaminases at 5-10x normal values
Viral serologies often helpful
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Supportive care is mainstay of treatment for patients with acute hepatitis A or acute hepatitis E
Drug therapy (antivirals or immune modulators) may be useful in acute hepatitis B and C
Microscopic
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Lobular disarray characterized by diffuse lobular inflammation and hepatocyte swelling, necrosis, and regeneration
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May see mild portal and periportal inflammation, particularly in acute hepatitis A virus infection
TERMINOLOGY
Definitions
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Hepatocyte necrosis and inflammation resulting from acute viral infection
ETIOLOGY/PATHOGENESIS
Hepatitis A Virus
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Single-stranded RNA virus in Picornaviridae family
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Usually spreads via oral or fecal-oral transmission
Community outbreaks related to contaminated food or water
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Accounts for ∼ 1/2 of acute viral hepatitis cases in USA
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At least 4 genotypes described, but only 1 serotype exists
Infection with one genotype confers immunity against all genotypes
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Never results in chronic infection
Hepatitis B Virus
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Partially double-stranded DNA virus in Hepadnaviridae family
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Parenteral, perinatal, and sexual transmission
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Up to 40% of acute hepatitis cases in USA attributable to hepatitis B
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∼ 10% of infected patients develop chronic infection
Hepatitis C Virus
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RNA virus of Flaviviridae family
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Parenteral, perinatal, and sexual transmission
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Accounts for ∼ 20% of cases of acute hepatitis
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Only 10-15% of infected individuals develop symptomatic acute hepatitis
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If untreated, ∼ 85% of infected patients develop chronic infection
Hepatitis D Virus (Delta Agent)
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Parenteral and sexual transmission
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Requires coinfection with hepatitis B virus or superinfection in patient with chronic hepatitis B virus infection
Hepatitis E Virus
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Single-stranded, nonenveloped RNA virus in Caliciviridae family
Vertical transmission
Parenteral transmission
Consumption of raw or undercooked meat of infected animals
Contaminated water supply
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Endemic in parts of Asia, Africa, and India
CLINICAL ISSUES
Presentation
, single-cell necrosis 
, and areas of hepatocyte dropout 
in a background of lobular inflammation. The lobule looks disorganized at relatively low power, indicative of the injury to the hepatocytes.
, Kupffer cell hyperplasia 
, and lobular inflammation in a case of acute viral hepatitis.
, Kupffer cell hyperplasia 
, and lobular inflammation in a case of acute viral hepatitis.
