Hepatitis A & E

Definition

Hepatitis A and E are viral infections causing acute inflammation of the liver, transmitted primarily via the fecal-oral route, often associated with poor sanitation and contaminated water or food.

Epidemiology

• Hepatitis A: global prevalence, endemic in developing countries; usually acquired in childhood
• Hepatitis E: endemic in Asia, Africa, Middle East; higher risk in pregnant women and immunocompromised
• Both affect all ages, but severity increases with age and comorbidities
• Hepatitis E genotype 1 and 2 cause outbreaks in resource-limited settings; genotype 3 and 4 are zoonotic
• Mortality is low in general population but higher in pregnant women with Hepatitis E (~10–25%)

Etiology

• Hepatitis A virus (HAV): Picornaviridae family, single-stranded RNA virus
• Hepatitis E virus (HEV): Hepeviridae family, single-stranded RNA virus
• Transmission: fecal-oral, contaminated water, food (shellfish, vegetables)
• Rarely via blood transfusion or vertical transmission (HEV)
• Risk factors: poor sanitation, travel to endemic areas, crowded living conditions

Pathophysiology

• Virus enters hepatocytes via bloodstream from intestine
• HAV: direct cytopathic effects limited, liver injury mainly immune-mediated
• HEV: hepatocyte infection triggers immune-mediated inflammation
• Replication within hepatocytes causes necrosis and cholestasis
• Acute inflammation leads to elevated liver enzymes, jaundice, and systemic symptoms
• Usually self-limiting, rarely progresses to fulminant hepatic failure