What type of virus is hepatitis A?
Non-enveloped icosahedreal RNA virus from the Picornaviridae family.
What is the primary transmission route of hepatitis A virus (HAV)?
Fecal-oral transmission through contaminated food, water, or close contact.
What foods are classically associated with HAV outbreaks?
Contaminated shellfish, strawberries, and onions.
What is the incubation period of hepatitis A infection?
2–6 weeks.
Where is HAV endemic?
Tropical and subtropical regions, underdeloped and poor hygenic conditions
What populations most commonly acquire hepatitis A in endemic regions?
Children in developing countries, often infected before age 10.
Does hepatitis A cause chronic infection?
No, hepatitis A causes an acute self-limited infection.
What causes hepatocyte injury in hepatitis A infection?
Immune-mediated cytotoxicity by host immune cells, not direct viral cytopathic effect
Phases of HAV
Preicteric and icteric
Gold standard for HAV diagnosis
IgM anti-HAV (positive for acute disease)
What are the characteristic histologic findings in hepatitis A infection?
Periportal mononuclear infiltrates, lobular necrosis, hepatocyte ballooning, and apoptosis
Other diagnosis for HAV
IgG anti-HAV → indicates past infection or immunity, not active disease.I
Elevated ALT and AST, often >500–1000 U/L in acute viral hepatitis.
Complications of HAV
Fulminant hepatitis
Relapsing hepatitis
Persistent cholestasis
Immune mediated extrahepatic complications
Signs and symptoms of HAV
*might go unnoticed
What unusual clinical patterns can occur in hepatitis A?
Relapsing hepatitis and prolonged cholestatic phase.
What is the approximate case fatality rate of hepatitis A infection?
0.3–0.8%, higher in adults >60 years.
What is the efficacy of the hepatitis A vaccine?
94–100% protection after two doses.
What is PEP (post expousre prophylaxixs)?
Treatment given after someone has been exposed to an infectious agent to prevent disease from devoloping.
What is used for HAV post-exposure prophylaxis?
Immune globulin within 10–14 days of exposure.
Why does immune globulin work for PEP for HAV?
Contains prefromed IgG antibodies against HAV collected from donors, and the antibodies neutralizes the virus before it infects the hepatocytes (passives imunity)
