Hepatitis A

Hepatitis A

The virus that does not cause chronic liver disease

Hepatitis A

“Infectious Hepatitis”First characterized in 1973Detected in human fecesHepatovirus genusA reportable infectious diseaseU.S. rate of infection 4/100,000Highest among children

Risk Factors

Sexual or household contact International travel Men who have sex w/ men (MSM) Intravenous drug abuse (IVDA) Daycare

Transmission

Unwitting contact w/ infected person Most cases unknown Primary route is fecal oral either by person to person contact or ingestion of contaminated food or water

Pathogenesis

After ingestion, the HAV survives gastric acid, moves to the small intestine and reaches the liver via the portal vein Replicates in hepatocyte cytoplasm Not a cytopathic virus Immune mediated cell damage more likely Once mature the HAV travels through sinusoids and enters bile canaliculi, released into the small intestine and systemic circulation, excreted in feces

Clinical Features

Incubation is usually 2 to 4 weeks, rarely 6 weeks Complete recovery within 2 months for > 50% Within 6 months for almost all others


Clinical Features
Low mortality in healthy people High mortality when older than age 60 High in presence of chronic liver disease High morbidity Around 20% need hospitalization Lost work days Most become jaundiced

Clinical Features

Asymptomatic < 2 year oldSymptomatic – 5 and older ill about 8 weeksCholestatic – jaundice lasts > 10 weeksRelapsing w/ 2 or more bouts acute HAV over a 6 to 10 week periodAcute liver failure – rare in young. When it occurs, is rapid i.e., within 4 weeks

Signs and Symptoms

Prodrome lasts 1-2 weeks: fatigue, asthenia, anorexia, nausea, vomiting, and abdominal pain Less common: fever, cephalgia, arthralgia, myalgia, and diarrhea Dark urine is followed by jaundice and hepatomegaly Less common: splenomegaly, cervical lymphadenopathy

Diagnosis

During acute infection, anti HAV IgM appears first HAV IgG antibody appears early in the course of infection and remains detectable for life, providing lifelong immunity

PreventionImmunization

All children 12 – 24 monthsTravelers, occupational exposure riskAll patients w/ hepatitis B or C or those awaiting liver transplantationHIV positive patientsMSMIVD users

Immunize

People w/ clotting factor deficiencies Lab workers handling live hepatitis A vaccine Need for post exposure prophylaxis uncommon. Administration of the vaccine is effective. If needed, administer immune serum globulin within 2 weeks 0.02 ml/Kg IM



Hepatitis A Vaccine
The vaccine is inactivated HAVSchedule for 2 – 18 years depends upon the manufacturer:Havirx: 720 EL U/.5mL @ 0, 6-12 moVaqta: 25 U.5mL @ 0, 6-18 mo

Hepatitis A Vaccine

For those over age 18: Havirx: 1440 EL U/1mL @ 0, 6-12 mo Vaqta: 50 U/1mL @ 0, 6-18 mo Adverse effects: rarely anaphylaxis, injection site induration, erythema, edema, fatigue, mild fever, malaise, anorexia, nausea Twinrix: 720 El U/1mL 0, 1, 6 mo plus 20 mcg HBV