Hepatitis A virus
Epidemiology
- correlates with sanitation; very common in the majority world but pretty rare in Nova Scotia
- disease occurs on a sporadic, epidemic basis
Classification and Characteristics
- picornavirus
- single stranded, naked, iscosohedral
Transmission and Infection
- almost always fecal-oral, either directly or through food and water
- rare person-to-person or parenteral spread
- following ingestion, virus replicates in bowel and spreads through blood to liver
- icubation period of 15-49 days
- infective a few weeks before and a few weeks after symptoms
- virus is shed in stool till about 3 months following infection
Pathogenicity and Virulence
Clinical Manifesations
- most cases asymptomatic, especially during childhood
- adolescents or adults are symptomatic; most cases acute, not chronic hepatitis
- occasionally can turn progress to fulminant hepatitis
- no carrier state, no long term sequelae
Diagnosis
- acute infection confirmed by IgM antibodies, which decrease to zero by 6 months
- IgG levels remain high
Treatment
