HEPATITIS A VIRUS

Structure & Property	Transmission	Pathogenesis	Clinical findings	Laboratory diagnosis	Treatment	
Family: enterovirus within picornavirus

Genome: single strand RNA, +ve polarity.

Size: 27nm

Icosahedral nucleocapsid

Nonenveloped

Only one serotype

No antigenic relationship to HBV or other hepatitis viruses.	Affect mainly children 5-15 weeks.

Food-borne outbreaks affect adults.

Case-to-case spread: fecal-oral route, symptomless excretors are important source of infection.

Contaminated food or water by food-handlers excreting virus, pollution of water by infected sewerage (raw shellfish)

Blood transfusions.	Replicates in the gastrointestinal tract.

Spread to liver via blood.

Antibody appear at time of onset of jaundice.

Virus is excreted in faeces for 2 weeks before onset of jaundice, but for only up to 8 days after onset of symptoms.	Incubation period: 2-6 weeks

Most HAV infections are asymptomatic and detected solely by presence of IgG.

No chronic hepatitis or carrier state.	Diagnosis:
- detection of IgM antibody by ELISA.
- 4 fold rise in IgG antibody titer
	No antiviral therapy.

Hepatitis A virus:
- contains inactivated virus
- one dose injected intramuscularly, with optional booster 6-12 months later.
- one dose gives immunity for a year, two doses gives 10 years.

Passive immunization with serum globulin prior to infection or early in incubation period can prevent or mitigate disease.

Prevention: 
- observe proper hygiene
- proper sewerage disposal.