Hepatitis A Virus
Hepatitis A Virus
- Family: Picornaviridae
- Genus: Hepatovirus
- Originally called as enterovirus 72
Morphology
- Virion morphology and size:
- Nonenveloped
- icosahedral nucleocapsid symmetry
- spherical, 27-32 nm in diameter
- Nucleic acid:
- Linear, positive-sense, single-stranded RNA, ~7.5 kb in length
Common Human Exposure Routes:
- Fecal-oral route
Likelihood of Secondary Transmission:
- Moderate; from infected persons to close contacts
Cultivation:
- Only Hepatitis virus that can be cultivated in-vitro.
Resistant:
- Resistant to ether, acid and heat but sensitive to chlorination
Incubation Period:
- 2-4 weeks with a mode of ~1 month from exposure to symptoms regardless of the route of infection
Primary Disease Symptoms:
- Anicteric or icteric hepatitis
- MC cause of acute hepatitis in children.
- Prodrome of :
- anorexia
- spiky fever
- fatigue
- malaise
- vomiting
- The abrupt transition from well-being to acutely ill (within 24 h) in more that 60% of the cases
- Weight loss
- Disorder of taste and smell
- Right upper quadrant abdominal pain followed by an icteric phase within 10 days of the initial symptoms
Lab diagnosis of HAV
- Detection of IgM – specific anti-HAV in the blood of an acutely infected patient confirms the diagnosis of hepatitis A
- IgM appears in acute phase, peaking about 2 weeks after the elevation of liver enzymes and becomes undetectable within 3-6 months.
- ELISA is the method of choice for measuring antibodies.
Treatment
- Symptomatic no specific antiviral drug is given.
Hepatitis A (HepA) vaccines
- Routine vaccination
- Minimum age: 12 months
- Killed HepA vaccine(available in India):
- Start the 2-dose HepA vaccine series for children aged 12 through 23 months
- Separate the 2 doses by 6 months.
- Live attenuated H2-strain Hepatitis A vaccine:
- Single dose starting at 12 months and through 23 months of age
For Travellers:
- Normal human immunoglobulin:
- In a dose of 0.02-0.05 mg/kg of body weight
- Every 4 months.
Exam Question
- Hepatitis A spreads by feco-oral route.
- Incubation Period:
- 2-4 weeks with a mode of ~1 month from exposure to symptoms regardless of the route of infection
- Best test to diagnose prodrome of Hepatitis A is IgM anti-HAV.
- Vaccination
- Minimum age: 12 months
- Killed HepA vaccine(available in India): Start the 2-dose HepA vaccine series for children aged 12 through 23 months; separate the 2 doses by 6 months.
- Live attenuated H2-strain Hepatitis A vaccine: Single dose starting at 12 months and through 23 months of age
- For Travellers: Normal human immunoglobulin in a dose of 0.02-0.05 mg/kg of body weight.
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