Background
Microbiology
- Non-enveloped RNA virus within the Picornavirus family
- Three genotypes, I through III
- Difficult to kill: needs higher temperatures and lower pH than other viruses, or bleach- or ammonium-based cleaners
Epidemiology
- Fecal-oral transmission with person-to-person spread (including sex)
- Can be transmitted by contaminated food and water, as well
- Most often linked to travel or to household contacts
Clinical Manifestations
- Incubation period is from 15 to 50 days, with an average of 28 days
Diagnosis
Serology
| IgM | IgG | Interpretation |
|---|---|---|
| – | – | No recent infection (unless in the incubation period). No prior infection or vaccination. |
| – | + | No infection. Prior infection or vaccination. |
| ? | + | Cannot rule out active infection. Prior infection or vaccination. |
| + | +/– | Acute or recent infection. IgM positive from 2 weeks until 3-12 months. IgG positive from 8-12 weeks and remains positive for lifetime. |
Prevention
Vaccination
- Vaccination is indicated for people at increased risk of acquiring hepatitis A, or at increased risk of severe disease
- Travellers to endemic countries
- People with chronic liver disease
- Men who have sex with men
- People who use recreational drugs
- People living in communities with outbreaks or endemic hepatitis A
- Close contacts of children adopted from endemic countires
- Military personnel and humanitarian relief workers
- People receiving repeated doses of plasma-derived clotting factors
- Laboratory workers studying hepatitis A
- Zookeepers, veterinarians, and researchers who interact with non-human primates
- Vaccination requires two doses spaced at least 6 months apart
- It provides immunity for decades, and possibly for life
- Often given combined with hepatitis B vaccine (HAHB)
- HAHB is given as three doses (for the hepatitis B component)
- The hepatitis A component contains a full dose of hepatitis A vaccine, so a HAHB series essentially contains an extra unnecessary dose of hepatitis A vaccine
- In people with contraindications or who are expected to have suboptimal response to vaccination, consider using immunoglobulin as preexposure prophylaxis
- Groups include:
- Infants less than 6 months of age
- Immunocompromised people in whom the vaccine may not be as effective (though they should also still be vaccinated)
- Anaphylaxis after previous hepatitis A vaccination or component thereof
- Adminitering just before travel can confer immunity for up to 6 months of travel
- Dose is IMIg (GamaSTAN) 0.02 mL/kg for 3 months of protection, or 0.06 mL/kg every 6 months
- CDC recommends a dose of IMIg (GamaSTAN S/D) 0.2 mL/kg q2mo due to decreases in hepatitis A IgG among donors
- Groups include:
Post-Exposure Prophylaxis
- Post-exposure prophylaxis is indicated for susceptible contacts including:
- Household members and close contacts of people infected with hepatitis A
- Contacts in group childcare centres and kindergartens
- Co-workers and clients of infected food handlers
- Prophylaxis is with monovalent hepatitis A vaccine
- In people with contraindications or who are expected to have suboptimal response to vaccination, immunogloulin should be given
- Groups include:
- Infants less than 6 months of age
- Immunocompromised people and people with liver disease, who should receive both vaccine and immunoglobulin
- If they have received IVIg ≥400 mg/kg within the 3 weeks before exposure, then they do not require further immunoglobulin
- Elderly susceptible adults age 60 years and older may also receive both
- It should be given as soon as possible, and can be given until 14 days after last exposure
- Dose is IMIg (GamaSTAN) 0.02 mL/kg body weight
- CDC recommends a dose of IMIg (GamaSTAN S/D) 0.1 mL/kg body weight due to decreases in hepatitis A IgG among donors
- Groups include:
