Hepatitis A virus: Difference between revisions

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== Background ==
 +
==Background==
−
=== Microbiology ===
 +
===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
  
   
  +
*Non-enveloped RNA virus within the [[Family::Picornaviridae]] family
−
=== Epidemiology ===
  
  +
*Three genotypes, I through III
−
* Fecal-oral transmission with person-to-person spread (including sex)
  
  +
*Difficult to kill: needs higher temperatures and lower pH than other viruses, or bleach- or ammonium-based cleaners
−
* Can be transmitted by contaminated food and water, as well
  
−
* Most often linked to travel or to household contacts
  
   
  +
===Epidemiology===
−
== Clinical Manifestations ==
  
  +
−
* Incubation period is from [[Usual incubation period::15 to 50 days]], with an average of 28 days
  
  +
*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
  +
*Rare transmission by blood transfusion
  +
  +
===Risk Factors===
  +
  +
*Outbreak
  +
*Close contact with a hepatitis A-infected person, including household, sexual, or other
  +
*Travel to endemic country
  +
*Men who have sex with men
  +
*Homelessness
  +
*Injection drug use
  +
  +
==Clinical Manifestations==
  +
  +
*Incubation period is from [[Usual incubation period::15 to 50 days]], with an average of 28 days
  +
*Children are usually asymptomatic
  +
*Symptoms include non-specific influenza-like illness followed eventually by bilirubinuria, pale stools, jaundice, and scleral icterus
  +
*May have hepatomegaly and splenomegaly, may have rash or arthralgia
  +
*Self-limited, usually starting to resolve by the third week of illness with full recovery often taking several months
  +
  +
==Diagnosis==
  +
===Serology===
  +
  +
* IgM and IgG antibodies are usually detectable by onset of symptoms
  +
* IgM becomes undetectable by about 6 months while IgG persist lifelong and are protective<ref>Jack T. Stapleton, Host Immune Response To Hepatitis A Virus, ''The Journal of Infectious Diseases'', Volume 171, Issue Supplement_1, March 1995, Pages S9–S14, https://doi.org/10.1093/infdis/171.Supplement_1.S9</ref>
   
−
== Diagnosis ==
  
−
=== Serology ===
  
 
{| class="wikitable"
  
{| class="wikitable"
−
! IgM !! IgG !! Interpretation
 +
!IgM!!IgG!!Interpretation
 
|-
  
|-
−
| – || – || No recent infection (unless in the incubation period). No prior infection or vaccination.
 +
|–||–||No recent infection (unless in the incubation period). No prior infection or vaccination.
 
|-
  
|-
−
| – || + || No infection. Prior infection or vaccination.
 +
|–||+||No infection. Prior infection or vaccination.
 
|-
  
|-
−
| ? || + || Cannot rule out active 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.
 +
| +||+/–||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==
−
[[Category:RNA viruses]]
  
  +
  +
===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 countries
  +
**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
  +
  +
==== Coformulation with Hepatitis B Vaccine ====
  +
  +
*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
  +
  +
==== High Risk Groups Who Cannot Receive 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
  +
*Administering 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
  +
  +
==== Publicly Funded in Ontario ====
  +
  +
* Only a subset of patients are publicly funded in Ontario:
  +
** Intravenous drug use
  +
** Chronic liver disease, including hepatitis B and C
  +
** Men who have sex with men
  +
  +
===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
  +
  +
[[Category:Picornaviridae]]
  +
[[Category:Gastrointestinal infections]]
  +
[[Category:Viral hepatitis]]

Revision as of 08:24, 11 October 2023

Background

Microbiology

  • Non-enveloped RNA virus within the Picornaviridae 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
  • Rare transmission by blood transfusion

Risk Factors

  • Outbreak
  • Close contact with a hepatitis A-infected person, including household, sexual, or other
  • Travel to endemic country
  • Men who have sex with men
  • Homelessness
  • Injection drug use

Clinical Manifestations

  • Incubation period is from 15 to 50 days, with an average of 28 days
  • Children are usually asymptomatic
  • Symptoms include non-specific influenza-like illness followed eventually by bilirubinuria, pale stools, jaundice, and scleral icterus
  • May have hepatomegaly and splenomegaly, may have rash or arthralgia
  • Self-limited, usually starting to resolve by the third week of illness with full recovery often taking several months

Diagnosis

Serology

  • IgM and IgG antibodies are usually detectable by onset of symptoms
  • IgM becomes undetectable by about 6 months while IgG persist lifelong and are protective[1]
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 countries
    • 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

Coformulation with Hepatitis B Vaccine

  • 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

High Risk Groups Who Cannot Receive 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
  • Administering 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

Publicly Funded in Ontario

  • Only a subset of patients are publicly funded in Ontario:
    • Intravenous drug use
    • Chronic liver disease, including hepatitis B and C
    • Men who have sex with men

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
  1. ↑ Jack T. Stapleton, Host Immune Response To Hepatitis A Virus, The Journal of Infectious Diseases, Volume 171, Issue Supplement_1, March 1995, Pages S9–S14, https://doi.org/10.1093/infdis/171.Supplement_1.S9

References

  1. ^  J. T. Stapleton. Host Immune Response To Hepatitis A Virus. Journal of Infectious Diseases. 1995;171(Supplement 1):S9-S14. doi:10.1093/infdis/171.supplement_1.s9.

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