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Date of preparation: March 2018

How contagious is hepatitis A?

Hepatitis A is transmitted when an uninfected (and not vaccinated) person ingests food or water that has been contaminated with the faeces of an infected person; an example is seafood such as shellfish. 1–3

This is because hepatitis A is closely associated with a lack of safe water, inadequate sanitation and poor personal hygiene. Water-borne outbreaks, though infrequent, are usually associated with sewage-contaminated or inadequately treated water. 12

The virus can also be transmitted through close physical contact with an infectious person, although casual contact among people does not spread the virus. 1

How long is the incubation period for hepatitis A?

The incubation period of hepatitis A is usually 14–28 days (but can be up to 50 days). 24

The virus begins replicating before any symptoms of the disease emerge, so individuals are infectious before they even know they have the virus. 5


  1. Fiore AE. Hepatitis A transmitted by food. Clin Infect Dis 2004;38:705-715.
  2. WHO. Hepatitis A Fact Sheet 328. 2014. Available at: Last accessed June 2015.
  3. Butt AA, Aldridge KE, Sanders CV. Infections related to the ingestion of seafood Part I: Viral and bacterial infections. Lancet Infect Dis 2004;4:201–212.
  4. WHO. WHO position paper on hepatitis A vaccines. Weekly Epidemiol Rec. 2012. Available at: Last accessed June 2015.
  5. WHO. Global Alert and Response. Hepatitis A. 2015. Available at: Last accessed June 2015

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