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Hepatitis A virus (HAV) infects the liver. It is primarily acquired via the fecal-oral route, either through person-to-person contact or by ingestion of fecally-contaminated food or water. Before routine childhood vaccination against hepatitis A, infection was common among children.

Today, adults account for the majority of cases. Most cases occur through consumption of contaminated food during travel. Hepatitis A has also been linked to sexual activity among men who have sex with men when oral contact with stool-contaminated skin occurs. Illicit drug users are also at higher risk of hepatitis A. Unlike hepatitis B or C, HAV does not cause chronic infection or carriage. HAV is more common in developing countries where sanitation is poor and vaccine is not available.

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Purpose of surveillance:

  • To identify persons exposed to cases of hepatitis A so that preventive treatment can be administered
  • To identify common source outbreaks
  • To identify and eliminate sources of transmission including contaminated food and water

Hepatitis A case data

Local epidemiology:

Nine cases of hepatitis A were reported in 2015 compared to a five-year average of 11 cases; three cases were hospitalized. Seven cases reported international travel to India (3), Mexico (3) and the Philippines (1). Risk factors could not be identified for two cases.

Prior to the introduction of hepatitis A vaccine in 1995, hundreds of cases occurred every year in King County, with cyclical peaks approximately every five years. Since the introduction of hepatitis A vaccine in 1995, cases have progressively declined locally and nationally.

Each year in Washington state between 20 and 45 cases of hepatitis A are reported.