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Public Health - Seattle & King County

Hepatitis A

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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Hepatitis A in King County

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:

Fourteen cases of hepatitis A were reported in 2013, eleven of which were in adults. Four cases were associated with travel to Asia (2 cases), Mexico (1 case) or South America (1 case). Two cases occurred in immigrants from Africa (1) and Asia (1). Three cases were hospitalized and one died. No King County cases were linked to the multistate outbreak associated with a frozen berry blend containing contaminated pomegranate seeds.

In 2011, a cluster of nine cases occurred among methamphetamine injection drug users and their contacts in East King County; one additional linked case lived in another county. The first case in the cluster was likely exposed while traveling to Mexico.

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.

In recent years, 20 to 60 cases have been reported annually in Washington state.