OLYMPIA, Wash. (AP) – State officials have declared an outbreak of hepatitis A in people who are living without shelter or who use illicit drugs.

Washington state Department of Health officials said Tuesday they have confirmed 13 cases of the virus with ten cases in Spokane County, one in neighboring Pend Oreille County, two in Seattle’s King County and one in Snohomish County.

Officials say hepatitis A is a very contagious liver infection caused by the hepatitis A virus. It can range from mild with no symptoms to a severe illness lasting months that can result in liver failure and death.

Officials say the most effective way to prevent hepatitis A is vaccination. Officials are working with local health officials on prevention and response efforts.

People without access to restroom facilities and handwashing stations can be particularly at risk.