YAKIMA, Wash. (AP) – Yakima County has 18 confirmed cases of hepatitis A, a number authorities say will likely increase in the weeks and months ahead.

The Yakima Herald-Republic reports all cases are all tied to people experiencing homelessness and those using illicit drugs.

The Yakima Health District, in partnership with the Union Gospel Mission and Yakima Neighborhood Health Services, has vaccinated 129 people since the outbreak was reported in early November. Health officials also have been working with the Camp Hope homeless encampment and offering vaccines at clean needle exchanges.

Health officials expect the number of cases will continue to increase. Because the incubation period for hepatitis A is 15 to 50 days, someone can be infected and not know they are spreading it, said Melissa Sixberry, director of disease control for the health distric

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