Cases of hepatitis A have increased sharply in three Maine counties since February.

The Maine Center for Disease Control and Prevention has recorded six cases in York County, seven in Somerset County and 13 in Penobscot County, all since March 1. There have been fewer than five cases in each of Maine’s 13 other counties since March 1, Maine CDC spokesman Robert Long said.

In all but five of the 26 cases, injection drug use or housing insecurity was a risk factor, according to the Maine CDC. The state had 45 cases of hepatitis A in 2019 after a decade in which a typical year had between seven and 10 cases.

The Maine CDC attributed last year’s increase to a restaurant-associated outbreak and cases related to injection drug use and housing insecurity. Investigations have not identified a source of the recent infections, it said.

Earlier this month, a restaurant worker in Saco tested positive for the disease.

Vaccines are the best way to prevent hepatitis A, a contagious liver disease caused by the hepatitis A virus. In the United States, the primary means of transmission is person to person, rather than through contaminated food or water.

Thirty-three states have reported outbreaks since 2016, mostly among drug users and homeless populations. New Hampshire, Vermont and Massachusetts are currently experiencing hepatitis A outbreaks. Nationally, more than 32,650 cases and 325 deaths related to hepatitis A have been reported since 2016.

The Maine CDC said anyone can benefit from vaccination against hepatitis A, but in particular, those who use drugs (and not only through injection), those experiencing homelessness, those currently or recently incarcerated and men who have sex with men.

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