A microscopic image of the hepatitis A virus. Credit: Courtesy of the U.S. Food and Drug Administration

The number of reported cases of hepatitis A in Maine climbed by dozens last year, public health authorities said Thursday.

The Maine Center for Disease Control and Prevention said reported cases of the disease rose from nine in 2018 to 45 last year. A dozen of those cases were linked to a food-borne outbreak in Aroostook County in the northern part of the state.

The primary means of transmission of the virus in the U.S. is person-to-person, Maine health officials said. Thirty states in the U.S., including neighboring New Hampshire and Vermont, have reported outbreaks of hepatitis A. The Maine CDC said the outbreaks are primarily among people who use drugs or are experiencing homelessness.