(CNN) The current measles outbreak in Washington state has tallied the highest number of infections since 1996, an official said Wednesday. The 37 cases there include 36 in Clark County, across the Columbia River from Portland, Oregon, and one case in King County, which includes Seattle; one case in Oregon is linked to the outbreak, Washington Secretary of Health John Wiesman said. Two patients have been hospitalized.

Hawaii also reported two cases of measles in travelers who were infected in Washington before their visit to the Big Island.

Measles is a contagious virus that spreads through the air via coughing and sneezing. One or two out of every 1,000 children who get measles will die from complications, according to the US Centers for Disease Control and Prevention.

The first case in this outbreak has been traced to an international traveler to Clark County who had contact with community groups with low vaccination rates, Wiesman said. Washington Department of Health officials identified 11 health care facilities, 13 schools and child-care centers and over 100 public places, including stores, where people may have been exposed to the virus, he said.

"We continue to have new cases occurring every week and almost by the day," Wiesman said. "We are fully expecting more counties to have cases, as well."

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