NEW YORK — U.S. measles cases are continuing to jump, and most of the reported illnesses are in children.

Health officials say 465 measles cases have been reported this year, as of last week. That’s up from 387 the week before.

The numbers are preliminary. The 2019 tally is already the most since 2014, when 667 were reported. The most before that was 963 cases in 1994.

Outbreaks have hit several states, including California, Michigan and New Jersey. New York City accounted for about two-thirds of the U.S. cases reported last week.

The Maine Center for Disease Control and Prevention warned the public last week that a Massachusetts resident who had been diagnosed with measles visited two businesses in greater Portland last week, possibly exposing staff and customers to the virus.

Maine health officials said they were notified by the Massachusetts Department of Public Health that the individual – the person’s gender has not been disclosed – had a confirmed case of measles.

The infected person visited the Skin Clinic in Falmouth and the Maine Centers for Healthcare Endoscopy in Westbrook on March 27, the Maine CDC said in a news release. The visits occurred between 11 a.m. and 2 p.m., the CDC said.

Maine has one of the highest school vaccination opt-out rates in the nation. Parents are allowed to claim a philosophical or religious objection to vaccines when they enroll their children in school.

The last reported case of measles in Maine was 2017. That individual contracted the disease after traveling overseas.

After an infected person leaves a location, the virus remains alive for up to two hours on surfaces and in the air. The incubation period is typically 10 to 14 days, but can be as long as 21 days. Individuals who were exposed or begin to develop symptoms should  contact their health care provider.

Measles is so contagious that over 90 percent of people who are exposed and are not immune will get the disease.

The Maine CDC in its release said that measles can cause severe health complications that may include pneumonia, encephalitis and possibly death. Measles can be transmitted when an infected person coughs or sneezes. Infected people are contagious from four days before their rash starts to four days afterward.

The Centers for Disease Control and Prevention updated the numbers Monday. Roughly 80% of the cases are age 19 or younger.

The CDC recommends that all children get two doses of measles vaccine. It says the vaccine is 97% effective.