CHARLESTON, W.Va. (AP) — A West Virginia hospital has confirmed the first known case of measles in the state since 2009, health officials said Monday.

The Monongalia County Health Department said WVU Medicine alerted officials Sunday that an adult patient living in the county tested positive for the viral infection. Health officials have not pinpointed exactly where and how the patient was exposed but said the person had recently traveled abroad.

The patient — who was partially vaccinated against measles, having received one of two doses — had developed symptoms, sought medical treatment through the WVU Medicine system and was instructed to stay home while awaiting lab results.

One of the world’s most contagious diseases, measles can lead to potentially serious complications.

Dr. Brian H. Huggins, the county health department’s incoming health officer, said the department is working with the hospital to identify people who came into contact with the patient.

“We really want to emphasize that this is an illness that people should take very seriously,” Huggins said.

Nationwide, measles cases this year already are nearly double the total for all of 2023, raising health experts’ concerns about the preventable, once-common childhood virus. Health officials have confirmed measles cases in at least 17 other states so far this year, including cases in New York City, Philadelphia and Chicago.

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The U.S. Centers for Disease Control and Prevention documented 113 cases as of April 5. There have been seven outbreaks and most U.S. cases — 73% — are linked to those flare-ups.

Still, the count is lower than some recent years: 2014 saw 667 cases and 2019 had 1,274.

Most U.S. cases are brought into the country by people who traveled where measles is far more common.

Huggins said West Virginia has not seen a case since 2009 largely due to its strict school vaccination laws. West Virginia is one of a handful of states that allows only medical exemptions to vaccine requirements.

Last month, Republican Gov. Jim Justice broke with West Virginia’s GOP-majority Legislature to veto a bill that would have allowed some students who don’t attend traditional public schools or don’t participate in sports and other group extracurricular activities to be exempt from vaccinations typically required for children.