CLAYTON — A young woman who studied abroad in Italy before returning home to St. Louis County earlier this week is Missouri’s first positive case of the COVID-19 coronavirus, Gov. Mike Parson said Saturday night.

The 20-year-old woman had a fever and respiratory problems that prompted her to go to Mercy Hospital St. Louis in Creve Coeur. She was evaluated before returning home and quarantining herself along with her parents, who are not showing symptoms, health officials said at a news conference attended by Parson and County Executive Sam Page at county offices in Clayton.

Page said health officials are working to identify the people the woman came into contact with since her return from Italy. Officials declined to identify the woman or say where in the county she lives. She attends an out-of-state school, officials said.

“This is a serious challenge and our public health officials are up to the task,” Page said.

Parson said the woman’s test result is “presumptive positive,” and the result still needs to be confirmed by the federal Centers for Disease Control and Prevention. Page said it is “highly likely” the CDC will confirm it.