A child in the Cumberland and North Yarmouth school district has tested positive for the coronavirus, the superintendent announced Thursday.

Jeffrey Porter, superintendent of School Administrative District 51, said he was informed by the Maine Center for Disease Control and Prevention that a student at Mabel I. Wilson school has tested positive for the coronavirus.

The Maine CDC determined the transmission did not occur when school was in session based on the timeline of symptoms, Porter wrote in a letter to the school community. The student was exposed to the virus from a situation outside the school and the virus was not transmitted through the student to others, Porter said.

The school serves students in kindergarten through third grade. Officials did not disclose the age or grade level of the infected student.

Schools in MSAD 51 were last in session on March 13.

“I realize that any news of a positive case in our community, especially among school-aged students, is unsettling,” Porter wrote. “Please know that the importance of social distancing is more important than ever right now to slow down the spread of the coronavirus in our community and state.”

The Maine CDC said Wednesday there were 155 confirmed coronavirus cases statewide. Cumberland County remains the hot spot for coronavirus in Maine, accounting for 90 of the 155 cases statewide, according to a breakdown provided by the Maine CDC.