Clark County Public Health Director Dr. Alan Melnick warned an audience at Washington State University Vancouver last week about the possible return of measles, following an outbreak earlier this year.

On Wednesday, public health officials confirmed one case of measles in an unvaccinated child, marking the return of measles in Clark County.

It came as no surprise to Melnick, who found out about the new case while attending a public health conference in Spokane on Wednesday.

“We still have a large number of people who are unvaccinated in Clark County,” Melnick said in a phone interview. “This will continue to happen.”

Measles is a highly contagious and potentially serious illness caused by a virus. It is spread through the air after a person with measles coughs or sneezes. A person with measles can spread the virus before they show symptoms. The virus also can linger in the air after someone who is infectious has left.