DETROIT (AP) — Michigan has its second confirmed case this year of a mysterious paralyzing illness called acute flaccid myelitis.

The Michigan Department of Health and Human Services said Thursday it was notified by the Centers for Disease Control and Prevention that the state has a confirmed case in a child in Oakland County. An earlier case was included in adjacent Wayne County , which includes Detroit.

The state says nine suspected cases in Michigan are under investigation.

Officials have said this year's count nationally could surpass the tallies seen in similar outbreaks in 2014 and 2016 .

It's not clear what's causing some children to lose the ability to move their face, neck, back, arms or legs. Symptoms tend to occur about a week after the children had a fever and respiratory illness.