Health officials say a boy in Spokane County is the ninth person in Washington with a confirmed case of a rare syndrome that causes varying degrees of paralysis.

Multiple news outlets reported Tuesday that the boy under age 10 has acute flaccid myelitis, also known as AFM. The syndrome affects the spinal cord, resulting in arm or leg weakness or paralysis.

The other children found to have the syndrome this fall range in age from 3 to 14 and come from King, Pierce, Snohomish, Whatcom and Franklin counties.

The Seattle Times reports the Centers for Disease Control and Prevention is working with local health officials to investigate the uncommon cluster of cases in the state.

Scientists at the CDC are working to determine the exact cause of AFM.