The mysterious polio-like virus that is now affecting up to seven Washington families is also increasing nationwide.
U.S. health officials say at least 62 cases have been confirmed in 22 states this year. There are at least 65 additional illnesses in those states being investigated, according to the Centers for Disease Control and Prevention.
In Washington state, seven possible cases of acute flaccid myelitis (AFM) are being investigated in five counties, according to the Department of Health. Three are in King County, with Lewis, Pierce, Skagit, and Snohomish each seeing one case so far. None of the cases have been confirmed as AFM in Washington by the CDC.
Approximately 90 percent of cases are children who have experienced muscle weakness or paralysis. Symptoms tend to occur about a week after a fever or respirator illness.
The cause of AFM is unknown. Symptoms are similar to other viruses, which make it difficult to diagnose. Those symptoms include a drooping face and eyelids, trouble with eye movement, trouble swallowing, and slurred speech. Some people have had difficulty breathing.
Back in 2014 and 2016, the country saw similar waves of the illness. About 120 cases were confirmed in 2014, and 149 were reported in 2016.
The CDC recommends people follow normal disease prevention steps, including staying current on vaccines, washing hands, and avoiding mosquito bites.