symptoms of acute flaccid myelitis

As late summer approaches, the U.S. Centers for Disease Control and Prevention is urging doctors to be on the lookout for a rare and mysterious  illness characterized by muscle weakness or paralysis in children.

The illness is called acute flaccid myelitis, or AFM, and according to the state  Department of Health, Pennsylvania had 11 confirmed cases last year and one confirmed and one suspected case this year.

Asked which counties the cases were in, a spokesman said that information was not available "because of the limited number of cases, and to protect patient privacy."

The CDC said there were 233 AFM cases across 41 states in 2018 — the largest outbreak so far, following 120 cases in 2014 and 149 in 2016. In all there have been 570 cases since 2014, spiking between August and October every other year.

The average age of patients was 5 years, according to the CDC, and the agency was notified of suspected cases an average of 18 days after patients' limb weakness began.

The CDC says the majority of patients were previously healthy and had respiratory symptoms or fever consistent with a viral infection less than a week before they experienced limb weakness.

The agency believes viruses, including enteroviruses, play a role in AFM, and says prompt reporting of possible cases is "critical to improve understanding of this complex syndrome, including its risk factors, outcomes, possible treatments, and ways to prevent it."

AFM has sometimes been described as "polio-like," but the agency said specimens it tested were negative for poliovirus. 

Currently, the agency said, "there are no proven ways to treat or prevent AFM."

"Many families say their children have regained at least some movement in affected limbs, but stories of complete recovery are unusual," an Associated Press story from April said. "Health officials cannot say how many recovered completely, partly or not at all, or how many have died, though the Centers for Disease Control and Prevention says deaths are rare."