The health unit considers AFP a disease of public health significance, and confirmed or suspected cases of the illness must be reported as soon as possible. Rare instances will result in acute flaccid myelitis, a serious condition that causes weakness in the arms or legs or even paralysis.
AFM impacts "the area of spinal cord called gray matter, which causes the muscles and reflexes in the body to become weak", the CDC says. Most of the cases involve children, and while the CDC says it doesn't know the cause of a lot of them, it is urging parents to practice disease-prevention steps, such as ensuring their children are up to date on vaccines, washing their hands, and protected from mosquito bites. One case involves an adult male and the other three cases involve children under the age of 18. "More children were ill with the flu past year than those who were diagnosed with AFM". According to its website, from August 2014 through September 2018 there have been a total of 386 confirmed cases of AFM in the United States.
Doctors and researchers don't know how or why AFM shows up in children or why cases occur in the late summer and fall.
The Centers for Disease Control and Prevention (CDC) has yet to determine a cause. "With AFM you don't get that recovery".
Parents should seek medical care right away if a child develops symptoms of AFM, which include sudden weakness and loss of muscle tone in the arms or legs.
"I think it is worrisome especially when we're not sure what's causing it", Dr. Bhargava says.
"What makes it worse is not knowing what caused it", said Erica Palacios, whose 2-year-old daughter, Abigail, began showing signs of AFM last month.
Shah says the best thing parents can do is to "continue being good parents". "Or if it's closer to the neck, they can't move head, neck and shoulders".
What are the treatments for AFM and the prognosis for a vaccine? "That's something that we're still really learning about", Jones said. And while some recover, others remain paralyzed.
Palacios says she wants answers to what causes AFM, and how to prevent and treat it - for Abigail, and for other families who have been affected by it.
Written by Michael Nedelman for CNN.