Today, federal health officials expressed worry about an uptick in acute flaccid myelitis (AFM), a mysterious and rare condition mostly affecting children. The CDC has been monitoring an increase in cases since 2014 and on Tuesday reported that it has confirmed 386 instances of AFM across the country over the last four years, majority involving children. A seventh case has been "clinically diagnosed", but remains under review by the CDC.
AFM may be caused by other viruses, including enterovirus, environmental toxins and a condition in which the body's immune system attacks and destroys tissue that it mistakes for foreign material, Messonnier said: "This is a mystery so far, and we haven't solved it yet, so we have to be thinking broadly". Fifteen states said they'd confirmed cases this year.
In some individuals, health officials have determined that the condition was from infection with a type of virus that causes severe respiratory illness. Most of the cases are in children under the age of 19, with kids under the age of 4 appearing to make up the biggest portion of cases.
The CDC received information on 33 confirmed cases of AFM across 16 states in 2017, 149 cases in 39 states.
Messonnier said the CDC has definitively ruled out polio - which causes a similar set of symptoms - as the cause. Symptoms include neck weakness or stiffness, drooping eyelids or a facial droop and difficulty swallowing or slurred speech. It affects the nervous system and can cause paralysis.
There were 120 cases in 2014 when the disease was first detected in the United States.
A general view of the Centers for Disease Control and Prevention (CDC) headquarters in Atlanta, Georgia September 30, 2014.More news: Google unshackles Android-device firms
About 90 percent of the cases have involved paralysis, according to the CDC.
"We know this can be frightening for parents", Messonnier said.
In addition to viruses, potential causes may include environmental toxins and genetic disorders, according to the CDC, and it "can be hard to diagnose because it shares numerous same symptoms as other neurologic diseases".
Rarely, people with AFM can suffer respiratory failure and require ventilator support when their breathing muscles become too weak. Another kind of virus was found in only some of the cases.
So far, the CDC has found no relationship between vaccines and children diagnosed with AFM from the 2014 cases.
Now 3 years old, Hunter has slowly recovered. But some states have previously announced clusters, including Minnesota, Illinois, Colorado, New York and Washington.