Acute flaccid myelitis, or AFM, is rare, but the Centers for Disease Control said it has become more common recently.
USA health officials on Tuesday reported a jump in cases of a rare paralyzing illness in children, and said it seems to be following an every-other-year pattern. Only one death has been reported, which involved an AFM illness reported in 2017.
It shows distinct abnormalities of the spinal cord gray matter on magnetic resonance imaging (MRI).
She said the CDC and research partners are casting a wide net trying to figure out what is causing the rise in cases, suggesting scientists have been looking at a variety of viruses and even environmental toxins in their search.
Standardized surveillance was established in 2015 to monitor this illness and attempt to estimate the baseline incidence.
Waves of similar illnesses occurred in 2014 and 2016. More than 90 percent of the confirmed cases have been in children 18 and under, with the average age being 4 years old.
Parents and clinicians should remember that this is a rare condition, affecting less than one in a million people, she said.
Since the condition was first recognized by CDC in 2014, the agency has confirmed 362 cases. "We actually don't know what is causing this increase".
Some patients recover quickly, while others experience paralysis and require ongoing care. The agency had a teleconference with health providers slated for later today, and it provided a toolkit for diagnosing AFM, along with instructions for reporting suspected cases.
Messonnier said the search for a cause is frustrating, and so far, no particular pathogen or immune response has been identified that would explain the big AFM peaks.
"As a parent myself I understand what it's like to be scared for your child", Messonnier said.
More broadly, she noted, "there is a lot we don't know about AFM".
In some individuals, health officials have determined that the condition was from infection with a type of virus that causes severe respiratory illness. Several cases have been linked to enteroviruses or other germs, but officials have not been able to find a cause for the majority of these cases. Officials will be conducting additional analysis on this year's cases.
20, the CDC had confirmed 38 cases in 16 states, which aren't required to report AFM cases to the CDC.
The CDC says disease prevention steps should be followed, including staying up to date on vaccines, washing hands and using mosquito repellant.
There is no specific treatment for AFM, but doctors may recommend physical or occupational therapy to help with arm or leg weakness. But some state health departments, such as Minnesota's, have reported the numbers.