A mysterious illness that’s sickening and even paralyzing children is prompting warnings this week from federal health officials to seek medical care immediately should anyone develop its symptoms.
Acute flaccid myelitis (AFM), an extremely rare but serious condition that affects the nervous system and causes the body’s muscles and reflexes to become weak, is on the rise across the country, the Centers for Disease Control and Prevention said on Tuesday.
Despite that alarm, there are a lot of unknowns about the polio-like illness, including what causes it and why it affects more children ― at the average age of 4 ― than adults.
“More than 90 percent of the cases are in children age 18 years and younger,” Nancy Messonnier, the director of the National Center for Immunization and Respiratory Diseases, said at a CDC press conference.
“Despite extensive laboratory testing, we have not determined what pathogen or immune response caused the arm or leg weakness and paralysis in most patients,” she said.
Viruses, environmental toxins and genetic disorders are among the suspected causes of the illness, which often begins with fever, respiratory issues and muscle weakness.
“This is actually a pretty dramatic disease. These kids have a sudden onset of weakness,” said Messonnier.
Aaron Michael Milstone, an associate epidemiologist at Johns Hopkins Hospital in Baltimore and an associate professor of pediatrics, pointed out that the illness is more prominent in the fall during the respiratory and flu season, which could make it easier to go undetected initially.
“Just about every parent who has a young child, sometime in October or the winter, their child will have some cold or low-grade fever or something,” he told HuffPost.
“They’re presenting with weakness in some part of their body. It could be an arm, it could be a leg, it could be more,” he said of the patients’ symptoms. “Sometimes it stops there, sometimes it progresses. And as you would expect, it’s very scary for parents.”
To help prevent the illness’ spread, the CDC advises proper hand washing, staying up to date on vaccines and using mosquito repellent to avoid bites.
As of now, there is no vaccine or treatment for AFM.
“It means we’re stuck kind of waiting and watching to see how kids do and not being confident that we can really intervene at this point to improve their outcomes,” Milstone said.
The illness’ long-term effects are not known, and outcomes have been different for patients, with some recovering quickly and others having lasting paralysis and requiring ongoing care. There was one confirmed death last year, the CDC said on Tuesday.
Robin Roberts of Richmond, Virginia, spoke with NBC News about the death of her 5-year-old son, Carter, last month after he became paralyzed from his nose down because of the illness in 2016.
“I think I would tell parents to be vigilant in looking out for, you know, arms or legs not working, that floppy head, those respiratory symptoms that don’t seem consistent with other basic illnesses,” she said.
According to the CDC, the number of patients with AFM symptoms increases each year in August and September. So far this year, there have been 62 confirmed cases in 22 states.
The number of confirmed cases has been on the rise since late 2014, when there were 120 confirmed cases from August to December in 34 states.
The following year, there were 22 confirmed cases in 17 states, and 2016 saw 149 cases in 39 jurisdictions, including D.C. In 2017 there were 33 confirmed cases in 16 states. The U.S. has had 386 confirmed cases since August 2014.
“As a parent myself, I understand what it is like to be scared for your child. Parents need to know that AFM is very rare, even with the increase in cases that we are seeing now,” Messonnier said. “We recommend seeking medical care right away if you or your child develop sudden weakness of the arms or legs.”
Since AFM appears to intensify every other year, Milstone also expressed concern and hope that more will be done to prevent it from getting worse.
“As a parent, I’d say to the scientific community, what are we doing to prepare for 2020 so we don’t see another 100 kids affected by this?” he asked.
This story has been updated with comments from Aaron Michael Milstone.