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Doctors should be on the lookout for a mysterious childhood illness that can cause muscle weakness and paralysis. That warning comes from the Centers for Disease Control and Prevention. The CDC, last year, documented the largest outbreak since it started tracking the illness in 2014. It found 233 cases in 41 states. NPR's Allison Aubrey has more.
ALLISON AUBREY, BYLINE: Kids who get this mystery disease called acute flaccid myelitis or AFM typically start off with what seems like a run-of-the-mill illness - a virus with a cough, fever. But then several days in, they may suddenly get neck pain and weakness. Nikita Shukla is a pediatric neurologist at Texas Children's Hospital. She saw her first cases of AFM last year.
NIKITA SHUKLA: So what I saw was weakness. They're not able to lift their arms or leg. And, usually, what I see is some respiratory difficulty at that time.
AUBREY: AFM is typically seen in very young children. The average age is 5 years old. Shukla says medicines such as steroids can help. And she says getting kids into physical therapy as soon as possible is also helpful. But unfortunately, more than 70% of kids who get AFM still have limb weakness months after they get sick. And Shukla says the disease is still very much of a mystery.
SHUKLA: I think the big question that needs to be answered is, what's causing this?
AUBREY: So far, it's not clear why some kids go from a mild virus to a condition that causes near paralysis within the span of a week. The CDC has stepped up its surveillance and research to try to figure it out. Here's the CDC's Anne Schuchat.
ANNE SCHUCHAT: Acute flaccid myelitis or AFM is a devastating illness for patients and their families.
AUBREY: Schuchat says the CDC does not know what's causing this disease, but important pieces of evidence point to viruses, which may trigger AFM. Among the kids who got AFM in 2018, about half were positive for either enterovirus or rhinovirus, which is a common cold virus. But she says there's still a lot to learn.
SCHUCHAT: We're working with local and state public health departments and collaborating with universities and the National Institutes of Health to conduct research.
AUBREY: Schuchat says one thing that can slow this down is when suspected cases are not reported promptly to local health departments, as was the case in 2018. So she says doctors should try to recognize symptoms early and take action.
SCHUCHAT: When specimens are collected as soon as possible, we have a better chance of understanding the causes of AFM and developing a diagnostic test.
AUBREY: Schuchat says peak season for the onset of the illness is just around the corner.
SCHUCHAT: Most patients develop AFM between August and October.
AUBREY: And she wants health care providers to be on the lookout.
Allison Aubrey, NPR News.
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