A Polio-Like Mystery Illness Is Afflicting U.S. Children Again This Year

October 8, 2018, 11:22 PM UTC

The Centers for Disease Control is expressing concern about an increase in confirmed cases of acute flaccid myelitis, or AFM, a neurologic condition that occurs mostly in children and can cause weakness in the arms and legs.

So far in 2018, the CDC has confirmed 38 cases of AFM in 16 states, with six cases reported in Minnesota. That’s down from 33 cases for all of 2017. The number of AFM cases seems to spike every other year, with 149 reported in 2016, 22 reported in 2015, and 120 in 2014. The median age of people with the condition is about seven years.

While fewer than 1 in a million people in the U.S. are diagnosed with AFM each year, the CDC is concerned about the recurrent outbreaks, especially given the mysterious nature of the illness.

AFM is believed to be caused by viruses, notably the enterovirus D68. Symptoms are similar to complications from other viruses such as the West Nile Virus or the poliovirus. Symptoms typically begin with a fever or cough, followed by sudden weakness in limbs, drooping of the eyes, slurred speech or difficulty swallowing.

The EV-D68 virus has seen occasional outbreaks, usually in the summer or autumn. It can often infect people with mild flu-like symptoms or no symptoms at all. Because the virus was present in many early confirmed cases of AFM, the CDC believes it to be a primary cause of the condition.

“It’s always important to practice disease prevention steps, such as staying up-to-date on vaccines, washing your hands, and protecting yourself from mosquito bites,” the CDC said on a page devoted to AFM. The agency is also studying AFM outbreaks to better understand the condition and uring healthcare providers to be vigilant about its symptoms.

A study of children diagnosed with AFM in Colorado in 2014 found that most of them were better one year later, although most also had residual weakness in their arms and legs.