Virus associated with polio-like muscle weakness is spreading among kids, CDC warns

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The Centers for Disease Control and Prevention is warning about the spread of a common childhood virus that can cause muscle weakness or paralysis in rare cases.

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CDC alert issued Friday about enterovirus D68, which usually leads to respiratory illness in children, with symptoms that are often mild but can be severe. The enterovirus family is large, and polio falls within it; Both EV-D68 and poliovirus can attack the nervous system and cause muscle weakness.

Occasionally, EV-D68 can result in a condition called acute flaccid myelitis, or AFM, which is characterized by inflammation in the neck region of the spine. Some people who experience AFM have difficulty moving their arms, while others experience weakness in all four extremities. During a major outbreak in the US in 2014, approximately EV-D68 . 10% of people with went on to develop AFM.


Full recovery from AFM is rare, and although most patients improve to some degree, the procedure is often difficult, and requires rehabilitation.

The CDC has identified more EV-D68 cases in children with severe respiratory disease this year than in the previous three years. There were 84 such cases from March to August 4. By comparison, the CDC identified six such cases in 2019, 30 in 2020 and 16 in 2021.

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However, those figures are likely to be low, as not everyone with respiratory symptoms is tested for EV-D68.

As of September 2, there have been 13 confirmed cases of AFM this year in the US. The CDC said it is investigating 20 additional cases.

In the past, the CDC has recorded spikes in EV-D68 cases every other year. Before the coronavirus pandemic, that was in 2014, 2016 and 2018. Dr. Benjamin Greenberg, a neurologist at UT Southwestern’s O’Donnell Brain Institute who treats patients at Children’s Health in Dallas, said the pattern is most visible as children develop immunity. When enteroviruses spread, there is a “off” year with high population immunity. Once the immunity is gone, the case numbers are ticked again.

Dr. Sarah Hopkins, a pediatrician at Children’s Hospital of Philadelphia, said: “We really thought it was going to happen in 2020, because we had the last spike in 2018. But then there was the wearing of masks and social distancing and all those things. With that limiting the spread of a respiratory virus, we didn’t have that expected spike.”

Greenberg said cases are likely to rise again this year as children are back in school and other public places.

“We now have a group of kids who have never seen the virus, because they didn’t have school exposures. So we think the at-risk population is larger than in 2020,” he said.

All seven pediatric centers affiliated with CDC’s New Vaccine Surveillance Network — in Nashville, Tennessee; Houston; Kansas City, Missouri; Cincinnati; Seattle; Pittsburgh; and Rochester, New York — have detected cases of EV-D68 this year. The CDC said it has received reports of an increase in serious respiratory illness in children in Minnesota, Arizona and Utah, raising concerns that some of those infections may also be EV-D68.

The agency is asking health care providers to be on the lookout for EV-D68 cases among children and to strongly consider AFM as a possible diagnosis for patients with limb weakness.

But distinguishing EV-D68 symptoms from those of the respiratory virus can be difficult, Greenberg said. Like the common cold, EV-D68 can cause runny nose, sneezing, body aches, or muscle aches. Children who require hospitalization develop cough, shortness of breath, wheezing, and fever in about half the cases.

AFM can also be confused with a severe case of polio, which results in a similar condition known as acute flaccid paralysis. The US reported one case of polio in July, and it has detected the virus in wastewater in several New York counties.

Greenberg said that the detection of polio “has been asked to raise awareness among health care providers so that they can send the appropriate tests.”

“It’s really important to know which virus is causing the paralysis in patients,” he said.

What is Enterovirus D68?

Greenberg said scientists first identified enterovirus D68 in 1962. At the time, the virus was not spreading much, and resulted in milder illness than today.

CDC started doing More Tests for EV-D68 In 2014, when scientists noticed a change in the behavior of the virus.

“The virus changed over time to acquire the ability to kill neurons without causing damage to the spinal cord,” Greenberg said.

This year’s total case is less as compared to 2018. From July to November of that year, there were 382 cases of EV-D68 in children with acute respiratory disease in the US.

“It doesn’t look like things have suddenly taken a dire turn for the worse,” said Dr. Keith Van Haren, an assistant neurology professor at Stanford University, “I hope at least there are no tidal waves of new neurological cases yet.” “

He said most EV-D68 cases happen between August and November at this time of the year.

If the past year is any indication, Greenberg said, “we will see a clear increase in the number of AFM cases over the next few weeks unless the virus has changed for the better.”

Van Haren said it takes one to four weeks for an EV-D68 case to reach AFM, although the situation can take different forms.

“The results range from slight shoulder weakness to difficulty moving all the extremities and sometimes even needing long-term respiratory support,” Hopkins said.

Van Haren said patients usually begin to recover from their respiratory symptoms before neurological symptoms appear.

“When neurological symptoms do start, they can start very suddenly. They can peak over the course of hours in a way that can be a little shocking,” he said.

Children who develop AFM usually need to be hospitalized. For reasons that scientists do not yet know, children at highest risk include children with a history of asthma.

There are no specific treatments for AFM. Doctors may provide antibody therapy to improve the patient’s immune response or provide supportive care such as ventilators or fluids.

The best way to protect yourself or your children from EV-D68, experts said, is to be diligent about washing hands and wearing a mask in public.

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