AFM: Know the Symptoms of This Rare Paralyzing Virus

Acute flaccid myelitis (AFM) is extremely rare. Keep reminding yourself of that as you read this article.

AFM is a syndrome that can cause polio-like paralysis, especially in children. Most cases are caused by a virus called enterovirus D68 (EV-D68). Outbreaks have been seen in the U.S. in 2014, 2016 and 2018. However, only a small number of cases of AFM (fewer than 700 total) have been reported since the Centers for Disease Control and Prevention (CDC) started tracking cases in 2014.

Even though AFM is rare (nothing like the polio outbreaks in the 1940s and ’50s), it’s important to know the symptoms, because the outcome can be serious.

Doctors and researchers don’t know how many people have EV-D68 because in most people, including children, the symptoms are the same as the flu or common cold.

“Typically, it starts with fever and cold symptoms,” says UNC Health pediatric infectious diseases specialist Matthew Vogt, MD, PhD. “Then in a few days, when those symptoms start getting better, they start to feel weakness, usually in an arm, close to the shoulder, or a leg, close to the hip.”

When should you be concerned?

Parents don’t need to worry every time their child gets a cold, he says. If your child suddenly becomes weak in an arm or leg, however, get medical care right away. There are other symptoms to watch for, too, such as droopy eyelids and difficulty swallowing.

Once it starts, paralysis moves quickly, Dr. Vogt says. Within 24 to 72 hours, muscles throughout the body may become paralyzed, including the ones that help us breathe and swallow. People may need to be on a ventilator or feeding tube.

“The patient will need supportive care,” Dr. Vogt says. “Not every child progresses to the level of trouble breathing or swallowing, but we want to make sure that if they do, they are in a hospital, like UNC Children’s, with a pediatric intensive care unit. A patient should never die from acute flaccid myelitis if you stay on top of the symptoms.”

A patient will need intensive physical therapy, too, he says. “The sooner we start to reengage the muscles, the better chance there is for recovery,” he adds.

What happens to children who develop paralysis?

For some, the paralysis is permanent. Others recover completely. More likely, though, a person will recover partially but never completely regain full strength.

“They may not grow up to be a college athlete,” Dr. Vogt says, “but there is hope for getting off the ventilator or feeding tube, or for getting out of the wheelchair. Still, recovery is usually very slow.”

How does the virus spread?

Although AFM is extremely rare, its cause, EV-D68, seems to be relatively common and highly contagious, he says. Most of those affected are young children—around age 5 in the 2018 outbreak—but it also has been seen in teens and school-aged children.

“It spreads the same way rhinovirus (the common cold) spreads,” he says. “So, you should do all the same things you do to prevent getting a cold. Wash your hands before you eat. Cough or sneeze into a tissue or your sleeve, then wash your hands.”

The most important way to prevent the spread is to stay home if you are sick.

What is the treatment?

Currently, there is no treatment for the virus causing AFM, but Dr. Vogt and colleagues at UNC and other research universities and institutes are making progress developing antibodies that may limit the damage and help people recover sooner. Research into a vaccine or preventive therapy also is underway.

“The data are promising,” he says. “We’re highly optimistic.”

Is AFM the same as polio?

Yes and no. AFM is a syndrome, not a specific disease. A syndrome is a general term given to a group of symptoms that occur together.

Poliomyelitis is a specific infectious disease that can be prevented by a vaccine that is part of the routine vaccinations that children receive. Polio was declared eradicated in the U.S. in 1994, but in July 2022, an unvaccinated adult in New York state became paralyzed after contracting it.

“Years ago, poliomyelitis was the primary cause of acute flaccid myelitis,” Dr. Vogt says. “If someone came in today with polio, it would be labeled as AFM.”

According to the CDC, the symptoms of poliomyelitis usually are mild. One in four develop flu-like symptoms. Few develop paralysis (1 in 200 to 1 in 2,000, depending on the strain of virus). People who are unvaccinated for polio are at risk for becoming paralyzed if they become infected with poliomyelitis.

What should parents do?

Dr. Vogt advises parents to be vigilant about hand-washing and keeping kids home when they are sick. Be aware of the rare symptoms of AFM and get medical help immediately if a child shows muscle weakness.

“But remember,” he says, “usually a cold is just a cold.”

If you are concerned about your child’s symptoms, talk to their doctor, or find one near you.