A polio-like disease is on the rise across the U.S., health officials reported this week.

The rare condition has been documented in 24 states, with the majority of cases (90 percent) affecting children, according to the Center for Disease Control and Prevention (CDC), which has been monitoring cases of Acute Flaccid Myelitis (AFM) since 2014.

“It’s something that’s very scary for people because it’s a polio-like illness and it can show up in otherwise healthy children” Dr. Aaron Michael Milstone, the Associate Professor Pediatrics at John Hopkins University School of Medicine, tells PEOPLE.

AFM has a startling similarity to polio in its target of the nervous system and spinal chord and symptoms of limp weakness, paralysis and respiratory failure.

“We’ve been talking about this for a couple years now, we first noticed it two years ago,” says Milstone, who conducts research on AFM. “The speculation is that Enterovirus D68 is the cause of the virus.”

Some enteroviruses are very common and cause only mild illness. Ailments can range from common cold symptoms, but it can cause stronger effects in younger immune systems.

According to a report by the CDC, 120 AFM cases were reported across 34 states in 2014. The following year, 21 cases were reported and as of August 2016, 50 people in 24 states were confirmed to have this serious illness.

As for the severity of paralysis, doctors are unsure. In the cases from 2014, some children have completely recovered — but many did not.

Milstone advices concerned parents to implement general good health practices (washing hands frequently and avoiding contact with people who are sick) and to let common cold symptoms pass, but to be on alert for limb weakness.

“If they have weakness in the leg, the child may not walk right, they may limp a little or if they have trouble holding up their arms,” he explains. “That’s when they want to check in with their pediatrician.”

In addition to limb weakness and loss of muscle tone and reflexes, some patients may experience difficulty moving their eyes, drooping facial muscles and eyelids, difficulty swallowing and slurred speech, according to the CDC. Urination may also be difficult. The most severe symptom is respiratory failure if the muscles involved in breathing are weakened.

Since there isn’t an antiviral medicine for enterovirus D68 or for AFM, Milstone says they offer standard treatments.

“We treat kids supportively: give them Tylenol, try to keep them hydrated, that’s the standard of care we would give to anyone with one of these viral illnesses,” Milstone says. “Once they develop weakness, there are a number of things that people can try.”

Milstone is one of many doctors avidly researching the cause and treatment of AFM. And he says that he has seen cases where various families members have the virus but only one contracts AFM.

“We’re trying to find if there is a host genetic component that make people more likely to get this disease,” he says.

Despite increasing numbers of AFM, Milstone does not believe AFM is on the verge of an epidemic.

“I dont think this is an epidemic, but I wouldn’t be surprised if we see more cases over the next few months,” he says.