In 2014, the CDC (Centers for Disease Control and Prevention) noticed a surprising number of polio-like illnesses in children. Most of these children were otherwise healthy individuals who suddenly developed weakness or paralysis of the arms of legs. Some have since recovered; others continue to struggle with weakness and limited mobility. Since 2014, the CDC has confirmed more than 520 U.S. cases of acute flaccid myelitis (AFM), the official name for this rare medical condition. The number of cases seems to spike every two years: In 2014, there were at least 120 confirmed cases; in 2015, 22 cases. In 2016, there were 149 confirmed cases, compared to 35 cases in 2017. There were at least 200 confirmed cases of AFM in 2018. What’s the risk of developing acute flaccid myelitis? Despite the recent uptick in cases, AFM remains rare. According to the CDC, less than 1 to 2 people in a million American children will develop AFM in a year. Most children who are diagnosed are between ages 4 and 8. In almost every case, the affected person had either a fever or respiratory illness—such as a cold—a few days before developing sudden weakness or paralysis. People with AFM disease may also have difficulty swallowing or moving their eyes or exhibit slurred speech. If you notice any of these symptoms, seek medical attention right away. AFM is dangerous because it can weaken the muscles necessary to breathe—a potentially life-threatening complication that requires immediate medical intervention. No one knows exactly what causes AFM. Because most people who develop AFM had a fever or cold-like symptoms before developing AFM symptoms, scientists suspect a virus may cause the disease. Researchers have found viruses, including coxsackieviruses and other enteroviruses, in the spinal fluid of a few people with AFM. But millions of people every year who are exposed to enteroviruses do not develop AFM. Scientists at the CDC and elsewhere are trying to understand what triggers this disease. As of yet, there is no single AFM virus shown to cause the condition. At present, researchers and healthcare providers don’t believe AFM is contagious in the same way that strep throat and the common cold are. That’s because AFM doesn’t seem to spread through families. Typically, only one person is affected in a family. Scientists are still searching for effective treatments. Because researchers aren’t sure exactly how AFM develops, they haven’t been able to design targeted treatments. Right now, medical care is supportive, which means that healthcare providers use medications and treatments to keep patients’ bodies functioning and comfortable. According to the CDC, there are no particular advised or ill-advised medical treatments for AFM. Healthcare providers have tried a lot of different treatments, including antiviral medication, steroids, immunoglobulin therapy, and plasma exchange, but there’s no clear evidence any of these treatments improve symptoms or prognosis. Physical therapy is essential for people with AFM and should be started as soon as possible. Regular physical therapy may help patients regain strength and function. Some surgeons have helped children regain function by performing nerve transfer surgery. Such surgery is still rare and not available everywhere. Surgeons who have performed such surgeries say they have the best chance of success when surgery is performed within 8 to 12 months of initial symptoms. The CDC has established an AFM taskforce dedicated to learning more about this condition. As scientists learn more about the causes and spread of AFM, clinicians continue to experiment with treatments. Hopefully, this research will soon lead to effective AFM treatment and prevention strategies.