What Is Acute Flaccid Myelitis? Why Researchers May Be Closer to a Vaccine

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Scientists have identified a likely culprit for the mysterious polio-like illness that has affected over 560 people, mostly children, since 2014. The disease is known as acute flaccid myelitis (AFM), and resembles polio by causing weakness in the arms and/or legs following an upper respiratory or stomach illness (fever, runny nose, cough, vomiting, and diarrhea). In some people, it can also result in difficulty moving the eyes or droopy eyelids, difficulty speaking or swallowing, or facial drooping. In the most severe cases, it can cause paralysis of the muscles that control breathing resulting in the need for mechanical ventilation. The progression of weakness is very fast, with many people reporting that it happens over a period of hours.  

Up until this point, the cause of the illness has remained largely unknown, but today, there’s good news from researchers at the Center for Infection and Immunity (CII) at Columbia University Mailman School of Public Health, the U.S. Centers for Disease Control and Prevention (CDC), and the University of California San Diego. They recently developed new techniques to help identify the elusive viruses likely responsible for causing this condition.  

What Causes AFM?

The prime suspect is a virus known as EV-D68, which is an enterovirus. Enteroviruses often infect the gut and are the same family of viruses responsible for polio. While the way AFM appears (and the fact that it occurs more in the summer months), led scientists to suspect AFM was caused by a virus that infected the spinal cord, but up until now they have had no evidence to support this theory. Researchers haven’t been able to isolate any virus from the spinal fluid of patients with the disease. So, for this experiment, scientists decided to take a different approach. Instead of trying to just find the virus, they developed a whole new technology to find footprints the virus may have left behind.

A New Vaccine?

The researchers studied the blood and spinal fluid of 14 people with AFM and five control patients without AFM. First, they used a very specialized technique called VirusCapSeq-VERT to try to find the viruses in spinal fluid (CSF). Using this technique, they found one enterovirus, known as EV-A71 in the one adult in their sample with AFM, but found no enteroviruses in the fluids of other AFM patients. 

Since they still couldn’t identify the virus using this advanced technology, they designed what they called the AFM-SeroChip-1 to look for evidence that a virus had been present. This technique looks for antibodies to enteroviruses in the CSF and blood of the study participants. Antibodies are very specific proteins made by our body to help our immune system fight off infections, so if a virus caused AFM, then a person with AFM, should have antibodies that are very specific to it. This special technique was necessary, because enteroviruses are not uncommon so many people have been exposed to them and have antibodies to them.The normal technique for identifying antibodies, would not be able to differentiate between these common antibodies and those unique to the specific virus (or viruses) causing AFM in an efficient way, but the new technique would.

They found antibodies to enteroviruses in 70 percent of the people studied (which remember is not surprising, since this family of viruses is not uncommon), but they did find antibodies to one very specific enterovirus, known as EV-D68 in only the patients with AFM. They found these antibodies in 43 percent of the CSF samples and 73 percent of the blood samples from AFM patients. So what does this all mean? This research strongly suggests that enteroviruses are likely responsible for AFM, with EV-D68 being a potential specific suspect. Still, more research needs to be done to know for sure, but these results may help us more quickly develop diagnostic tests and a vaccine in the future.  

Even though this is exciting news, it will take time before we can develop specific prevention measures, so the best thing to do now is still to recognize the symptoms and act quickly. If your child has the sudden onset of weakness anywhere in their body, consult your doctor and be sure to ask them if it could be AFM.   

Related:

What Is Polio?

Myth or Fact: 6 Things to Know About Vaccines

Everything You Need to Know About AFM