The U.S. has been polio-free for almost 40 years, but increasing reports of this mysterious polio-like illness, acute flaccid myelitis, are on the rise.
Beginning in August 2014, the Centers for Disease Control and Prevention (CDC) began receiving increased reports of people across the U.S., almost all children, who were ill with a rare and newly recognized polio-like illness, acute flaccid myelitis. For the first 10 months of 2016, a total of 50 people in 24 states were confirmed to have AFM. But as November rolled around, the CDC saw an unexpected surge in cases of the still mysterious malady — another 58 people, now in 36 states, have fallen ill with acute flaccid myelitis, or AFM.
While the cause of the disease remains currently unknown, acute flaccid myelitis symptoms bring back memories and concerns of the 20th century’s multiple polio epidemics that sickened tens of thousands of Americans, many of them children. Although it caused mild symptoms in some, other polio victims died or were left with varying degrees of paralysis (including the inability to breathe without an iron lung machine) after the virus invaded their brains and spinal cords.
The polio vaccine was introduced in l955 and soon cases of polio decreased. In fact, there has not been a single case of the disease in the U.S. since l979, according to the Centers for Disease Control and Prevention (CDC). However, over the past couple of years, newly recognized cases of the conditon have been on the increase, striking children and young adults, and causes symptoms much like those seen in polio, including paralysis.
AFM hits the nervous system, and MRIs show inflammation in nerve cells located in the spinal cord. Acute flaccid myelitis symptoms, including weak limbs and loss of muscle tone, typically develop and progress very suddenly, according to the CDC. Some patients have difficulty moving their eyes, swallowing and talking.
Carter Roberts, a three year old living in Chesterfield, Va., seemed to develop AFM literally overnight. He was a healthy, normal toddler until one evening he vomited. The next day, his mom, Robin, found he had a low grade fever and assumed the toddler had caught a cold. But 24 hours later, Carter couldn’t control his right arm, could hardly stand at all, and was crying, “Help me.”
He was hospitalized, and soon other muscles stopped moving normally. Carter was diagnosed with AFM and can now only wiggle a toe and move the left side of his face.
The CDC is following the increasing reports of the disease, but because this polio-type condition was unknown until two years ago, much remains to be learned about the illness. So far, the average age of youngsters who develop the condition is seven, although some patients have been older than 21. Almost all the affected kids have to be hospitalized and some, like many polio victims of the last century, need ventilators to help them breathe.
About 85 percent of children with AFM have improved — but only three youngsters have fully recovered. And15 percent of children stricken with the illness haven’t gotten better at all.
Obviously, the big question is what is causing this potentially serious condition? AFM symptoms are most similar to illnesses caused by viruses, although one specific virus hasn’t been pinpointed as the culprit.
Researchers from the University School of Medicine in Salt Lake City studied the cases of children, ages 13 months to 14 years, in the Western U.S. who developed AFM. Almost all had some virus-type symptoms before developing the condition. Seven had headaches, nausea, vomiting, or cough, and five had low grade fever about one to two days before suffering muscle weakness and paralysis.
A neuroimaging study by University of Colorado researchers of 11 youngsters with AFM revealed myelitis (inflammation of nerve cells in the spinal cord). Enteroviruses, including poliomyelitis (the enterovirus that causes polio), are known to cause similar inflammation. Although polio is now rare across the globe, numerous other human enteroviruses are common throughout the world and cause a variety of diseases, including respiratory infections and meningitis.
When the children studied by the University of Colorado research team became sick between August and September of 2014, there was widespread respiratory sickness in the U.S. caused by enterovirus D68. A well-known cause of respiratory illness, enterovirus D68 has, rarely, been linked to central nervous system symptoms like those of AFM.
While this might sound like enterovirus D68 was the “smoking gun” for the mysterious outbreak of polio-like acute flaccid myelitis, tests by the University of Colorado investigators found the virus in only four of the sick children tested. Four more ill youngsters tested positive for other enteroviruses or rhinoviruses (which cause the common cold). Tests for a host of other infectious agents, including West Nile virus and other arboviruses, herpes viruses, and poliovirus, were all negative in the kids suffering from AFM.
Currently, the specific causes of acute flaccid myelitis are under investigation, according to the CDC. However, some AFM cases have been associated with enteroviruses, West Nile virus. and associated viruses (Japanese encephalitis virus and Saint Louis encephalitis virus), cytomegalovirus, Epstein-Barr virus, and adenoviruses.
The CDC has decided to not identify the states with confirmed AFM cases, although individual states may release that information. It’s important to remember that, despite the increase in cases, AFM is still relatively rare.
However, parents and doctors need to be aware of the symptoms. The CDC advises contacting your doctor immediately if your child has problems walking or standing or develops sudden weakness in a leg or arm. Although there’s no specific treatment for the condition, a neurologist who specializes in treating brain and spinal cord illnesses can recommend specific interventions on a case-by-case basis.
For the latest information on AFM, visit the CDC’s acute flaccid myelitis home page.
February 27, 2020
Christopher Nystuen, MD, MBA