The U.S. Centers for Disease Control is warning about a rare mysterious illness affecting American children, which can cause “polio-like” symptoms.
In a press briefing Tuesday, officials talked about an increase in cases of acute flaccid myelitis (AFM) this year. So far in 2018, there have been 62 confirmed cases of the disease, an increase from last year. Since the CDC started keeping track in August 2014, there have been 386 cases of AFM – mostly in children. So far, 2016 was the worst year, with 149 confirmed cases.
“AFM is a rare, but serious condition that affects the nervous system. It specifically affects the area of spinal cord called gray matter and causes muscles and reflexes to become weak,” said Dr. Nancy Messonnier, director of the CDC’s National Center for Immunization and Respiratory Diseases.
In most cases, the patient’s arms or legs become weak, similar to the results of infection with polio. In some cases, patients recover quickly. In other cases, patients remain paralyzed. There was one death of a child who had AFM, in 2017, said Messonnier.
There is no specific treatment for AFM, according to the CDC, although neurologists might recommend things like physical therapy to help treat muscle weakness on a case-by-case basis. Experts don’t know the long-term effects of the disease.
In Canada, the disease is tracked as part of a larger category called “acute flaccid paralysis.” Between January and August 2018, there were fewer than five cases reported, according to the Public Health Agency of Canada, which they say is within the “normal range” of the disease. PHAC is monitoring CDC updates, however, “We haven’t found anything in Canada yet,” said Dr. Tim Booth, director of the viral diseases division of Canada’s National Microbiology Lab.
WATCH: Six children from Minnesota have been diagnosed with a rare condition that causes weakness or even paralysis in the arms and legs.
Despite its similarity to polio, none of the AFM patients has tested positive for the poliovirus, Messonnier said. The CDC actually doesn’t know what causes the disease or much about it at all.
“I am frustrated that despite all of our efforts we haven’t been able to identify the cause of this mystery illness,” she said.
“Despite extensive laboratory testing, we have not determined what pathogen or immune response caused the arm or leg weakness and paralysis in most patients. We don’t know who may be at higher risk for developing AFM or the reasons why they may be at higher risk. We don’t fully understand the long-term consequences of AFM.”
Although some AFM patients tested positive for an enterovirus, indicating a possible link, not all had the virus. The CDC says an outbreak in 2014 seemed to coincide with an outbreak of enterovirus D68, however the virus wasn’t found in every AFM patient.
Similar links have been found to West Nile virus, some environmental toxins and “a condition where the body’s immune system attacks and destroys body tissue that it mistakes for foreign material,” Messonnier said, and while these things are known to occasionally cause AFM, they haven’t found any cause for the majority of cases. To date, no pathogen has been consistently detected in AFM patients.
On a Facebook page dedicated to the disease, one parent posted that her daughter was diagnosed with AFM four years ago after catching enterovirus. Her daughter, now five, has regained the use of all her limbs except her right leg, though she still has weakness on her right side and uses a wheelchair or walker to get around.
At the press conference, Messonnier emphasized how rare the disease is.
“Overall, the rate of AFM over the years that it has been diagnosed which is since 2014 is less than one in a million.”
Although it’s rare, the CDC recommends seeking medical care right away if you or your child develop sudden weakness of the arms or legs.
“As we work to better understand what is causing AFM, parents can help protect their children from serious diseases by following prevention steps like washing their hands, staying up to date on recommended immunizations and using insect repellent,” Messonnier said.