Upsurge of Mysterious Polio-Like Cases in Some US States: CDC

Acute Flaccid Myelitis can cause sudden weakness and paralysis
October 30, 2018 Updated: November 29, 2018

There has been a recent upsurge in cases of a rare Polio-like illness across the United States, which affects mainly children, according to the Centers for Disease Control and Prevention (CDC). The mysterious condition, known as Acute Flaccid Myelitis (AFM) can cause a sudden weakness in the limbs and potentially paralysis.

There have been a “substantially larger number” of suspected AFM cases reported in August, September, and October compared to previous months in 2018, the CDC website warns.

In 2018 so far, there have been a total of 191 reports of suspected cases across the country. Of these, 72 cases across 24 states have been confirmed.

The CDC says the condition remains rare—less than one in a million people in the United States get it each year. The cause of most AFM cases is not known.

Dr. Nancy Messonnier, who directs the CDC’s National Center for Immunization and Respiratory Diseases, described AFM as a “pretty dramatic disease.”

“AFM is a very rare condition. It is also a serious condition. We want to encourage parents to seek medical care right away if you or your child develops symptoms of AFM, such as sudden weakness and loss of muscle tone in your arms or legs,” Messonnier said on Oct. 17 in a press briefing.

“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 our hands, staying up to date on recommended vaccines and using insect repellent to prevent mosquito bites,” she said.

Dr Robert Redfield, director of the CDC, told CBS that AFM doesn’t appear to be transmissible from human to human.

What Happens in AFM?

AFM symptoms tend to begin about a week after a viral infection like a common cold or fever. The condition affects the spinal cord and nervous systems, and causes muscle weakness on one or both sides of the body—usually in the arms or legs.

AFM can also affect the muscles in a person’s face, neck, and back. Patients can have Polio-like symptoms such as facial drooping and difficulty swallowing. The muscle weakness can progress to paralysis.

Dr Fernando Acosta, a pediatric neurologist in Fort Worth, Texas, said that AFM can present differently across patients depending on the location of the body it affects.

AFM appears to attack gray matter in the spinal cord, which is what causes the body’s muscles to weaken.

“If [AFM affects gray matter] lower in the spinal cord, [the paralysis will] be more in the legs, and if it’s higher up, it’ll be more in the arms,” Acosta told the Daily Mail. “Or if it’s closer to the neck, they can’t move head, neck and shoulders. We had one case of that and that was just awful.”

Mostly in Children, But Most Will Recover

The CDC starting tracking reports of AFM after an outbreak in Colorado in August 2014. It has since confirmed a total of 396 cases across the country. More than 90 percent of these cases have been in children under the age of 18. The average age of those affected has been four years old.

There have been no recorded deaths in 2018 from the disease, and since 2014, the CDC knows of only one death in 2017, according to Messonnier.

Dr Frank Esper, a pediatric infectious disease expert in Cleveland, Ohio, said that many children will recover quickly on their own.

“I think it’s also very reassuring that many of these children do better very quickly after—they get very weak very quick—but then they get better very quick; the majority of them go that way,” he told Fox News.

However, a significant number of patients will need ongoing physical therapy to regain strength, Esper told WKYC.

At present, there is no specific treatment protocol for AFM—it is being dealt with on a case-by-case basis. There are no known medications to shorten the duration of the illness or reverse its effects.

In most cases, however, doctors will recommend physical or occupational therapy to help with muscle weakness.

“Unfortunately, right now there is no established treatment [for AFM],” Dr. Christos Karatzios at the Montreal Children’s Hospital in Canada told CTV News.

“The treatment is supportive. Patients, if they can’t breathe, they are supported with ventilator… If they cannot feed themselves, then they may be fed either through the nose or through the mouth with a tube down directly into the stomach… (And) there are patients being treated with high dose steroids or intravenous antibodies.”

Still A Mystery

The number of AFM cases in the United States has mysteriously peaked around late summer and fall, at an interval of every two years since the CDC started monitoring in 2014.

No other countries have yet detected similar seasonal biannual increases in AFM prevalence, according to Messonnier. 


AFM polio-like cases according to CDC since 2014 graph
The CDC has confirmed 396 cases since an outbreak in Colorado in August 2014, almost all of them in children. (CDC)

AFM is currently being diagnosed via MRI. Some doctors also run a spinal tap to test spinal fluid.

“When you do investigations and you do an MRI of the spinal cord, there’s a very distinctive abnormality in what we call the grey matter or the anterior horn cell of the spinal cord,” Dr. Jeremy Friedman, a pediatrician, told CTV News.

However, an MRI cannot determine the cause of AFM, Esper told WKYC, and according to the CDC, the condition remains a mystery in many regards.

“We don’t know what caused the increase in AFM cases starting in 2014. We have not yet determined who is at higher risk for developing AFM, or the reasons why they may be at higher risk,” the CDC website reads. “We do not yet know the long-term effects of AFM.”

New Polio-Like Disease?

However, a group of doctors believes that AFM is linked to a virus called enterovirus D68, or EV-D68.

“I think we are seeing the emergence of a new polio-like paralytic disease. Its pattern and most of the evidence that we have suggests that it is likely a virally caused disease,” Dr. Ken Tyler, a neurologist at the University of Colorado School of Medicine, told NBC News.

“I think the leading candidate is enteroviruses in general and EV-D68 in particular.”

While “Polio-like” is a common term used to describe AFM, the CDC has said that no poliovirus has ever been found in AFM-confirmed cases.

It is also possible that AFM could be attributed to an abnormal immune response to the initial viral infection.

Messonnier acknowledges that enterovirus has been the cause of several individual AFM cases, but this hasn’t been true in all cases to provide a “unifying diagnosis,” she said.

“AFM can be caused by other viruses, such as enterovirus and west nile virus, environmental toxins and a condition where the body’s immune system attacks and destroys body tissue that it mistakes for foreign material. While we know that these can cause AFM, we have not been able to find a cause for the majority of these AFM cases,” Messonier said.


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