CDC: Cases of polio-like disease, mostly among children, continue to rise

The number of confirmed and suspected cases of the polio-like disease acute flaccid myelitis as well the number of states reporting cases continue to rise in the United States, according to the Centers for Disease Control and Prevention’s weekly report.

“As of today, we have 252 patients under investigation, which is an increase of 33 patients under investigation since last week,” said Dr. Nancy Messonnier, director for the National Center for Immunizations and Respiratory Diseases, during a telebriefing Tuesday with reporters.

“We have confirmed an additional 10 cases to bring the total confirmed AFM case count to 90 in 27 states. So far there have been no deaths among AFM patients reported to CDC in 2018.”

The number of states reporting cases for the prior week was 25.

Although a rare condition, the CDC began to release weekly reports in October of patients under investigation for it after noting an increase starting in August as certain seasonal viruses begin to circulate.

There have been 414 confirmed cases of AFM since the CDC began tracking it in 2014.

Messonnier stressed in her briefing that the cause of the disease remains unknown. It has been compared to poliomyelitis because its symptoms can include limb paralysis.

Messonnier noted that while some patients “fully recover” from AFM she said “at least half of the patients don’t recover” from all symptoms.

“And some of those patients have actually really serious swelling,” Messonnier said.

“Unfortunately, we have not been following every AFM patient. It’s a gap in our understanding of AFM that we don’t understand the long-term consequences in every patient. And it’s something we’re going to be really looking at really closely, both for the patients this year and also to follow up the patients that have gotten AFM in previous years.”

There is no specific clinical management for the disease that involves the expertise of both infectious disease specialists and neurologists and it can take the CDC “a week to a few weeks,” Messonnier said, to classify and confirm suspected cases sent by state health departments.

AFM is said to affect the body’s nervous system, causing inflammation in the spinal cord and interfering with the transmission of nerve signals to and from the brain.

It is defined by the Council of State and Territorial Epidemiologists as a “rare and very serious condition that affects the nervous system causing weakness in the arms or legs and is, in some instances, also associated with long-term disability.”

It can be diagnosed through spinal cord fluid and an MRI, but Messonnier noted in her briefing that spinal cord fluid tested negative in the majority of cases of children recently diagnosed with AFM. Evidence of a virus was found more often in respiratory and stool samples.

Messonnier said of the 80 confirmed cases through Nov. 5, “Most were children; particularly between 2 and 8 years old; about half were male; almost all reported fever and/or respiratory illness in the three to 10 days before limb weakness” and that in “almost all patients, an upper limb was involved” and that “about half had only upper limb involvement.”

“CDC has tested 125 spinal cord fluid respiratory and stool specimens from 71 of the 80 confirmed AFM cases. Of the respiratory and stool specimens tested, about half were positive for enterovirus or rhinovirus, including EVA-71 and EVD-68,” Messenger said.

“The spinal cord fluid was positive in two cases. One had evidence of EVA-71, and one had evidence of EVD-68. One of the cases was in an adult who was on immune-suppressive medication and the other was in a child who had very rapid progression of paralysis.”

She added, “It is important to put these two cases in context.”

“Since 2014, we have tested spinal cord fluid of most AFM cases, and in only a few have we identified a pathogen. When a pathogen is found in the spinal fluid, it is good evidence that it was the cause of a patient’s illness,” Messenger said.

“However, oftentimes, despite extensive testing, no pathogens are found in the spinal fluid. This may be because the pathogen has been cleared by the body or it is in hiding in tissues that make it difficult to detect.”

She added, “Another possibility is that the pathogen triggers an immune response in the body that causes damage to the spinal cord.”

“Polio testing nowadays certainly doesn’t look at spinal fluid, because we know that finding polio in the gastrointestinal track tells us that a patient has polio,” Messonnier said.

“We haven’t yet figured out AFM to understand completely what the significance is in finding it in respiratory specimens.”

She added, “We know that most patients with AFM have fever and/or respiratory symptoms before developing AFM.”

“However, at this time of year, many children have fever and respiratory symptoms. Most of them do not go on to develop AFM,” Messonnier said.

She said the CDC is “broadening our hypotheses” in terms of causes and that more sophisticated testing may be needed to find the cause at the point the illness occurs.

She added, “It is important for parents to realize that this still is a relatively rare condition.”

“If parents have concerns about their child, they should reach out quickly to their physician and get their child evaluated,” Messonnier said.

Messonnier said “so far, the curve from 2018 looks similar to 2016 and to 2014” when asked to predict the number of AFM confirmed cases for this year.

The highest number of confirmed cases in recent years were 120 in 2014 in 34 states and 149 in 2016 in 39 states.

In 2017, CDC received information for 33 confirmed cases of AFM in 16 states across the U.S.