November 13, 2018
2 min read

CDC: Still working to determine cause behind AFM cases in US

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The CDC announced that the number of acute flaccid myelitis cases has continued to rise in the United States, and most of the patients are young children. The agency has not yet determined the cause of the disease.

As of today, there are 252 patients under investigation for acute flaccid myelitis (AFM) — an increase of 33 patients from a week ago, according to Nancy Messonnier, MD, director of the National Center for Immunization and Respiratory Diseases at the CDC. The agency said there are 90 confirmed cases in 27 states.

Messonnier said there were no deaths reported among patients with AFM to the CDC in 2018. She added that the CDC is asking health departments to match their list of patients with AFM against their death registries.

According to an MMWR, most patients have been children between the ages of 2 and 8 years, and about half have been male. Almost all patients reported fever and/or respiratory illness between 3 and 10 days before developing limb weakness, Messonnier said. In almost all patients, an upper limb was involved.

In the report, 47.5% of patients had upper limb involvement only, 8.8% of patients had lower limb involvement, 15% had two to three upper and lower limbs involved, and 28.8% of patients had all four limbs involved.

Messonnier said at least half of patients do not fully recover from AFM.

“We do not understand the long-term consequences in every patient,” she said.

“We know that most patients with AFM have fever and/or respiratory symptoms before developing AFM,” she said. “However, at this time of year, many children have fever and respiratory symptoms. Most of them do not go on to develop AFM.”

Although the researchers wrote in the MMWR that “clinical, laboratory and epidemiologic evidence to date suggest a viral association,” the CDC said it is still trying to determine the causes of AFM.

Messonnier noted that the CDC has tested 125 spinal cord fluid respiratory and stool specimens from confirmed cases. Of the specimens tested, about half were positive for enterovirus or rhinovirus, including EV-A71 and EV-D68. Spinal cord fluid was positive in two cases — one having evidence of EV-A71 and one having evidence of EV-D68. One of the cases was an adult on immunosuppressive medication. and the other was a child who had very rapid progression of paralysis.

“It is important to put these two cases in context,” Messonnier said. “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 spinal fluid, it is good evidence that it was the cause of the patient’s illness; however, oftentimes, despite intensive testing, no pathogens are found in the spinal fluid.”

The CDC is working to expedite the process to confirm new AFM cases, but “taking care of the patient is the number one priority for doctors and the health department,” she said. ”We want doctors to treat their patients and consult medical experts if necessary, without waiting for the classification results.” – by Bruce Thiel

Disclosure: Messonnier reports no relevant financial disclosures.