The CDC will begin weekly tracking of cases of acute flaccid myelitis (AFM), the rare polio-like illness affecting mostly children that has been in the headlines since 2014, the agency said.
With increased reports of cases in August and September 2018, the CDC said they are continuing to investigate ongoing cases and will have updated case counts on Monday afternoons on their .
They reported that in 2018, 127 patients were under investigation in 22 states, of which 62 cases have been confirmed. Confirmation in this case requires a specific radiologic finding on an MRI as well as clinical evaluation, as no known pathogen has been identified, they added. Of these confirmed cases, the average age of patients is 4 years, and >90% of cases occurred in children age <18.
In a press briefing, Nancy Messonnier, MD, director of the National Center for Immunization and Respiratory Diseases at the CDC, said that the agency will provide the number of cases under investigation, so "people can better anticipate increases in confirmed cases in the following months."
She characterized acute flaccid myelitis as a rare, but serious illness where some cases recover quickly, while some develop paralysis and require ongoing care. There was one death of a child in 2017.
Acute flaccid myelitis cases have spiked in the late summer and early fall in 2014, 2016, and now 2018, she said, but despite these "peaks of disease," the CDC has been unable to find a "unifying diagnosis." She did say that none of the patients had West Nile virus, so they "do not believe it is causing these cases."
"In several cases, we found enterovirus, and several found rhinovirus," Messonnier said, referring to 2014 and 2016 data. But she added that there has been a "wide variety of causes." She also mentioned environmental toxins and certain conditions within the body's immune system as potential causes under investigation.
"You'd think we'd be finding a single agent," she said. "I am frustrated that despite our efforts, we have not been able to understand the cause of this mystery illness. We don't know who's at higher risk and we don't understand the long-term consequences."
Messonnier said CDC has a for healthcare professionals available on the CDC website, including information on acute flaccid myelitis and instructions for reporting patients under investigation to the state and local health departments.
She also encouraged preventive action, such as handwashing, using mosquito repellent, and keeping children up-to-date on recommended vaccines.