The every-other-year acute flaccid myelitis (AFM) outbreak in children looks to become even more complicated during the COVID-19 pandemic, and early reporting and follow-up by healthcare providers is critical, the CDC said on Tuesday.
“This could be another outbreak for clinicians, parents and children to deal with,” on top of flu, the COVID-19 pandemic, and other respiratory illnesses, said CDC Director Robert Redfield, MD, on a conference call with reporters.
He emphasized that “timing is critical” for AFM and delays in recognition and care could put patients at risk. Cases generally appear from August to November, he noted.
AFM, with symptoms resembling polio, was first noticed in 2012, although a subsequent retrospective analysis found potential cases as far back as 2005. It is believed to be a viral illness, although no one agent has been identified as the cause; in about half of cases examined in 2018, no virus was detected. Poliovirus, however, has been definitely excluded as a cause. The most common suspect is an enterovirus called EV-D68, but its frequency and exact role remain uncertain. West Nile virus and certain adenoviruses are also potential causes.
Significant outbreaks occurred in 2014, 2016 and 2018, each larger than the last (possibly due to greater recognition). Well over 200 cases were diagnosed in 2018. A few have been seen in odd-numbered years but the biennial peaks appear to be a real phenomenon, though unexplained. That puts 2020 squarely in the crosshairs.
“Clinicians should suspect AFM in patients with sudden limb weakness, recent respiratory illness or fever and presence of neck or back pain or any neurological symptoms,” Redfield said.
Early recognition enables patients to be quickly hospitalized, monitored for signs of deterioration, specimen collection and appropriate imaging, such as MRI. It also distinguishes AFM cases from “other conditions that cause limb weakness,” he added.
Redfield noted AFM is a medical emergency that requires immediate care and monitoring and “clinicians should not delay in hospitalizing patients.”
Thomas Clark, MD, deputy director of CDC’s division of viral diseases, said the COVID-19 pandemic may keep AFM cases from being recognized.
“We are concerned that parents might be worried about taking their child to the doctor if they developed something as serious as limb weakness,” he said.
When MedPage Today asked if this could potentially complicate school reopenings, in light of the pandemic, Redfield said AFM does not occur on a scale that would make it a factor.
“I want to stress this is a very rare event, but a very serious event when it occurs in a family,” he said.
Clark added it is “an uncommon outcome of very common respiratory illnesses” and encouraged similar public health interventions that are being stressed in school reopening guidelines, such as careful handwashing, “cough etiquette” and sanitizing high-touch surfaces.
CDC researchers shed some light on the 2018 AFM outbreak in a Vital Signs edition of the Morbidity and Mortality Weekly Report.
In that year, 238 patients from 42 states were diagnosed with confirmed AFM. Median age was about 5; 58% were boys and 53% were white. Importantly, 98% of patients were hospitalized, over half were admitted to an intensive care unit and 23% required intubation and mechanical ventilation.
Nearly all patients presented with fever, respiratory illness or both a median of 6 days prior to onset of limb weakness. Other common clinical symptoms included gait difficulty (52%), neck or back pain (47%), fever (35%) and limb pain (34%).
Among types of virus identified, EV-D68 was the most common (n=34), followed by EV-A71 (n=12). Patients with EV-D68 were more likely to be older, and have a prodromal respiratory illness. They noted while abnormal findings on brain MRI were less common among those with EV-D68, a higher proportion were admitted to an ICU and required mechanical ventilation.
By definition, all patients with confirmed AFM had “at least one abnormal spinal cord MRI indicating predominantly gray matter lesions.” Among those who received MRIs, cervical cord lesions were the most common (94%), followed by thoracic cord lesions (86%). Brain stem lesions were observed in 100 of 227 patients who received a brain MRI, researchers noted.
Notably, poliovirus was not detected in any of the cases, researchers said.
Clark urged all clinicians to “collect specimens early” and report AFM cases to their state or local health department. He also added the importance of “early and aggressive physical therapy” and occupational therapy when kids are recovering from this illness.
“We are prepared for an AFM outbreak this year, and it will be starting soon if it’s consistent with previous years,” he said.
Two co-authors have been issued U.S. patent numbers for kits including VP1 and VP3 nucleic acid molecules, and one co-author has been issued a patent for detection and identification of parechoviruses.