CDC has released a complete summary of AFM cases in 2018, urging clinicians to recognize symptoms, collect specimens, and report suspected cases.
As the prime season for acute flaccid myelitis (AFM) approaches, the US Centers for Disease Control and Prevention (CDC) has released a Vital Signs report in the Morbidity and Mortality Weekly Report detailing the rare polio-like disease that mainly affects children.
Most cases of the disease are reported in the late summer and early fall, with 233 cases confirmed in 41 states in 2018, representing about 42% of the 559 cases reported since 2014, the report noted. Another 26 cases reported in 2018 were classified as probable.
“AFM is a devastating illness for patients and their families,” CDC investigator Adriana Lopez, MHS, told Contagion® in an interview. “This is the first complete summary of all reported 2018 AFM cases, representing the third and largest outbreak since 2014. We’ve seen a seasonal pattern to this illness—most patients develop AFM between August and October. Most patients had a mild respiratory illness or fever less than a week before they developed arm or leg weakness. These are important pieces of evidence that point to viruses, including enteroviruses in particular, playing a role in AFM. CDC and other scientists are continuing to investigate how enteroviruses, including EV-D68, might trigger AFM.”
Upper limb weakness was reported in 42% of cases, and respiratory symptoms or fever were reported with 4 weeks before the onset of limb weakness in 92% of cases.
On average, patients were hospitalized within 1 day of the onset of symptoms, received an MRI within 2 days, and suspected cases were reported to the CDC in 18 days.
“This report provides further insight into patient care and reporting of suspected AFM cases,” Lopez said. “Our data show that patients received the recommended diagnostic work-up and care, including being hospitalized quickly (1 day after limb weakness onset) and receiving MR imaging within 2 days. However, the average time taken to report a suspected AFM case to CDC was 18 days. Rapid reporting helps us to identify and respond to outbreaks early, and alert clinicians and the public. This is the first Vital Signs report about AFM, and it is targeted to health care providers, urging them to recognize AFM and collect specimens early, and rapidly report all suspected cases to the health department.”
Although AFM has been recognized as a complication of infections of West Nile Virus, adenovirus, and enteroviruses, the 2-year cycle of recent cases along with the cluster during late summer and early fall hasn’t been seen before 2014, according to the article.
The median age of those who contracted the disease was 5.3 years old, although it affected patients as young as 6 months and as old as 81.8 years.
Among the confirmed cases, 27% required respiratory support during hospitalization. No deaths were reported during acute illness in 2018, but 2 deaths occurred months later.
Various enterovirus and rhinovirus pathogens were detected among patient specimens, with respiratory specimens having the highest positive yield at 44% and EV-D68 being the most common virus identified. Positive yields from cerebrospinal fluid (CSF) were much less common, appearing in only 2 cases, one each of EV-D68 and EV-A71.
CDC officials expressed their concerns about AFM in an update in October, noting the increase in cases of the polio-like disease and the launch of an investigation to better understand the illness. Specimens were tested for a wide array of pathogens as the CDC explored viruses, environmental toxins, and other potential causes of AFM.
Last year’s outbreak also coincided with a spike in enterovirus A71 in Colorado, which caused an increase in incidences of meningitis and encephalitis. Other likely suspects are EV-D68 and coxsackievirus A16, though the CDC detected these viruses in the spinal fluid of very few patients.
Efforts to understand emerging trends in AFM are ongoing, including monitoring trends, researching possible risk factors, and working to improve lab testing, Lopez told Contagion®. The CDC also is collaborating with the National Institutes of Health on a study to better understand AFM and is conducting surveillance at 7 pediatric hospitals throughout the United States.
Lopez said key priorities identified by the CDC’s AFM Task Force include: