Recent Spike in Acute Flaccid Myelitis Cases
As of September 2016, there have been 89 cases of Acute Flaccid Myelitis (AFM) across 33 states in the United States (1). There has been a recent spike of cases reported in five counties in Washington State, in which eight children have been hospitalized for AFM. The Washington State Department of Health reported that five children have been released, with three children remaining hospitalized as of November 4th, 2016 (3). The Department of Health is currently investigating the recent surge of cases, but have found no known cause as of yet.
What is Acute Flaccid Myelitis?
AFM is an illness that affects the nervous system, particularly the spinal cord (2). Symptoms of AFM include: facial and eyelid droop/weakness, difficulty moving the eyes, swallowing or speech, loss of muscle tone, and muscle weakness (2). The most detrimental symptom of AFM is respiratory failure, which occurs with the weakening of breathing muscles (2). Patients who experience respiratory failure may require a ventilator machine to help them breathe.
AFM can be caused by a variety of illnesses, such as enteroviruses (polio and non-polio), West Nile virus, and adenoviruses (2). AFM can be diagnosed through magnetic resonance imaging (MRI), testing nerve responses, and testing of cerebrospinal fluid (2). There is no effective treatment or vaccine for AFM. The best way to prevent AFM is by preventing the illnesses that cause it. This includes staying up to date with vaccinations against polio, using protective measures against mosquitoes to prevent West Nile virus, and practicing proper sanitary precautions, like hand-washing (2).
Acute Flaccid Myelitis in the United States
Because 2014 was the first year in which reported cases of AFM have been documented, there remain limitations in the ability to assess trends in AFM. From August to December 2014, there were 120 confirmed cases of AFM (2). These cases occurred simultaneously during an Enterovirus D-68 outbreak (2). However, there were no reported cases of Enterovirus D-68 in 2015 and only a few sporadic cases in 2016, indicating no clear association between Enterovirus D-68 and the recent increase in AFM (2). The cause of the 2014 outbreak remain unknown. In 2015, there were only 21 reported cases of AFM (2). However, reporting of cases are not mandatory in every state, which may affect the representation of the actual number of cases in the United States (2).
While the number of reported cases so far in 2016 is less than in 2014, the Center for Disease Control is still concerned about the recent increase in AFM in the past few months. There is still no known source of this most recent AFM outbreak. What is known is that most of the cases have been children between the ages of 3 and 14 years old and mostly reside in Washington State (1). The Center for Disease Control is investigating this outbreak and will hopefully determine a cause of this cluster of AFM cases.