infectious diseases
Overview of Enterovirus Infections
Acute flaccid myelitis (AFM)
Enterovirus D68 (EV-D68) causes a respiratory illness, primarily in children; symptoms usually resemble those of a cold (eg, rhinorrhea, cough, malaise, fever in a few children). Some children, particularly those with Asthma , have more serious symptoms involving the lower respiratory tract (eg, wheezing, respiratory distress). Healthy adults can be infected, but they tend to have few or no symptoms. Immunocompromised adults may have severe respiratory disease. Every year, respiratory infections caused by EV-D68 are identified in a few children, and small outbreaks tend to occur every other year. However, larger outbreaks with severe morbidity and some fatalities have occurred. In the late summer and fall of 2014, over 1000 cases were confirmed in a large outbreak across the United States and additional outbreaks were reported worldwide. Severe respiratory distress developed in a significant number of children, and a few children died. At the same time, case clusters of children with focal limb weakness or paralysis with spinal cord lesions (seen on MRI) consistent with AFM after a respiratory illness were also reported; EV-D68 was identified in respiratory specimens in two thirds of cases in two distinct outbreak clusters and in the blood of one child during the progression of the paralysis. Sequenced viruses were nearly identical and shared homology with poliovirus and enterovirus D70, which are known to be associated with acute flaccid myelitis and supports a potential causal role of EV-D68 in AFM paralysis ( References ). Ongoing surveillance by the Centers for Disease Control and Prevention (CDC) detected 120 cases of acute flaccid myelitis in the fall of 2014, coinciding with the EV-D68 outbreak. AFM upsurges occurred in 2014, 2016, and 2018 with 120, 153, and 238 cases reported to CDC each year, respectively, and only 22 and 38 cases reported in the intervening years. These biennial peaks correspond to periods of increased EV-D68 activity (see Overall, these epidemiologic links along with animal model data strongly suggest a causal relationship between EV-D68 infection and AFM ( References ). EV-D68 should be considered as an etiology for otherwise unexplained severe respiratory infection, particularly if associated with a cluster of cases in late summer to fall ( References ; see also Management of AFM should involve neurology and infectious disease specialists. There are a number of treatments that are considered for AFM; however, currently no targeted treatment has enough evidence to endorse or discourage use for the treatment or management of AFM (seeCDC: Clinical Guidance for the Acute Medical Treatment of AFM). 