New Viral Threats
Enterovirus D68 (EV-D68) is not new. One of over 100 types of enteroviruses, it was first identified in 1962 in California. An MMWR report published in September summarized the statistics. EV-D68 had only rarely been reported in the United States. In the 5 years between 2009 and 2013, there were 79 reported cases. As of September 11, 2014, a total of 82 cases across six mid-Western states had been reported just this year, and within a few weeks, 538 cases had been reported in 43 states.
A history of asthma appears to be a risk factor for EV-D68 infection. The median age of affected children is approximately 6 years. Initial symptoms of severe respiratory illness can progress to respiratory distress necessitating pediatric intensive care admission and, in some cases, bilevel positive airway pressure ventilation or mechanical ventilation. Because there is no vaccine against EV-D86 and no specific treatment, management is limited to supportive measures. Prevention is the standard antiviral approach: hand-washing, avoidance of hand contact with the face, and no sharing of cups or eating utensils with sick individuals.
Not to be outdone by a respiratory virus, a mysterious neurologic illness producing acute flaccid paralysis was described by the CDC in October. Characterized by spinal cord gray-matter abnormalities and focal limb weakness, the illness began to garner attention in Colorado in September 2014. By November, the CDC had verified reports of 88 cases in 32 states. Further investigation tied the Colorado cases to a cluster of cases from California reported between 2012 and 2014. Typical symptoms in the clusters included extremity weakness; cranial nerve dysfunction; some neck, back, or extremity pain; and no changes in either sensation or mental status.
And now for the strange part: The jury is still very much out on whether or not these two phenomena are related. In September, the CDC reported that of nine patients with acute flaccid paralysis, four tested positive for EV-D68. In an interview with Medscape, Daniel Feikin, MD, of the CDC's Epidemiology Branch, acknowledged that "we don't know if these neurologic cases are related to EV-D68. Detection of the enterovirus in those with neurologic illness might be coincidental."
As of the time of this writing, talk of EV-D68 and mysterious neurologic illnesses has faded somewhat from the headlines (now that the influenza season is upon us). Nonetheless, this will be an interesting story to follow as the virologists and epidemiologists continue to ask questions and probe the details of these disease clusters.