Hospitals in the mid-Western USA are seeing an abnormally high number of children with severe respiratory illness. From August to September 16, 2014, a total of 130 people in 12 states (Alabama, Colorado, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Missouri, New York, Oklahoma, Pennsylvania) were confirmed to have illness caused by enterovirus D68 (EV-D68).1 In the Delaware Valley, there were four confirmed cases at the Children’s Hospital of Philadelphia and at least 12 suspected cases in Delaware (all in hospitalized children) awaiting confirmation by the Centers for Disease Control (CDC).2 Other states awaiting sample confirmation include Washington, Michigan, Georgia, Ohio, and Utah.3,4
Enteroviruses are members of the picornavirus family, a large group of non-enveloped RNA viruses that also include rhinoviruses (a cause of the common cold) and polioviruses, among others. EV-D68 can cause mild to severe respiratory illness. Symptoms consist of a runny nose, sneezing, cough, fever, and muscle aches. Because many of these symptoms mimic those of the common cold, EV-D68 disease is difficult to diagnose without testing for the presence of the virus. More severe disease symptoms include difficulty breathing and wheezing, and can require intensive care at a hospital. Children and those with asthma are at greatest risk for severe disease. EV-D68 spreads from person to person through the air much like cold and flu viruses, when an infected person coughs or sneezes. It can also be spread by touching contaminated surfaces.
EV-D68 was first isolated in San Diego, California in 1962 from four children with bronchiolitis and pneumonia.5 Since its discovery it has rarely been reported. From 1970-2005 only 26 clinical isolates of EV-D68 were reported in the USA, representing only 0.1 % of all enterovirus isolates collected.6 That said, the CDC does not really know how many infections from EV-D68 occur each year in the United States, as reporting is not required and any data that the CDC receives are voluntarily provided by doctors.
However, even before this 2014 outbreak, other clusters of EV-D68 infections in recent years have implicated it as an emerging respiratory pathogen.7 Between 2008-2010, six clusters of respiratory illness associated with EV-D68 occurred in Japan, the Philippines, the Netherlands, and the USA (Georgia, Arizona, Pennsylvania).8 Of the 180 confirmed cases during this outbreak, two in the Philippines and one in Japan were fatal; in all countries, a majority of the cases required hospitalization. Interestingly, although 10 of the 11 pediatric cases of EV-D68 identified in Japan had underlying health issues (asthmatic bronchitis or pneumonia), the lone fatal case occurred in an otherwise healthy 4 year old boy with no underlying disease. Overall, deaths from EV-D68 infection are thought to be rare.
EV-D68 has also been implicated in recent incidents of paralysis. From August 2012 – July 2013, five children in California were diagnosed with paralysis and severe muscle weakness.9 Doctors ruled out polio, although two of the five children tested positive for EV-D68 (which, as mentioned above, is related to polioviruses). The California Department of Public Health have identified 20 similar cases of non-polio paralysis but so far no causative agent has been identified.
There are no antiviral medications available and no vaccine against EV-D68. Over-the-counter medications can be taken for pain and fever (although aspirin should not be given to children). People with severe respiratory illness may need to be hospitalized and require mechanical ventilation. Disease prevention methods are the same as those for other respiratory viruses: wash your hands often with soap and water; avoid touching your eyes, nose, and mouth; sneeze and cough into your sleeve, not your hands; avoid kissing, hugging, and sharing cups or eating utensils with people who are sick; and disinfect frequently touched surfaces.
References/ Further Reading:
5. Schieble JH, Fox VL, Lennette EH. 1967. A probable new human picornavirus associated with respiratory disease. Am J Epidemiology. 85:297-310.
6. Khetsuriani N, et al. 2006. Enterovirus surveillance – United States, 1970–2005. MMWR Surveill Summ. 55:1-20.
7. Tokarz R, et al. 2012. Worldwide emergence of multiple clades of enterovirus 68. J Gen Virol. 93:1952-1958.