As of 3 October 2014, 43 states and the District of Columbia have reported 538 cases (+325 since 23 September 2014) of Enterovirus D68 (EV-D68) to the U.S. Centers for Disease Control and Prevention (CDC). Most of the cases have been identified among children; however, one case was identified in an adult. This outbreak was first announced in a media conference held on 8 September 2014. In this announcement, the CDC stated that EV-D68 was detected in clusters of individuals with respiratory illness in Kansas City, Missouri and Chicago, Illinois. Many of the initial identified cases had a history of asthma or wheezing. Recent increases in cases can be attributed to awareness of this issue among health officials and the amount of time necessary for disease investigation and confirmation. Current surveillance tools for influenza-like illness may not be appropriate for the detection of EV-D68 because many of the identified cases failed to develop fever. The CDC is involved in the ongoing investigation of a possible link between EV-D68 and acute paralysis. Furthermore, the CDC has identified EV-D68 in specimens from patients who have died, but the role of EV-D68 in these deaths remains unclear. EV-D68 has rarely been reported in the U.S. since first recognized in California in 1962. Enterovirus infections are not reportable in the U.S., so the illness is likely underreported because most enterovirus infections are self-limiting and do not require medical attention. The CDC estimates that non-polio enteroviruses are very common and are responsible for 10 to 15 million U.S. infections each year.

EVENT FEATURES

• As of 3 October 2014, the U.S. Centers for Disease Control and Prevention (CDC) had confirmed Enterovirus D68 (EV-D68) cases in 43 states and the District of Columbia affecting 538 (+325 since 23 September 2014) people. The affected regions include Alabama, Arkansas, California, Colorado, Connecticut, Delaware, District of Columbia, Georgia, Idaho, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maine, Maryland, Massachusetts, Michigan, Minnesota, Mississippi, Missouri, Montana, Nebraska, New Hampshire, New Jersey, New Mexico, New York, North Carolina, North Dakota, Ohio, Oklahoma, Pennsylvania, Rhode Island, South Carolina, South Dakota, Texas, Utah, Vermont, Virginia, Washington, West Virginia, Wisconsin, and Wyoming.

• The CDC is prioritizing testing of specimens from children with severe respiratory illness; there may be more children infected with EV-D68 with milder illness that have not yet been identified.

• Similar to the initial clusters, many of the children confirmed to be infected with EV-D68 have a history of asthma or wheezing.

• Media and state public health reports have indicated that three additional states may be involved in the current EV-D68 outbreak. Increased respiratory cases under investigation are reported to be in Alabama, Tennessee, and Oregon.

• Numerous hospitals and local jurisdictions are reporting an increase in respiratory illness activity in children. Not all clusters or cases in clusters have tested positive for the presence of EV-D68. Only about half of the specimens submitted to the CDC have been positive for EV-D68; an estimated one-third of specimens have been positive for other enteroviruses/rhinoviruses.

• In a media conference held on 8 September 2014, the CDC announced the first 30 cases confirmed positive of EV-D68 in Chicago, IL and Kansas City, MO. Several more cases remain under investigation as reported by state public health departments and the media.

o Sequencing of nasophaygenal specimens from patients in Chicago, IL and Kansas City, MO confirmed that 30 patients, ages six months to sixteen years, from the two locations were positive for EV-D68.

o Of those patients confirmed to be infected with EV-D68 from both locations, 21 (70%) of them are reported to have a history of asthma or wheezing and only seven (23.3%) patients are presenting with a fever. Twenty-nine of the confirmed patients have been admitted to pediatric intensive care for respiratory distress. Eight patients require artificial ventilation.

• On 29 August 2014, the Missouri Health Department issued a health alert noting an increase in respiratory illnesses in children at hospitals in Kansas City and St. Louis.

• On 23 August 2014, the University of Chicago Medicine, Comer Children’s Hospital, in Chicago, IL, notified the CDC of an increased number of patients hospitalized with severe respiratory symptoms.

• On 19 August 2014, the Children’s Mercy Hospital in Kansas City, MO notified the CDC of an increased number of patients hospitalized with severe respiratory symptoms. Similarly, laboratory surveillance detected an increase in nasopharyngeal specimens collected from 5-19 August 2014 testing positive for rhinovirus/enterovirus.

Possible link between EV-D68 and unexplained paralysis

• Media reports recognize cases of paralysis possibly linked to EV-D68 in an additional six states beyond those reported by the CDC. These states are Alabama, New York, Michigan, Missouri, Rhode Island, and Virginia.

• On 12 September 2014, the Colorado Department of Public Health notified the CDC of a cluster of nine children, aged 1-18 years, with acute neurologic illness onset between 8 August and 15 September 2014. All of these children suffered fever, most with accompanying respiratory symptoms, 3-16 days prior to the onset of neurologic illness. While nasopharygngeal specimens in six of eight patients tested were positive for rhinovirus/enterovirus, no enterovirus was identified in the cerebrospinal fluid (CSF). Of those six specimens from patients positive for enterovirus, only four typed as EV-D68.

o On 19 September 2014, the Colorado Department of Public Health released a health alert to inform clinicians of a cluster of children with acute neurologic illness and requested reports of any similar cases within the state. One additional case was reported and is under investigation.

o On 26 September 2014, the CDC released a health advisory regarding acute neurologic illness with focal limb weakness of unknown cause in nine children in Colorado. They defined clinical criteria for cases and requested clinicians to report any patients meeting these criteria to their local and state health departments. The case definition is a patient 21 years old or younger with acute onset of focal limb weakness no earlier than 1 August 2014, and a magnetic resonance imaging (MRI) scan suggestive of spinal cord lesion primarily in the grey matter.

o Most of the children in Colorado did show abnormalities in their spinal cord on MRI.

• In August 2012, the California Department of Public Health (CDPH)was contacted by a private local clinician requesting poliovirus testing for an unvaccinated patient with acute flaccid paralysis associated with anterior myelitis and no international travel history during the month prior to symptom onset. Two additional cases with similar symptoms of unknown etiology were reported to the CDPH within two weeks.

o The CDPH posted official alerts for local health departments during December 2012, July 2013, and February 2014 to find additional cases of acute flaccid paralysis and uncover possible etiologies.

o Twenty-three cases of acute flaccid paralysis with anterior myelitis of unknown etiology were identified. The CDPH Viral and Rickettsial Disease Laboratory tested nasopharyngeal swabs, rectal swabs, serum, and CSF specimens from 19 patients. No common etiology was identified among these specimens. EV-D68 was only detected in the upper respiratory tract specimens from two of these patients.