Epidemiological Alert - Acute Flaccid Myelitis associated with enterovirus D68 in the context of Acute Flaccid Paralysis surveillance - 1 November 2017
Situation summary in the Americas and other regions
Although enterovirus cases have been reported sporadically since the 1960s, it was not until August 2014 that the first outbreaks were documented in the United States (1).
Between August and December 2014, the United States Centers for Disease Control and Prevention (CDC) reported an increase in acute flaccid myelitis (AFM) associated with an outbreak of respiratory disease caused by enterovirus (EV) D68 (2,3). Among the 120 AFM cases reported in 34 states, the median age was 7.1 years (range: 4.8-12.1 years), 59% were male, and 81% had respiratory disease before the onset of neurological symptoms (4,5).
Following this event, voluntary surveillance for AFM was initiated in some states, detecting sporadic cases in 2015 and a new increase in cases in 2016 (Figure 1). Cases were also detected in Asia, Canada, and Europe (1).
EV-D68 shares characteristics with rhinoviruses, causing mainly respiratory diseases; however, its role in the pathogenesis of neuroinvasive diseases is not clearly understood.
In 2016, the European Center for Disease Control and Prevention (ECDC) informed that Denmark, France, the Netherlands, Spain, Sweden, and the United Kingdom reported clusters and isolated cases of severe neurological syndromes in children and adults associated with enterovirus infection among which EV-D68 was detected.1 In October 2017, the Argentina International Health Regulations National Focal Point reported a cluster of acute flaccid myelitis (AFM) associated with EV-D68 infection. Between epidemiological week (EW) 13 and EW 21 of 2016, 15 cases of AFM were identified in residents of the provinces of Buenos Aires (13) and Chubut (1 case) and the Autonomous City of Buenos Aires (CABA per acronym in Spanish; 1 case). All cases were in children under 15 years, since the detection occurred in the context of acute flaccid paralysis (AFP) surveillance. This event coincided with the increase in AFP cases in children under 15 years of age observed at the national level between EW 16 and EW 21 of 2016. In 6 of the 15 reported AFM cases, the Regional Poliovirus Reference Laboratory - INEI - ANLIS ”Dr. Carlos G. Malbrán” detected the presence of EV-D68. Positive results were obtained in samples of nasopharyngeal aspirate and in one case the same result was also obtained in a cerebrospinal fluid (CSF) sample. In addition, human EV B and human EV C were detected in stool samples of two of the AFM cases; rhinovirus C in one case and coxsackie virus A13 in one case (7).
Considering the context of polio eradication, 2 the switch from trivalent oral polio vaccine (OPV) to the bivalent OPV since April 2016, that AFM is a type of AFP, and the need to increase knowledge about the role of enteroviruses in the epidemiology of neuroinvasive diseases, the Pan American Health Organization / World Health Organization (PAHO / WHO) reminds Member States that enterovirus is part of the differential diagnosis of AFP.
The following is a series of advice to health authorities regarding surveillance, including laboratory detection.