Enterovirus 68 among children with severe acute respiratory infection, the Philippines

Abstract

Enterovirus 68 (EV68) is a rare enterovirus associated with respiratory illness that, unlike other enteroviruses, has been identified only from respiratory specimens. We identified EV68 from respiratory specimens of children hospitalized with a diagnosis of severe pneumonia in Leyte, Republic of the Philippines. Twenty-one samples showed high similarity with EV68 by sequencing of 5' nontranslated region; 17 of these samples were confirmed as EV68 by sequencing of viral protein 1 capsid coding region. Most previously reported EV68 cases had been identified as sporadic cases. All 21 patients we identified had severe illness, and 2 died, possibly the first reported fatal cases associated with EV68 infection. Our study suggests that EV68 may be a possible causative agent of severe respiratory illnesses.

Figure 1

Phylogenetic trees of selected enterovirus (EV) 68 strains, based on the nucleotide sequence of 2 genomic regions: A) partial 5′ nontranslated region and B) partial viral protein 1. EV68 strains analyzed in this study are indicated by black circles. Phylogenetic analysis was performed by using nucleotide alignments and the neighbor-joining method, as implemented in MEGA software (www.megasoftware.net). Poliovirus 1, EV70, and EV94 sequences were used as outgroups. Scale bar indicates number of nucleotide substitutions per site.

Figure 2

Geographic distribution of residences of patients in whom enterovirus 68 was detected in the Philippines, May 2008–May 2009. A) Eastern Visayas Region in the Philippines; B) expanded Eastern Visayas Region. Address information was obtained from parents of the children. Locations for 6 patients were unknown.

Figure 3

Temporal and geographic distribution of enterovirus (EV) 68 cases in Eastern Visayas Region in the Philippines, May 2008–May 2009. Address information was obtained from parents of the pediatric patients. The graph shows the number of reported EV68 cases of each week in Eastern Visayas Region, and a report from a different city in the region is indicated with a bar of different color. The weeks with no bars indicate no reported cases of EV68.