title: Molecular epidemiology and evolution of human enterovirus serotype 68 in Thailand, 2006-2011.
abstract: BACKGROUND
  Publications worldwide have reported on the re-occurrence of human enterovirus 68 (EV68), a rarely detected pathogen usually causing respiratory illness. However, epidemiological data regarding this virus in particular on the Asian continent has so far been limited.
  
  
  RESULTS
  We investigated the epidemiology and genetic variability of EV68 infection among Thai children with respiratory illnesses from 2006-2011 (n = 1810). Semi-nested PCR using primer sets for amplification of the 5'-untranslated region through VP2 was performed for rhino-enterovirus detection. Altogether, 25 cases were confirmed as EV68 infection indicating a prevalence of 1.4% in the entire study population. Interestingly, the majority of samples were children aged >5 years (64%). Also, co-infection with other viruses was found in 28%, while pandemic H1N1 influenza/2009 virus was the most common co-infection. Of EV68-positive patients, 36% required hospitalizations with the common clinical presentations of fever, cough, dyspnea, and wheezing. The present study has shown that EV68 was extremely rare until 2009 (0.9%). An increasing annual prevalence was found in 2010 (1.6%) with the highest detection frequency in 2011 (4.3%). Based on analysis of the VP1 gene, the evolutionary rate of EV68 was estimated at 4.93 × 10(-3) substitutions/site/year. Major bifurcation of the currently circulating EV68 strains occurred 66 years ago (1945.31 with (1925.95-1960.46)95% HPD). Among the current lineages, 3 clusters of EV68 were categorized based on the different molecular signatures in the BC and DE loops of VP1 combined with high posterior probability values. Each cluster has branched off from their common ancestor at least 36 years ago (1975.78 with (1946.13-1984.97)95% HPD).
  
  
  CONCLUSIONS
  Differences in epidemiological characteristic and seasonal profile of EV68 have been found in this study. Results from Bayesian phylogenetic investigations also revealed that EV68 should be recognized as a genetically diverse virus with a substitution rate identical to that of enterovirus 71 genotype B (4.2 × 10(-3 )s/s/y).
authors.affiliation: Chulalongkorn University, Bangkok, Thailand.
authors.forename: Piyada
authors.initials: P
authors.lastname: Linsuwanon
authors.forename: Jiratchaya
authors.initials: J
authors.lastname: Puenpa
authors.forename: Kamol
authors.initials: K
authors.lastname: Suwannakarn
authors.forename: Vittawat
authors.initials: V
authors.lastname: Auksornkitti
authors.forename: Preeyaporn
authors.initials: P
authors.lastname: Vichiwattana
authors.forename: Sumeth
authors.initials: S
authors.lastname: Korkong
authors.forename: Apiradee
authors.initials: A
authors.lastname: Theamboonlers
authors.forename: Yong
authors.initials: Y
authors.lastname: Poovorawan
mesh_terms: D020121:5' Untranslated Regions / Q000235:genetics; D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D060085:Coinfection; D030016:Enterovirus D, Human / Q000145:classification / Q000235:genetics / Q000302:isolation & purification; D004769:Enterovirus Infections / Q000453:epidemiology* / Q000235:genetics*; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D053118:Influenza A Virus, H1N1 Subtype / Q000235:genetics / Q000302:isolation & purification; D007251:Influenza, Human / Q000453:epidemiology / Q000235:genetics; D008297:Male; D017720:Molecular Epidemiology; D010802:Phylogeny; D012703:Serotyping; D013785:Thailand / Q000453:epidemiology; D014764:Viral Proteins / Q000235:genetics
chemical_list: D020121:5' Untranslated Regions; D014764:Viral Proteins