Reemergence of Enterovirus 71 Epidemic in Northern Taiwan, 2012

Abstract

BackgroundEnterovirus 71 (EV71) belongs to picornavirus family and could be classified phylogenetically into three major genogroups (A, B and C) including 11 genotypes (A, B1-B5 and C1-C5). Since 1997, EV71 has caused large-scale of epidemics with neurological complications in Asian children. In Taiwan, nationwide EV71 epidemics with different predominant genotypes have occurred cyclically since 1998. A nationwide EV71 epidemic occurred again in 2012. We conducted genetic and antigenic characterizations of the 2012 epidemic.MethodsChang Gung Memorial Hospital (CGMH) is a medical center in northern Taiwan. In CGMH, specimens were collected from pediatric inpatients with suspected enterovirus infections for virus isolation. Enterovirus isolates were serotyped and genotyped and sera from EV71 inpatients were collected for measuring neutralizing antibody titers.ResultsThere were 10, 16 and 99 EV71 inpatients identified in 2010, 2011 and 2012, respectively. There were 82 EV71 isolates genotyped, which identified 17 genotype C4a viruses and 65 genotype B5 viruses. The genotype B5 viruses were not detected until November 2011 and caused epidemics in 2012. Interestingly, the B5-2011 viruses were genetically distinguishable from the B5 viruses causing the 2008 epidemic and are likely introduced from China or Southeastern Asia. Based on antigenic analysis, minor antigenic variations were detected among the B5-2008, B5-2011, C4a-2008 and C4a-2012 viruses but these viruses antigenically differed from genotype A.ConclusionsGenotype B5 and C4a viruses antigenically differ from genotype A viruses which have disappeared globally for 30 years but have been detected in China since 2008. Enterovirus surveillance should monitor genetic and antigenic variations of EV71.

A Molecular Approach Applied to Enteroviruses Surveillance in Northern Taiwan, 2008-2012

“…EV71 seems to evolve quicker in the past 15 years and different EV71 genotypes have caused large-scale epidemics in tropical and subtropical Asia since 1997. Moreover, antigenic variations among different genotypes were observed based on serum neutralization test using rabbit and human antisera [23–27]. Based on the VP1-CODEHOP test, we found that multiple EV71 genotypes co-circulated in 2008–2012 but EV71 sub-genotypes B5b and B5c caused large-scale epidemics in 2008 and 2012, respectively, which are consistent with other studies analyzing full VP1 sequences and complete genomes [24, 27].…”

“…Moreover, antigenic variations among different genotypes were observed based on serum neutralization test using rabbit and human antisera [23–27]. Based on the VP1-CODEHOP test, we found that multiple EV71 genotypes co-circulated in 2008–2012 but EV71 sub-genotypes B5b and B5c caused large-scale epidemics in 2008 and 2012, respectively, which are consistent with other studies analyzing full VP1 sequences and complete genomes [24, 27]. Although a degenerate primer set targeting conserved region of enteroviruses (5’-UTR) had been widely used on molecular diagnostic systems, the 5’-UTR-based molecular diagnosis cannot precisely identify serotypes of human enteroviruses [8, 28].…”

Molecular epidemiology of human enterovirus 71 at the origin of an epidemic of fatal hand, foot and mouth disease cases in Cambodia

“…4 Genotype B has five subgenotypes and has been circulating in Asia, particularly in Malaysia and Singapore, since the 1970s. 10 Subgenotype B5 was reported during recent outbreaks in Thailand, 11, 12 Taiwan 13, 14 and Vietnam. 15 Genotype C also comprises five subgenotypes.…”

Effect of enterovirus infections on asthma in young children: A national cohort study

“…This system includes more than 250 sentinel clinics and hospitals located nationwide . In Taiwan, the diagnosis of EV is based on positive isolates of EVs from throat swabs, rectal swabs or cerebrospinal fluid; serologic assays; and clinical and laboratory definitions in the hospital‐based surveillance system. To avoid diagnosis bias in the physician‐based system, each sentinel physician collects 2‐5 throat swabs each week from patients with herpangina or hand‐foot‐mouth disease (HAMD) within 3 days of disease onset, even without the appearance of severe symptoms .…”