Molecular epidemiology of the 2005 enterovirus 71 outbreak in central Taiwan

Background: Since 1998, Taiwan has experienced annual outbreaks of enterovirus 71 (EV71) nationwide. The area around Taichung City experienced a particularly large outbreak in 2005, after which EV71 disappeared for 2 y before re-emerging in 2008. Here we present the clinical, genotypic, and epidemiological baseline data for the 2005 Taichung outbreak. Methods: Throat swab, stool and cerebrospinal fluid samples were collected and stored in viral transport medium. Samples were tested by reverse-transcriptase polymerase chain reaction and viral culture. Epidemiological, laboratory, and clinical data were extracted from medical record reviews. A total of 27 virus isolates were selected for phylogenetic analysis. Results: Confirmed phylogenetic results of the viruses were separated into 5 groups. The 5'-UTR regions served as a focus for investigating genetic relationships among the 27 EV71 isolates, all of which belonged to a distinct clade in the C4 genotype. Most of the strains belonged to 5 observed epidemic groups. Conclusion: In conclusion, the 2005 outbreak in central Taiwan was caused by divergent EV71 strains belonging to the C4 genotype.