Etiology and molecular epidemiology of hand, foot and mouth disease in Zhangzhou, 2013-2014

Objective To explore the pathogenic spectrum and molecular epidemiology characteristics of hand foot and mouth disease (HFMD) in Zhangzhou, Fujian province, during 2013-2014 and provide evidence for the prevention and treatment of HFMD. Methods During this period, a total of 1421 samples were collected from clinical diagnosed HFMD cases in sentinel hospitals in Zhangzhou for EV71, Cox A16 and other enterovirus detection with real-time reverse transcription polymerase chain reaction (Real-time RT-PCR). The genotyping of non-EV71 and non-Cox A16 enteroviruses through sequencing partial VP1 coding gene were performed by RT-PCR. Full-length coding regions for the VP1 genes of EV71, Cox A16, Cox A6 and Cox A10 were amplified and sequenced to construct phylogenetic trees for phylogenetic analysis. Results Among the samples tested, 1063 were positive for enteroviruses (74.81%), including 222 EV71 positive samples, 340 Cox A16 positive samples, 8 EV71+Cox A16 positive samples and 493 non-EV71or non-Cox A16 enterovirus positive samples. Forty non-EV71 and non-Cox A16 enterovirus positive samples were selected randomly for further analysis by RT-PCR and sequencing, and among the 38 samples with definite results, 25 were Cox A6 positive (65.79%), 8 were Cox A10 positive(21.05%), 3 were Cox A4 positive (7.89%), 1 was Cox A5 positive (2.63%) and 1 was Cox A9 positive (2.63%). The phylogenetic analysis indicated that all the EV71 strains belonged to evolutionary branch C4a of gene subtype C4, and Cox A16 strains belonged to evolutionary branch B1a and B1b of gene subtypes B1. Phylogeneic analysis also indicated that Cox A6 and Cox A10 strains from Zhangzhou shared low homology with prototype strains and foreign strains but high homology with domestic strains. Conclusion Non-EV71 and non-Cox A16 enterovirus accounted for a high proportion in the pathogen spectrum of HFMD in Zhangzhou during 2013-2014. Five serotypes of non-EV71 and non-Cox A16 enteroviruses were successfully identified, and Cox A6 and Cox A10 were predominant. Phylogenetic analysis showed that EV71, Cox A16, Cox A6 and Cox A10 co-circulated and co-evolved with the strains detected both at home and abroad in Zhangzhou.