Severe hand, foot and mouth disease associated with Coxsackievirus A10 infections in Xiamen, China in 2015

Background: Coxsackievirus A10 (CV-A10) is one of the etiological agents associated with hand, foot and mouth disease (HFMD) and usually causes mild cases. During 2009-2014, no severe cases caused by CV-A10 was reported in Xiamen, China, however, an increase in cases was seen in 2015. Objectives: We aimed to perform a retrospective molecular epidemiological analysis of HFMD associated with CV-A10 infections in Xiamen. Study design: CV-A10 VP1 (n = 41) capsid and full-length or near full-length genomes (n = 14) were sequenced. Phylogenetic trees were constructed based on these sequences and other reference sequences and nucleotide and amino acid changes were characterized. Results: From 2009-2014, no laboratory-confirmed CV-A10 infections associated with severe cases were identified, however, in 2015, 39% (7/18) of severe HFMD cases were CV-A10 infections. Sequence analysis of severe and non-severe CV-A10 HFMD cases determined that severe cases predominantly clustered with an emerging clade E lineage A strain which contained 4 nucleotide changes in 5' UTR and 5 amino acid substitutions in structural and non-structural proteins. Conclusions: The results indicate CV-A10 infection may be emerging as a new and major cause of severe HFMD and CV-A10 surveillance should be increased and considered in HFMD prevention and control strategies.