A severe case of co-infection with Enterovirus 71 and vaccine-derived Poliovirus type II.

Enterovirus 71 (EV71) is often identified as the primary pathogen that directly leads to severe cases of HFMD, whereas the association between other enteroviruses and EV71 infection remains largely unclear. Here we report a rare case of a 5-year-old boy co-infected with EV71 and vaccine-derived Poliovirus (VDPV) type II, which were identified based on PCR and sequence analysis results and clinical symptoms and were characterized on CT. We determined that the EV71 strain belongs to the C4 subtype, and the VDPV II strain was closely genetically related to the reference Sabin type II strain. This report may improved our understanding of the clinical significance of the associations between clinical signs and the infectious properties of the involved pathogens.