Objective  To examine enterovirus infection rate and its influencing factors among close contacts of hand-foot and mouth disease ( HFMD) patients in Ningbo city and to provide evidences for HFMD prevention and control.

  Methods  We collected totally 1 097 feces and throat/anal swab specimens from 366 close contacts of HFMD patients in Cixi and Yuyao prefecture and Fenghua distirct of Ningbo municipality during the period from January 2016 to December 2017. Enterovirus nucleic acid was detected for all the specimens.

  Results  Of all the specimens, 207 were positive for enterovirus nucleic acid, with a detection rate of 18.87%. The number of positive specimens (detection rate) were 29 (2.64%), 56 (5.10%), and 122 (11.12%) for enterovirus A71 (EV-A71), Coxsackie virus A16 (CV-A16), and the other enterovirus, respectively. Multivariate unconditional logistic regression analysis indicated that anal and throat swab specimens were less likely to be enterovirus positive compared to feces specimens and specimens collected during epidemic season from April to July in a year were more likely to be enterovirus positive in comparison with the specimens collected in other seasons.

  Conclusion  The enterovirus detection rate is high and mainly influenced by type of the specimens collected, the time of specimen sampling and detection result of other pathogens among close contacts of HFMD patients in Ningbo city.