Objective  To explore associations of serum iron (Fe), manganese (Mn), and molybdenum (Mo) with hand foot and mouth disease (HFMD) among children in Shenzhen city.

  Methods  We recruited 202 and 220 children diagnosed with severe and mild HFMD as cases and 208 healthy children having physical examinations as controls in in Shenzhen Municipal Children's Hospital between May 2013 and May 2015. We collected throat/anal swab specimens and blood samples of the children for pathogen detection with real-time quantitative polymerase chain reaction (qPCR) and determinations of serum Fe, Mn, and Mo with inductively coupled plasma mass spectrometry (ICP-MS).

  Results  The serum levels of Mn and Mo were significantly lower in mild cases (2.14 and 1.56 ug/kg) and severe cases (1.37 and 1.13 ug/kg) than those in the controls (3.52 and 1.72 ug/kg) (P < 0.05 for all); while there was no significant difference in serum Fe level among the three groups (P > 0.05). The serum Mn level was lower in the cases with Coxsackie virus 16 (CA16) and other viruses infection than that in the cases with enterovirus 71 (EV71) infection (P < 0.017) , but serum Mo and Fe levels did not differ significantly among the cases with different enterovirus infections (P > 0.05). No significant differences were observed in serum Mn and Mo levels among the cases of various age groups (P > 0.05). Spearman rank correlation analysis revealed a reverse correlation between serum Mn, serum Mo and HFMD severity (r_s = – 0.565, r_s = – 0.46; both P < 0.001). The results of logistic regression analysis demonstrated that high serum Mn and Mo levels were the protective factors against HFMD and with the increase of serum Mn and Mo, the risk of HFMD decreased in the children (odds ratio < 1, P < 0.05).

  Conclusion  The incidence of HFMD is related to the low levels of serum Mn and Mo among children.