Changing epidemiology of hand, foot, and mouth disease in Hong Kong, 2001-2009

We report the surveillance findings of hand, foot, and mouth disease (HFMD) collected from a general practitioner-based sentinel surveillance system and outbreaks reported by institutions and a laboratory-based enterovirus surveillance system in Hong Kong from 2001 to 2009. A seasonal peak was detected in the warmer months (May-July), along with a smaller winter peak (October-December) from 2006 onwards. The number of older children (>5 years) infected increased from 25.4% in 2001 to 33.0% in 2009 (P=0.01, Mantel-Haenszel chi-square test). Laboratory surveillance detected a cyclical high enterovirus 71 activity every 3 to 4 years. This activity was associated with a higher average hospitalization rate for HFMD patients in the outbreaks reported in the corresponding year, although the difference was only marginally significant (P=0.09, linear regression test). The changing epidemiology of HFMD warrants continuous surveillance in order to guide preventive public-health actions.