Spatial Clustering of Severe Hand-Foot-Mouth Disease Cases on Hainan Island, China.

The incidence of severe hand-foot-mouth disease (HFMD) in Southeast and East Asia has increased in recent years. This study explored spatial clusters of the incidence and proportion of severe HFMD cases on Hainan Island, where the prevalence and mortality of HFMD were the highest in China during 2011. A spatial autocorrelation statistic (Anselin's Local Moran I) was calculated for the Empirical Bayesian (EB)-smoothed dataset of severe HFMD cases. Significant spatial clusters were detected for both the incidence and proportion of severe HFMD cases. Population density was higher in spatial clusters with a high proportion of severe HFMD cases among total HFMD cases. We speculate that a higher proportion of severe HFMD cases were diagnosed in densely populated townships. This should be considered when analyzing the HFMD database of Hainan Island.