Abstract
Background: Amid numerous outbreaks of hand, foot and mouth disease (HFMD) in Asia over the past decade, studies on
spatio-temporal clustering are limited. Without this information the distribution of severe cases assumed to be sporadic. We
analyzed surveillance data with onset dates between 1 May 2008 to 31 October 2013 with the aim to document the spatiotemporal
clustering of HFMD cases and severe cases at the county level.
Methods: Purely temporal and purely spatial descriptive analyses were done. These were followed by a space-time scan
statistic for the whole study period and by year to detect the high risk clusters based on a discrete Poisson model.
Results: The annual incidence rate of HFMD in Guangxi increased whereas the severe cases peaked in 2010 and 2012. EV71
and CoxA16 were alternating viruses. Both HFMD cases and severe cases had a seasonal peak in April to July. The spatiotemporal
cluster of HFMD cases were mainly detected in the northeastern, central and southwestern regions, among which
three clusters were observed in Nanning, Liuzhou, Guilin city and their neighbouring areas lasting from 1.2 to 2.5 years. The
clusters of severe cases were less consistent in location and included around 40–70% of all severe cases in each year.
Conclusions: Both HFMD cases and severe cases occur in spatio-temporal clusters. The continuous epidemic in Nanning,
Liuzhou, Guilin cities and their neighbouring areas and the clusters of severe cases indicate the need for further intensive
surveillance.