Epidemiology of hand, foot, and mouth disease and genotype characterization of Enterovirus 71 in Jiangsu, China.

BACKGROUND: In the spring of 2008, an EV71-caused hand, foot, and mouth disease (HFMD) outbreak occurred in Fuyang city, Anhui Province, China. Jiangsu Province that borders Auhui to the east is presumed as a key station for the spread of EV71 to other regions of the Yangtze River Delta.

OBJECTIVES: To investigate the HFMD prevalence in Zhenjiang city of Jiangsu from May 2008 to October 2009, and the epidemic origin of EV71 circulating in Jiangsu.

STUDY DESIGN: During May 2008 and October 2009, a total of 6324 HFMD cases in Zhenjiang, Jiangsu, were investigated. Sixty throat specimens were randomly selected from different patients, and 28 nucleotide sequences of EV71 VP1 regions were successfully determined by RT-nested-PCR and sequencing. EV71 genotypes were characterized by phylogenetic analyses.

RESULTS: The incidence rate of HFMD was highest in the period of March-July and in the 1-4 years old age groups. Intriguingly, there was a slight predominance for boys and for children living in rural areas in HFMD infection. Phylogenetic analyses indicated that all Jiangsu EV71 strains and most China strains belonged to subgenotype C4a.

CONCLUSION: The C4a was the most prominent EV71 subgenotype circulating in China. Routine HFMD surveillance should be focused on the period of March-July, and more prevention efforts should be aimed at 1-4 years old children. Moreover, government efforts are urgently needed to improve public health condition and medical service quality in rural areas.