[Study on the etiology of hand-foot-mouth disease outbreaks in Beijing in 2007].

OBJECTIVE: To identify the etiology of 8 human hand-foot-mouth disease (HFMD) outbreaks in Beijing, during May to July 2007.

METHODS: Reverse transcription-polymerase chain reaction (RT-PCR) method was used to directly type the specimens including fluid from the herpes and throat swabs from the HFMD patients. Using RD cell lines, the collected stool specimens were cultured followed by typing. Partial VP1 region of selected EV positive specimens and cultures were sequenced and both nucleic acid sequence and predicted amino acid sequence were analyzed.

RESULTS: The two HFMD outbreaks in Daxing region in Beijing in 2007 were caused by enterovirus 71 type (EV71), and the others were caused by Coxsackie virus A16 (Cox A16). Two EV71 strains caused epidemics in Daxing region in 2007 belonged to C4 subgenotype but on different branches in VP1 gene phylogenetic tree. The differences on nucleic acid sequence and amino acid sequence were 3.7% and 0.8% between the two EV71 stains, respectively. The Cox A16 strain in Shunyi region and the other strains were on different branches in phylogenetic tree, and the difference on nucleic acid and amino acid sequence were 3.7% and 0% respectively between the two Cox A16 stains.

CONCLUSION: The HFMD outbreaks occurred in Beijing in 2007 were caused mainly by EV71 and Cox A16, and there were two individual epidemic virus strains. Cox A16 seemed to spread more widely than EV71 in Beijing, 2007.