Characteristics of high incidence of hand foot and mouth disease and related factors in autumn of 2017 in Guangdong

Objective To understand the factors associated with the abnormal increase of hand food and mouth disease (HFMD) cases in autumn of 2017 in Guangdong province and provide scientific evidence for HFMD prevention and control. Methods The information about HFMD cases and outbreaks were collected through National Disease Reporting Information System. The stool samples and anal swab samples were collected weekly from HFMD sentinel hospitals in Guangdong for real time RT-PCR or RT-PCR to detect enterovirus nucleic acid. The positive samples of Cox A6 nucleic acid were selected for full length sequence amplification to find out the amino acid changes of gene loci. Microsoft Office Excel was used for data entry and SPSS16.0 was used for statistical analysis. Results A total of 152 791 HFMD cases were reported from 1 September to 31 October in 2017, an increase of 133.25% compared with the same period during 2011-2016 and an increase of 23.16% compared with summer in 2017. During the incidence peak in this autumn, 24 822 cases occurred per week, an increase of 34.72% compared with summer peak in 2017 and an increase of 167.71% compared with the incidence peaks during the same period from 2011 to 2016. The incidence intensity (calculated according to weekly incidence) increased in 20 prefectures except Zhanjiang and the increases of 100.00% were observed in 9 prefectures, including Yunfu and Maoming. The incidences in all age groups were higher than those during the same period from 2013 to 2016. Most cases were children outside child care settings. The sentinel surveillance indicated that the positive rate of Cox A6 from September to October was 80%. The nucleotide homology of Cox A6 virus in 2017 was 97.3%, which reduced comparing with the result of 2015 and 2016. Conclusion There was an abnormal growth of HFMD incidence in Guangdong in autumn of 2017. This study indicated that the high incidence was associated with the predominant strain shift to Cox A6, resulting in overall increase of HFMD incidence in Guangdong.