[Epidemiological features and pathogenic characteristics of hand, foot and mouth disease in Gansu Province, China during 2008-2012].

This study aims to analyze the epidemiological features and pathogenic characteristics of hand, foot and mouth disease(HFMD)in Gansu Province,China and to provide a basis for the development of effective prevention and control measures.The descriptive epidemiological analysis was used to analyse the data of HFMD cases in Gansu.The specimens collected from hospitals were subjected to RT-PCR or realtime PCR to detect human enterovirus(HEV)nucleic acid,and HEV strains were isolated using human rhabdomyosarcoma cells and human laryngeal carcinoma cells.The complete VP1-encoding region of several identified enterovirus A71(EV71)and coxsackievirus A16(CVA16)was subjected to full-length amplification by RT-PCR and then to sequencing and analysis.A total of 52 550HFMD cases were reported in Gansu from 2008to 2012,including 205severe cases and 27deaths.The incidence rates in the whole province from 2008to 2012were 22.42/105,49.29/105,47.20/105,27.27/105,and 55.84/105,respectively. There were cases in all the 14cities or prefectures in Gansu,and Lanzhou had the largest number of cases(16 001cases),accounting for 30.45% of all cases in the province.HFMD cases were mostly reported during May to July,accounting for 51.69%of all cases throughout the year.The male-to-female ratio was 1.69:1.Of all the cases,87.59% were under the age of five.Of the 5 416cases for laboratory tests,3 322(61.34%)were positive for HEV nucleic acid,including EV71(46.96%),CVA16(41.57%),and other HEVs(11.47%).Among the 186severe cases,114(61.29%)were positive for HEV nucleic acid,and 82.46% of the positive cases for EV71.All the 25dead cases were infected with EV71.A total of 402 strains were isolated from 3 111specimens collected from hospitals(2 123throat swab specimens,705 stool specimens,and 705herpes specimens),including EV71(70.15%),CVA16(27.11),other coxsackievirus A(3.98%),coxsackievirus B(2.49%),echovirus(1.74%),and adenovirus(1.99%).The genotyping of VP1-encoding region showed that all the 194EV71strains isolated during 2008-2012belonged to the C4aevolutionary branch of C4subtype;among the 45CVA16strains,12belonged to the B1aevolutionary branch of B1subtype and 33to the B1bevolutionary branch,and B1bbecame the predominant subtype in 2012.In conclusion,in Gansu Province,HFMD occurs mostly in children under the age of five; EV71and CVA16are the main pathogens of this disease,and the two are predominant alternately from 2008to 2012;the severe and dead cases of HFMD are closely related to infection with EV71;the types of pathogens varied across different regions in the same year during 2008-2012.