Epidemiological And Etoological Characteristics Of Hand, Foot-mouth Disease In Chongqing, 2014

Objective: To understand the epidemiological characteristic,pathogen distribution and the evolutionary change of hand-foot and mouth disease(HFMD) in Chongqing in 2015, and to provide a scientific basis for prevention, control and vaccine development of HFMD.Methods: Descriptive analysis was conducted to describe the epidemicological characteristics of all cases with hand-foot and mouth disease in Chongqing medical university affilited children’s hospital in 2015.The etiology of stool specimens collected from 432 HFMD cases were detected and analyzed by n RT-PCR, DNA sequencing, Homology comparision and constructing phylogenetic trees to make a systematic analysis of molecular biological characteristic with HFMD.Results:1.There were two peaks of the whole year for HFMD in Chongqing in 2015. The first peak occurred from April to July and the second peak occurred from October to December. The former accounted for 57.47% of the total number in annual cases respectively, while the later accounted for 30.81% respectively. Meanwhile,the number in male was more than that in female,and the incidence of male to female cases all the year round was 1.49 in Chongqing in 2015. Among all the cases, the number in male was more than that in female, most cases appeared at the children under 5 years age with the percentage 97%. Most patients were scattered?children and children in kindergarten.2. Among the 242 stool specimens, 210(86.78%) were detected with enterovrious infected, in which EV71 accounted for 58.10%(122/210),CA16 for 2.38%(5/210), CA6 for 2.86%(6/210), and other enteroviruses for 26.67%(56/210),and co-infection was 10%(21/210), while no single CA10 case occured.Infection overlap cases had three types, EV71 and CA16, EV71 and CA6, EV71 and CA10, which accounted for 0.48%(1/210)、9.05%( 19/210)、 0.48%( 1/210) of the whole posetive cases. The proportions of the mixed infection in the every enteroviruse were EV71 14.69%(21/143), CA16 16.67%(1/6), CA6 76.00%(19/25), CA10 100%(1/1). EV71 infected cases appeared every mouth,and the peak occured from April to October, while Coxsackievirus(most of them were CA6) cases in the summer had incerased more than that from October to December. EV71 infected cases appeared in different clinical types. In severe cases, EV71 was the predominant pathogen.Otherwise, the mild cases were caused by the EV71, coxsackievirus and other enteroviruses. EV71 cases appeared in all ages and the number increased as age growth under the 2 years old, while coxsackievirus、other enteroviruses and co-infection decreased.3. Phylogenetic analysis suggested that EV71 strains seperated from Chongqing in 2015 belonged to C4 a subtype, and CA16 was B1 b subtype. The gene sequences of CA6 strains in this study had a high homology with those strains from UK and the mainland of China. CA10 strains had the characteristic of geographic difference and showed a high homology with those strains from other part of mainland in China.Conclusions: The mordibidity of HFMD in Chongqing in 2015 related to the seasonal characteristics, and had an obvious difference in different genders. There were two morbidity peaks of the whole year for HFMD in Chong Qing in 2015, and the bigger one appeared from April to July. Among all the cases, the number in male was more than that in female,most cases appeared at the children under 5 years age with the percentage 97%. Most patients were scattered children and children in kindergarten.EV71 was the predominant pathogen in this area all the year round, while Coxsackievirus and other enteroviruses became the second major pathgen alternatly. A larger proportion of CA6 and CA10 co-infection occured in the whole overlapping infection cases.Discrepancy occured in different seasons and clinic types had a statistical significance.The morbidity peak of EV71 occured from April to October, while Coxsackievirus(most of them were CA6) cases in the summer had incerased more than that from October to December. EV71 was the predominant pathogen in severe cases. Otherwise, the mild cases were caused by the EV71, coxsackievirus and other enteroviruses. EV71 cases appeared in all ages and the number increased as age growth under the 2 years old, while coxsackievirus, other enteroviruses and co-infection decreased.Phylogenetic analysis suggested that EV71 strains seperated from Chongqing in 2015 belonged to C4 a subtype,and CA16 for B1 b subtype. The gene sequences of CA6 strains in this study had a high homology with those strains from UK and the mainland of China. CA10 strains had the characteristic of geographic difference and showed a high homology with those strains from other part of mainland in China.