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

Objective:To analyze the epidemiological and etiological characteristics of hand-foot-mouth disease (HFMD) in Chongqing in 2014, and to provide a basis for prevention and control of HFMD.Methods:A descriptive analysis was conducted to describe the epidemic characteristics of hand-foot-mouth disease cases in Chongqing children’s hospital in 2014. Stool samples was collected from 432 HFMD cases, To detect and analyze the etiological agents involved in HFMD by nRT-PCR, DNA sequencing and constructing phylogenetic trees.Results:1. The ratio of male to female cases was 1.44 in Chongqing in 2014, most cases were scattered children and children in kindergarten, and they accounted for 97.81%. And 93.91% of the cases were under 5 years old. There were two distinct peaks of HFMD the whole year, the first peak occurred from April to July and the second peak occurred from September to December, accounting for 36.16% and 53.49% of the total number in annual cases respectively.2. Among the 432 stool samples,364 (84.26%) were infected with enterovrious, including EV71 (53.57%,195/364), CA16(4.95%,18/364), CA6(6.32%,23/364), CA10(1.65%,6/364), other enteroviruses (21.15%, 77/364), co-infection (12.36%,45/364). The peak of detection rate of EV71 appeared during April to July, while coxsackievirus (most of them were CA6) appeared during September to December. In severe cases, EV71 was the predominant causative agent which accounted for 64.44%. In mild cases, EV71, coxsackievirus and other enteroviruses were the main causative agent. EV71 appeared in all ages and the percentage increased as age increased, while coxsackievirus, other enteroviruses and co-infection decreased.3. Sequence analysis showed that EV71 strains belonged to subtype C4a and CA16 belonged to subtype B1b. The sequences of CA6 strains in this study had a high homology with those strains from Japan and Spain. The genetic characteristics of CA10 strains displayed geographic difference and showed a high homology with those strains from other part of China.Conclusions:The epidemiological characteristics of HFMD in Chongqing in 2014 have a relationship with gender, population and season distribution. The number of male cases was larger than that of female cases. The majority of cases were scattered children and children in kindergarten, with the highest morbidity in children aged< 5 years. There are two distinct peaks of HFMD the whole year, the first peak occurred from April to July and the second big peak occurred from September to December. EV71 is the principal pathogen of HFMD. The composition of the pathogens was difference in age, season and clinical type. The percentage of EV71 increased as age increased, while coxsackievirus, other enteroviruses and co-infection decreased. The peak of EV71 appeared during April to July, while coxsackievirus (most of them were CA6) appeared during September to December. In severe cases, EV71 was the main causative agent. In mild cases, EV71, coxsackievirus and other enteroviruses were the main causative agent. Sequence analysis showed that EV71 strains belonged to subtype C4a and CA16 belonged to subtype Blb.The sequences of CA6 strains in this study had a high homology with those strains from Japan and Spain. The genetic characteristics of the CA10 strains displayed geographic differences and showed a high homology with those strains from other part of China.