Analysis Of Dynamic Transmission Characteristics Of Hand, Foot And Mouth Disease In Chongqing

Hand-foot-mouth Disease(HFMD)is primarily caused by enterovirus 71 and coxsackieviruses A16,and usually transmitted among children under five years old.HFMD has been a significant public health challenge in China.In 2015,there were 1,767,931 cases and 114 deaths reported in China.To understand the transmission of the disease,we examined the age-specific force of infection(FOI)and the transmission rate of HFMD.Chongqing is the only municipality in the southwest part of China.It has the largest population density compared with other cities in the area,and it has a typical seasonality pattern of HFMD that was found in the southeastern part of China.The incidence of HFMD in Chongqing has two peaks,one in spring and one in winter;proportion of cases among children whose age under six years old were 93%,with the largest fraction of cases among 2-3 years old.The FOI of HFMD for Chongqing might be different between age groups,because we had an observation that the FOI of HFMD was identical among age groups before the 2008 outbreak,but was heterogeneity after the outbreak in Fuyang,Anhui provinceWe used catalytic model to estimate the age-specific FOI of HFMD for Chongqing,and used Time Series Susceptible Infectious Recovered(TSIR)model to estimate the time varied transmission rate of HFMD using data from May 2008 to December 2011.Our results show that: 1)the FOIs in different age groups were different,FOI of 3-4 years old age group was the highest,and FOI of 35-39 years old was relatively higher than that of other adults;2)The contact rate of HFMD in Chongqing is seasonal;3)Climatic factors have no effect on the change of transmission rate;transmission rate increased during summer and winter vocations,meaning that in China the transmission rate of HFMD in community was higher than the transmission rate in school.Control measures of HFMD should focus on young children,especially 3-4 years old,in community during summer and winter vocations.