An Empirical Study On Epidemiological Features And Influencing Factors Of HFMD

Hand-foot-mouth disease(HFMD)is a frequently occurring epidemic and has be-coming an important cause of childhood mortality in China.Considering its significant impact nationwide,the surveillance data of HFMD in Fuyang was selected as a sample.The epidemiological characters of HFMD and its influencing factors were studied in this paper,including risk factors for severe HFMD cases and the effect of meteorological factors.A total of 95 937 HFMD cases were reported in Fuyang from 2009 to 2013,in-cluding 95 417 common cases and 520 severe cases.Descriptive methods were used to analyze the time,spatial,population,virus serotype,age in month,birth month and onset month distribution of HFMD.We found that HFMD cases peaked every year in April-June.The occurrence of HFMD was highest in Yingshang and Linquan,the in-cidence rate was highest in Yingzhou while most severe cases were reported in Taihe.Among reported cases,63.61%were male and 36.39%were female and the average male-to-female ratio was 1.75:1.Children living at home predominated reported cases(96.8%).Of 1 000 laboratory confirmed cases,enterovirus 71(EV 71),coxsackie A16(Cox A16)and other enterovirus accounted for 59%,7.2%and 33.8%respectively.The onset of HFMD is age-dependent and exhibits a 12-month periodicity,with 12-,24-,36-,48 and 60-month-old children being the most frequently affected groups.For children under 60 months old,children born in May had 8-fold elevated risk(relative risk = 8.88,RR)for severe HFMD compared with January-born children.We examined the risk factors for severe HFMD case by Logistic regression model.From the univariate analysis we found that patients age,residence,birth month as well as the seven-day averaged temperature,maximum temperature and minimum temperature before the date of onset were the risk factors.In the multivariate regression model,living in Taihe and Yingshang were associated with severe HFMD(the odds ratio was 2.68 and 1.99 respectively,OR),while living in Yingzhou was the protective factor(OR = 0.56),when the reference group was living in Linquan.Patients born in March-December were 2 times more at risk for severe HFMD compared with patients born in January.Patients born in August had a five-fold higher risk of severe HFMD than January-born patients.Young patients were associated with HFMD severity,patients who experi-enced higher seven-day averaged temperature before onset had more risks for severe HFMD(OR?1.02).We investigated the relationship between climate factors and HFMD cases with generalized additive models.After adjusting for time trend and seasonality,we found that average temperature and relative humidity were weekly associated with HFMD cases.Under the assumption of climate factors' linear effect,every 1? increase in temperature was associated with 2.79%more risk of HFMD cases.Simultaneously,one 1%increase of relative humidity could decrease HFMD risk by 0.32%.Under the non-linear effect,we found that average temperature and relative humidity were risk factors for HFMD when the temperature was above 13? and relative humidity was higher than 70%.When making management policies,government agencies could take into account the identified patterns to optimize interventions.For example,targeted vaccination strategies for high risk groups may help increase the vaccination efficiency.Results in current study could also assist in providing early warning for the society at appropri-ate time.