The Epidemiological Characteristics Of Hand, Foot And Mouth Disease And The Association With Meteorological Factors In Minhang District, Shanghai

Background:Hand, foot and mouth disease (HFMD) is an acute infectious disease in human beings (especially children under 5) caused by multiple intestinal viruses and is featured with febrile illness and rash in the hand, foot and mouth. HFMD is highly contagious, and can be transmitted rapidly in various ways. This enables it to cause large scale epidemic in a short time and cause severe result which is hard to control. Nowadays the study of HFMD has made some progress but the mechanism of its transmission and influencing factors are still unclear. The vaccination and special treatment on HFMD have not been developed yet. The prevention and control of the disease still lacks pertinence. It is important to figure out the epidemic regulation to provide information in the prevention and control for HFMD.The global warming has important impacts on human living environment. With the development of people’s living standard and technology, the relationship between climate and disease has drawn more and more attention. It is reported that the Earth’s surface temperature will rise 1.1-6.4℃ by the end of 21st century; A Japanese researcher estimated that the incidence rate of HFMD will increase by 7%-14% with the global warming. In recent years, researches on the relationship between meteorological factors and HFMD from Japan, Singapore and Hong Kong indicated that meteorological factors can cause the incidence of HFMD to change. In China, similar researches are also undergoing in regions like Guangzhou and Shijiazhuang. Nowadays there are still less researches on the relationship of meteorological factors and HFMD using time series method. This study analyzed the association between meteorological factors change and the risk of HFMD was provided scientific basis for the prevention and early warning of HFMD.Objective:(1) To describe the epidemic status and epidemiological characteristics of HFMD in Minhang district, Shanghai during 2007-2011 and to provide scientific basis for health departments in making prevention & control strategies.(2) To analyze the changes in meteorological factors (temperature and humidity) and the risk of HFMD’s exposure-response relationship. To forecast the trend of HFMD epidemic and to provide scientific basis for establishing meteorological early warning system.Methods:(1) Rates and proportions were used in describing the epidemiological characteristics. Excel 2010 and PASW 18.0 were used to make data processing and statistical analysis.(2) Poisson regression based on generalized additive model was applied to time series regression model as well as to control such confounding factors as long-term trend, seasonal trend, week effect and precipitation. The exposure-response relationship of temperature/humidity and incidence of HFMD was firstly plot. Linear or nonlinear pattern was applied in the time series model depending on the curve shape. The average temperature in the previous week (lag 06) was taken as the exposure standard to estimate excess risk of temperature or humidity.(3) Holiday effect was controlled in this study. The temperature effect in 0、1、2、 3、4、5、6、7、8、9、10 days after the study day were calculated. Mgcv pack in R 3.0.2 was applied to fit the time series model.Result:Minhang district reported 17653 cases since 2007 to 2011,214 severe cases. The incidence rate and the mortality rate of severe HFMD showed a relatively low level.The incidence rate of HFMD in Minhang district showed a trend of rising year by year. The incidence in 2007 was 1303 persons and rose to 5645 persons in 2011. Average annual growth rate was 44.3%.The epidemic status of HFMD in Minhang district showed an obvious seasonality. Every residence or township had HFMD epidemic. They all showed a rising trend especially in residences. The ratio of male to female was 1.57:1. The patients were mainly composed by scattered or childcare children under 5 years old (93.18%). The incidence proportion of non-native population increased year by year since 2008. In year 2009-2011,66% of the patients were non-native.The risk of HFMD was associated with temperature/humidity under certain conditions. When the temperature was under 23℃the onset risk of HFMD increase 3.75%(95%CI:3.31%,4.20%) with each 1℃ increase in temperature. In an environment with higher humidity, the onset risk tended to increase. When relative humidity was increase, the onset risk of HFMD increase 1.07%(95%CI:0.63%,1.52%) with each 1 percent increase in relative humidity.Boys had a higher risk than girls under high temperature condition. Young children aged 0～3 years had the highest risk. When the temperature was under 23℃ the onset risk of HFMD of boy increase 3.73%(95%CI:3.28%,4.18%) with each 1℃ increase in temperature and the onset risk of HFMD of young children aged 0-3 years increase 3.73%(95%CI:3.30%,4.17%) with each 1℃increase in temperature.Temperature had a significant effect on the incidence of HFMD when holiday effect was controlled. Temperature effect was stable and showed significant relationship in different lag days. Week average temperature had the strongest association with the incidence of HFMD.Conclusion:In Minhang district HFMD is a common infectious disease with high morbidity and low mortality. Strengthen the prevention and control work of the non-native population. The most susceptible population was children under 5 years old. This indicated that emphasis should be laid on scattered or childcare children. Health education and management needed to be done carefully within children under 5 years old especially in non-native population.Meteorological factor had significant associations with the incidence of HFMD. Certain range of temperature and humidity were risk factor for the incidence of HFMD. It could be one of the indicators to forecast the incidence of HFMD. The result of this study indicated that it could be important to establish meteorological early warning system to reduce the harm caused by meteorological factors by means of surveillance, early warning and protection.