| BackgroundBacillary dysentery(BD),caused by a group of Shigella bacteria,is a gastrointestinal infectious disease that can lead to severe infections and delayed treatment may result in hemolytic uremic syndrome and even death.The disease is primarily prevalent in developing countries and ranks high among class A and B notifiable infectious diseases in China,imposing significant economic and social burdens.Epidemiological studies have revealed a certain correlation between the incidence of bacillary dysentery and meteorological factors.Current research on the impact of meteorological factors such as temperature and precipitation on the occurrence of bacillary dysentery,both domestically and internationally,has mostly employed methods such as lagged distributed non-linear models or Bayesian spatiotemporal models.However,these studies have relatively short durations and have been focused on specific provinces in China,with limited utilization of long-term monitoring data to analyze the influence of environmental factors on the nationwide incidence of bacillary dysentery.ObjectiveThe present study aims to investigate the association between temperature,precipitation,and the incidence of bacillary dysentery using a multi-period doubly differenced model based on the generalized additive model framework.This research seeks to explore the exposure-response relationship between bacillary dysentery and temperature and precipitation,identify vulnerable populations and regions at attributed risk,and provide valuable insights for the development of effective prevention and control strategies during outbreaks of bacillary dysentery.Method1.Multi-dimensional,multi-scale data collection and compilation were conducted in this study.Meteorological monitoring data(including temperature,precipitation,and relative humidity)from 31 provinces in China spanning the years 2005 to 2018 were collected.Additionally,monthly incidence data of bacillary dysentery,socio-economic data(such as per capita GDP),and urban population data were gathered.2.This study employs visualization tools to explore the spatiotemporal variation characteristics of temperature,precipitation,and the incidence of bacillary dysentery nationwide.3.Based on the generalized additive model,this study developed a multi-period doubly differenced(DID)design model to investigate the exposure-response relationship between BD incidence and environmental temperature and cumulative precipitation,and quantify the risks of BD incidence associated with environmental temperature and cumulative precipitation.4.This study conducted a stratified analysis to identify the risk attribution of environmental temperature and precipitation exposure on BD incidence among different age groups,seasons,regions,and GDP levels.This study also identified vulnerable populations and regions.Results1.Basic information: A total of approximately 3.33 million cases of bacillary dysentery were included from 31 provinces and regions in Chinese mainland from 2005 to 2018.Among them,the number of cases in the age groups of 15-60 years old and 0-5 years old were 1,439,315 and 1,076,857,respectively,accounting for 43.2% and 32.3% of the total cases.The average temperature,standard deviation of average temperature,mean cumulative precipitation,and mean relative humidity in the provinces and regions of China were 13.3℃,9.4℃,809.02 mm and 66.0%,respectively.2.Spatial and temporal distribution patterns were observed in this study.Over the 14-year period,the spatial distribution maps of annual average temperature and cumulative precipitation in China exhibited an increasing trend from north to south.Provinces with higher incidences of cumulative bacillary dysentery were concentrated in the central region,particularly Beijing,Hebei,Henan,and Sichuan provinces.The monthly incidence of bacillary dysentery nationwide showed consistent temporal variations with temperature and precipitation,reaching peak levels during the warm season(May to October)and reaching the lowest levels during the cold season(January to April,November to December).Analysis using the generalized additive model revealed that the five provinces with the highest correlation between temperature and precipitation exposure were Tianjin,Chongqing,Anhui,Henan,and Xinjiang Uygur Autonomous Region,with deviation interpretability ranging from 71.4% to 84.3%.Furthermore,the five provinces with the lowest correlation in temperature exposure were identified as Hainan,Guizhou,Fujian,Guangxi Zhuang Autonomous Region,and Zhejiang provinces,while the five provinces with the lowest correlation in precipitation exposure were Hainan,Guizhou,Fujian,Zhejiang,and Guangdong provinces.Notably,all these provinces are concentrated in the southern region.3.Effect of temperature on the risk of Bacillary Dysentery: Elevated ambient temperature increases the risk of BD.For every 1℃ increase in the annual average temperature,the excess risk of BD increases by 70.29%.The positive correlation is more pronounced in the warmer months than in the colder months.People aged 5 to 15 are more likely to be infected with BD than other groups,and the excess risk is as high as 720.43%(95%CI:635.95%,814.62%),that is,when the annual average temperature rises by 1℃,the risk of bacillary dysentery will increase 7.2 times,followed by people aged 15 to 60,whose ER value was 124.10%(95% CI: 112.66%,136.16%).The northern regions of China have a higher risk of BD than the southern regions,while areas with different levels of economic development have similar risks of BD.4.The impact of precipitation on the risk of bacillary dysentery incidence is as follows:There exists a "U"-shaped relationship between precipitation and the risk of bacillary dysentery,indicating the presence of a threshold effect.In the analysis stratified by population,region,and economic level,both increases and decreases in precipitation could contribute to the occurrence of bacillary dysentery outbreaks.Increased precipitation is associated with a higher risk of bacillary dysentery in economically developed regions,while economically disadvantaged regions show a negative excess risk.Overall,changes in precipitation have the greatest impact on children under the age of 5.However,during the warm season(May to October),individuals aged 15 and above are more susceptible to the influence of precipitation on the risk of bacillary dysentery incidence,while the opposite trend is observed during the cold season.ConclusionThe study revealed that as environmental temperature increases,the risk of bacillary dysentery incidence gradually rises.The relationship between precipitation and the risk of bacillary dysentery incidence generally follows a "U"-shaped pattern,indicating the presence of a threshold effect.Among various age groups,individuals aged 5 to 15 and 0 to5 are more susceptible to bacillary dysentery infection under changing temperature and precipitation conditions.These findings suggest the need for effective prevention and control strategies,particularly during seasons of rising environmental temperatures,especially in areas characterized by high population density due to economic development and low precipitation.Enhancing protection measures for vulnerable populations is crucial in order to prevent outbreaks and control the spread of bacillary dysentery. |
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