| BackgroundThe current climate warming is aggravating.Global climate change directly or indirectly affects the various aspects of the occurrence,transmission and development of infectious diseases,causing changes in pathogens and their carriers,transmission routes and the human body's immune status,thus affecting the trend of infectious diseases,posing a great threat to human health.The health effects of meteorological factors on the population have received widespread attention both at home and abroad,and most studies have shown that meteorological factors,especially temperature,humidity and rainfall are closely related with water-borne diseases.Other infectious diarrhea is a legal category C infectious disease in our country,which refers to infectious diarrhea other than cholera,bacterial and amebic dysentery,typhoid and paratyphoid.As other infectious diarrheas have many causes and lack of effective vaccination,it has been severely endangering human health.During periods of precipitation,especially heavy precipitation,local water quality is contaminated through a number of routes,including cross-contamination of wastewater carrying bacteria,protozoa and viruses and drinking water,runoff contaminating surface and groundwater,precipitation-induced puddles also provide a good living and breeding environment for mosquitoes and other pathogen carriers;heavy rain and floods help to transport causative pathogens rapidly into water supplies,these factors contribute to the outbreaks of water-borne infectious diseases.In addition,the temperature and humidity may directly affect the survival and reproduction of bacteria,also have an indirect impact on infectious diseases by changing human behavior.Previous studies have discussed more about the effects of severe rainfall events on the risk of diarrheal diseases,while studies on the relationship between low rainfall such as light rain and moderate rain and other infectious diarrhea is relatively rare;different rainfall levels were often divided by the percentile method(P90,P95 and P99 are commonly used),but this method is relatively crude and rough,which makes the guidance of our results limited.In addition,most studies focused on exploring the effects of extreme weather events(such as extreme precipitation,floods)or single meteorological factor(such as temperature)on infectious diseases,while no comprehensive reports on the relationship between meteorological factors and other infectious diarrhea have been reported.Based on this,my study used the monitoring data of infectious diseases and the meteorological data of the same period from 2005 to 2012,dividing daily rainfall into different grades by the division standard of the National Meteorological Administration,and established the quantitative model to calculate the effect of different rainfall levels on the incidence of other infectious diarrhea,then a stratified analysis was done to identify vulnerable groups;the relationship between average temperature,relative humidity and other infectious diseases were further comprehensively and systematically explored,so we can find the exposure-lag-risk associations and the health impacts of different effects,so as to provide a scientific basis for effective prevention and control of other infectious diarrhea.Objectives(1)Understanding the distributional characteristics of other infectious diarrhea on time,space and population;(2)Exploring the effects of different rainfall levels on other infectious diarrhea in the whole population;(3)Exploring the effects of different rainfall levels on other infectious diarrhea in different populations to find the vulnerable population;(4)Finding exposure-lag-risk associations between temperature,humidity and other infectious diarrhea;(5)Quantitatively exploring the relationship between extreme temperature,humidity and other infectious diarrhea.MethodsWe chose Chengdu city,Sichuan Province as research site.Other infectious diarrhea data from 2005 to 2012 were collected from the National Notifiable Disease Surveillance System;meteorological data of the same period were obtained from China Meteorological Data Sharing Service Network.Firstly,the descriptive analysis of the meteorological factors and other infectious diarrhea cases were carried out to obtain the distributional characteristics of the disease in time,space and population.Secondly,according to the precipitation grades division of China Meteorological Administration,within 24 hours,light rainfall is between 0.1-9.9mm,moderate rainfall is between 10-24.9mm,heavy rainfall is between 25-49.9mm,torrential rainfall is between 50-99.9mm and heavy torrential rainfall is between 100-249.9mm.Based on this,the generalized additive model was used to calculate the relative risk and 95%confidence interval of different rainfall levels on other infectious diarrhea,and then we established generalized additive models for quantitative analysis to identify vulnerable groups for different groups of people(by sex,age),respectively.Temperature and humidity were incorporated into the distributed lag nonlinear model in the form of cross-basis.After controlling for other meteorological factors,the long-term trend and seasonal effects,the exposure-lag-response relationship between two factors and disease were obtained.The daily average temperature,relative humidity of P1,P25,P75,P99 were defined as extremely cold,cold,hot,very hot,very dry,dry,wet,very wet,then quantitative analysis of the different effects on the incidence of other infectious diarrhea was done.Statistical description and statistical analysis were carried out by R 3.1.2,the spatial distribution was described by Arcgis 10.0.Results(1)Descriptive analysis:a total of 52 699 cases of other infectious diarrhea cases were found in Chengdu from 2005 to 2012,with a male-female ratio of 1.32:1;for age distribution,children under 4 years old accounted for the highest proportion(59.48%),while those over 65 years old accounted for the lowest proportion(5.89%);for occupation distribution,children accounted for the highest proportion(61.34%),whose main population was scattered children,while worker accounted for the lowest proportion(2.53%);the incidence of other infectious diarrhea had two peaks,the peak in summer was in June-September and in winter was in October-December,the time series distribution was consistent with that of meteorological factors.(2)Effects of different rainfall levels on the incidence of other infectious diarrhea:for the whole population,the greatest protection effect of light rainfall occurred at lag4,with a RR of 0.965(95%CI:0.944-0.986);there was no significant correlation between moderate rainfall and disease;the maximum hazard effect of heavy rainfall occurred at lagl,with a RR of 1.092(95%CI:1.028-1.159);the maximum protection effect of torrential rainfall was observed at lag21,with a RR of 0.882(95%CI:0.788-0.987);the maximum hazard effect of heavy torrential rainfall was observed at lag21,with a RR of 1.519(95%CI:1.228-1.879).(3)Analysis of vulnerable population:for light rain,women and 5-14-year-old children were vulnerable,the RRs were 1.034(95%CI:1.000-1.069)and 1.081(95%CI:1.003-1.165)separately;for moderate rain,women and 5-14-year-old children were vulnerable groups,with the RR of 1.069(95%CI:1.001-1.141)and 1.197(95%CI:1.047-1.369)respectively;for heavy rain,women and 5-14-year-old children were vulnerable groups,with RRs of 1.135(95%CI:1.141-1.614)and 1.357(95%CI:1.141-1.614)respectively;for torrential rain,the male and 0-4 year-old children were vulnerable,the RRs were 1.164(95%CI:1.018-1.332)and 1.154(95%CI:1.014-1.313)respectively;for heavy torrential rain,males and ?65 year-olds were vulnerable groups,with RRs of 1.622(95%CI:1.223-2.151)and 2.127(95%CI:1.034-4.376).(4)The relationship between temperature and humidity and other infectious diarrhea:the maximum hazard effect occurred when temperature was 29.90?,with a RR value of 3.21(95%CI:2.54-4.07);the maximum adverse effect was observed when relative humidity was 90.20%,with a RR value of 1.60(95%CI:1.40-1.82).(5)The effects of extreme temperature and humidity on the risk of other infectious diarrhea:the maximum cumulative effect of extremely cold,cold,hot and very hot effects appeared at lag0-2d,0-2d,0-7d and 0-21d,respectively,and the RRs were 0.67(95%CI:0.59-0.76),0.88(95%CI:0.82-0.94),1.20(95%CI:1.10-1.31),2.19(95%CI:1.85-2.59)respectively;the maximum cumulative effect of extremely dry,dry,wet and extremely moist effects appeared at 0-21d,0-2d,0-21d and 0-2d,respectively,and the RRs were 1.13(95%CI:0.89-1.44),0.98(95%CI:0.94-1.03),1.53(95%CI:1.38-1.70),0.96(95%CI:0.88-1.05)respectively.Conclusions(1)The effects of different rainfall on the incidence of other infectious diarrhea were different along lagged days,relevant departments should strengthen disease prevention and control measures after heavy rain and heavy torrential rain.(2)The protection of women and children aged 5-14 years after heavy rains,men and the elderly over 65 years old after heavy torrential rain should be strengthened.(3)The correlation between temperature,humidity and the incidence of other infectious diarrhea is nonlinear,when the temperature is 29.90? and the humidity is 90.20%,the biggest risk occurred.(4)The relevant department should pay attention to the prevention and control of other infectious diarrhea at lag0-7 after the emergence of heat effect,and at lag0-21 after the emergence of extreme heat effect and wet effect. |
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