Evaluate And Project Of The Burden Of Bacillary Dysentery Associated With Floods

BackgroundIncreasing evidence shows that an increase in frequency and intensity of various natural disasters was observed in the 20th century due to the changing climate.Flooding is one of the most severe and most common forms of natural disasters,accounting for up to one half of all natural hazards in the world.As the fifth reports of Intergovernmental Panel on Climate Change predicted,with the increasing higher sea levels and more server and frequent precipitation under future climatic variations,floods would increase in severity and frequency.Flooding is a major issue facing our country,which attracts great attention of the government and the public.Evaluating the influence of floods has become the main content for the international and domestic academics.China is a country with a vast territory and complicated climate types.Floods occurred with the characteristics of variety,widespread impact,uneven distribution of time and space and damages caused by floods are quite serious.As China is a country prone to a variety of natural disasters,flooding is the major meteorological disasters affecting many regions,which has raised barriers to the sustainable development of economy and society.In recent years,under the background of global climate change,the severity and frequent of floods may be increased and bring more disease burden to disaster areas.The deteriorated living condition,lacking of clean water and health service facilities would assist the transmission of infectious diseases.In recent years,many researchers have been studying the influence of floods on intestinal infection,especially its effects on bacillary dysentery.Resulted from Shigella bacteria,bacillary dysentery refers to a kind of bacterial infections in intestines causing serious diarrhea.This is still a main health issue all over the world,particularly in a few developing countries.Overall,the epidemiological review suggests that there is presently a weak evidence-base to assess the health impacts of flooding.Few studies have been conducted about the impact of rainstorm floods on human health,and most studies were only conducted in terms of one or several flood events with a lack of a longitudinal analysis.With the development of public health,infectious diseases are still a serious threat to the public health of China.In addition,it is possible that research using along time scale and large spatial scale data with the arrival of information age and the application of big data.So this study focuses on following three aspects:(1)to quantify the impact of floods on bacillary dysentery;(2)to estimate attributable burden of bacillary dysentery diseases due to floods;(3)to projected burden of disease for bacillary dysentery due to flood events.This study has important implications for public interventions and will provide scientific evidence in responding to floods related healthoutcomes.Objectives1.The study aimed to quantify the risks of various flood events on bacillary dysentery with adjustment meteorological factors,secular trend,seasonal effect and lag effect.2.The study aimed to evaluate the attributable burden of infectious diarrhea due to flood.3.The study aimed to project the excessive incidence of infectious diarrhea due to floods in the future period.MethodsHuaihua and Jishou city in Hunan province,Baise city in Guangxi Province were chosen as our study areas.Data about infectious diseases was obtained from the National Notifiable Disease Surveillance System.Flood data and meteorological data were obtained from the Yearbook of meteorological disasters and the China Meteorological Data Sharing Service System.Population data was obtained from the center of scientific data on public health.1.Assessment the relationship between the incidence of bacillary dysentery and various degrees of floods:Generalized additive mixed model and Spearman correlation were applied to analyze the relationship between monthly incidence of bacillary dysentery and 14 degrees of floods,then the relative risk and 95%confidence interval were calculated with adjustment the meteorological factors,secular trend,seasonal effect and lag effect.2.Assessment the attributable burden of bacillary dysentery due to floods:firstly,a 1:3 unidirectional case-crossover study was performed to determine the exposure period and control period.The multinomial logistic regression was conducted to evaluate the risk of floods on bacillary dysentery.Then the relative risk and 95%confidence interval were calculated from the model.Secondly,the method to estimate the years lived with disability(YLDs)as recommended by the WHO was used to assess the disease burden of the diseases.Thirdly,the potential impact fractions(PIFs)of bacillary dysentery were estimated based on the environmental framework of CRA developed by the WHO.The method of estimating attributable YLDs as recommended by the World Health Organization(WHO)was used to calculate burden of diseases during exposure effect-period of floods.3.Project the disease burden of bacillary dysentery due to floods in the future period:The Generalized additive model was used to evaluate the relationship between floods and bacillary dysentery;scenarios for floods in 2020,2030,2050 and 2100 was projected according to the meteorological data in the future period;The RRs of bacillary dysentery due to exposure of various flood events,the scenarios of future population growth?temperature and flood events were the basis for the projection.The ranges of increased disease burden for bacillary dysentery diseases in each scenario were projected.Results1.The results of spearman' s correlation analysis showed that the monthly incidence of bacillary dysentery was in a positive correlation with the moderate and severe floods,MCP,MAT,MARH and MCSD,with relevant lag times from 0 to 1 month.However,the flood duration and the MAWV were in a negative correlation with the incidence of bacillary dysentery,with a lag time of 0 and 1 month,respectively.After controlling for the other meteorological variables,monthly incidences of bacillary dysentery were in a positive correlation with the moderate floods(RR:1.40,95%Cl:1.16-1.69)and the severe floods(RR:1.78,95%CI:1.61-1.97).A negative correlation existed between the floods duration and the incidence of bacillary dysentery(RR:0.57,95%Cl:0.40-0.86).2.Floods significantly increased the number of cases in Jishou(ORs>1 from lag 0 to lag 4)and Huaihua(all ORs>1 on different lagged days).The strongest effect was observed at lag 1 days in Jishou(OR=3.537,95%CI:1.793-6.974),and lag 4 days in Huaihua(OR=2.217,95%CI:1.480-3.321),respectively.Multivariable analysis showed that the floods were significantly associated with an increased risk of bacillary dysentery after adjusting for other meteorological factors(OR=3.270,95%CI:1.299-8.228 in Jishou;OR= 2.212,95%CI:1.052-4.650 in Huaihua).The total YLD per 1000 in Jishou was significantly higher than that in Huaihua(0.0369 vs.0.0194).The YLD per 1000 of male in Jishou was higher than that of female(0.0226 vs.0.0143),while the same was the case in Huaihua(0.0114 vs.0.0080).The YLD per 1000 of bacillary dysentery in Huaihua was highest between the ages of 60 and 69 years(0.0310),following by the age of 70-79(0.0306).While the highest YLD per 1000 in Jishou was in children less than 4 years of age(0.0645),the second was in people aged 70-79(0.0522).The attributable YLDs and YLD per 1000 in Jishou(22.6438,0.0296)were significantly higher than those in Huaihua(11.8790,0.0157).3.The parameters of the GAMM showed that the morbidity of bacillary dysentery was significantly associated with floods(coefficients = 0.19,P<0.01)and temperature(coefficients = 0.08,P<0.01).After adjusting meteorological factors,the RR value for bacillary dysentery during flooded months was 1.21(95%CI:1.06-1.37).The GAMM also suggested that a 1? increase in temperature was related to an extra 8%(RR = 1.08,95%CI=1.03-1.14)incidence of bacillary dysentery.It can be observed that under the flood scenarios alone,the YLDs may increase by up to 4.0%(26)by 2020,2030,2050,and 8.0%(27)by 2100 under the emission scenario of RCP4.5 if other factors remain constant;And under the emission scenario of RCP8.5,the YLDs may increase by up to 4.0%(26)by 2020,2050,and 8.0%(27)by 2030,2100.With consideration of all scenarios,which include floods,temperature and population size,the YLDs for bacillary dysentery may increase by up to 16.0%(29)by 2020,24.0%(31)by 2030,20.0%(30)by 2050 and 8.0%(28)by 2100 compared to that in 2010 under the emission scenario of RCP4.5.And under the emission scenario of RCP8.5,the YLDs for bacillary dysentery may increase by up to 20.0%(30)by 2020,24.0%(31)by 2030,28.0%(32)by 2050 and36.0%(34)by 2100.Conclusions1.Floods exert a significant part in enhancing the risk of bacillary dysentery.Moreover,severe floods have a higher proportional contribution to the incidence of bacillary dysentery than moderate floods.2.A sudden and severe flooding with a shorter duration may cause more burdens of bacillary dysentery than a persistent and moderate flooding.3.The lagging effect exists on the impact of floods to bacillary dysentery.More attention should be paid to vulnerable groups,including younger children and elderly.4.Floods-related health burden of bacillary dysentery may increase in the future due to exposure to flood events if no effective intervention measures are taken.It has significant policy implications for adaptation and mitigation of future risks of climate change.Innovation1.Multiple flood events occurred in the study area to be analysis together based on the time series data.2.To quantify the relationship between various levels of floods and the incidence of bacillary dysentery,this study has,for the first time,adopted comprehensive measurement-YLDs,which can assist in evidence-based allocation of limited health resources,to estimate burden of disease among different subpopulations.3.With the background of global climate change,this analysis represents the first time to projected the YLDs of bacillary dysentery infection in 2020,2030,2050 and 2100 in Guangxi under the scenario of population growth?temperature change and flood events.Limitations1.There are other variables,such as the variability of the pathogen,the mobility of the population,socioeconomic status,changes in behavior and lifestyle and environmental hygiene that could impact the transmission of bacillary dysentery but could not be analyzed in this study.2.The limitation is in the projections of future scenarios,which has stated in the paper.3.Only two study areas(Guangxi and Hunan)were selected in the analysis.Moreover,the transmission of infectious diseases is very complicated.For having a better understanding of the health impact of floods,more studies conduct in other flood affected regions with different climate types,geographic locations,socio-economic condition,weather condition and ecological areas should be necessary.