| Objective:Malaria is a tropical parasitic disease transmitted by mosquito vector.As one of the most serious public health problems,malaria poses a great threat to the lives of children,especially those living in sub-Saharan Africa.According to the latest malaria report published in November 2020,there are still nearly 87 countries in malaria endemic regions globally in 2019,with a total of 229 million malaria infection cases.In 2019,approximately 900 million malaria infection cases decreased compared with that in 2000.Looking at malaria deaths,we found that in the past 20years,they have dropped from 736000 to 409000.Moreover,malaria mortality among children under 5 years decreased from 84%to 67%.Despite the sharp decline in global malaria morbidity and mortality caused by intensive malaria interventions,the global burden of malaria-related diseases remains enormous.Current antimalarial measures mainly include the use of antimalarial drugs for prevention and treatment,and the use of long-lasting insecticide-treated mosquito nets and indoor residual spraying to prevent and control mosquitoes.However,more and more data show that this series of measures can not go too far.Therefore,in the face of such complex and serious mosquito-borne infectious diseases,we need to identify and support other effective measures to combat malaria.Good hygiene is universally considered one of the most efficacious and straightforward measures to prevent disease transmission.The most original and effective environmental management strategies are increasingly on the agenda as cross-sectoral collaborative approaches to malaria control and elimination are increasingly encouraged.With regard to our living environments,drinking water,sanitation and hygiene facilities have so far received little attention in the vast majority of African countries.Furthermore,even the prevention and control of these facilities and the spread of malaria and other neglected tropical diseases have not yet been widely used.Considering that the target date for both the malaria strategic map and the sustainable development goals to provide basic drinking water,latrines and other sanitation measures for communities,schools and health-care settings is 2030,we propose the assumption that redoubling efforts to upgrade and improve drinking water and sanitation as new initiatives to prevent and control malaria infection can accelerate the advance of the goal of total elimination of malaria by 2016-2030?In addition,indoor air pollution is known to be one of the leading causes of morbidity and mortality in developing countries.In high malaria transmission areas and regions,hemoglobin concentrations in almost all infants and many older children are reduced by malaria.Other studies have shown that smoke from biofuels can lead to anemia.Although developing countries are currently working to address the health impact of indoor air pollution caused by the use of biofuels in their homes through changing a range of practices,such as fuel types,stove technology and housing design,researches on association between cooking fuel use and malaria infection are rarely reported.In addition,studies on biofuel use and childhood malaria and anaemia have not been reported as well.In order to better propose environmental management strategies related to malaria infection,this study uses questionnaires on population and malaria infection in countries and regions across sub-Saharan Africa to describe and analyze the distribution of malaria cases at different altitudes and seasons.Model studies on exploring associations between types of drinking water and toilet use and malaria infection in children are conducted.By comparing the differences of malaria and anemia among children using clean fuels and biofuels,the management strategies of malaria-controlled living environment are defined,which provides a scientific basis for promoting the health of children in areas with high transmission and prevalence of malaria.Methods:1.Obtain questionnaires.Through reading a lot of literature,we found that DHS and MIS are large cross-sectional questionnaires designed for population health and malaria infection.By completing the complete experimental design,we successfully applied to the the DHS Program website for the questionnaire to the countries and regions across sub-Saharan Africa for subsequent analyses.2.Identify the studying areas and objects.Sub-saharan Africa have the highest child malaria mortality rates in the world.The age of the children involved in the study should be between 0 and 59 months.3.Quality control and data cleaning.In the seven stages of the DHS survey,these questionnaires were reviewed and modified at each part.At the end of the survey,quality control personnel reviewed the completed questionnaires.All questionnaires need to be carefully checked and double verified before they can be included in the study.Manually checking database samples and computer automatic sorting programs were used to identify the defects in the data set in order to achieve the purpose of"cleaning"data.4.Definition of outcome variables.For malaria infection,we used two methods to detect,namely microscopy and rapid diagnostic test.For malaria infection types,we divided into the following sorts,namely Plasmodium falciparum,Plasmodium vivax,Plasmodium ovale,Plasmodium malariae and others.In addition,the anemia status among malaria-positive children after altitude correction was selected as the outcome variable.The anemia statuses of severe,moderate and mild children were regarded as anemia among malaria-positive children.5.To explore the distribution of demographic and socio-economic indicators in different seasons and elevations.Use Student’t test or Mann-Whitney U test to detect age distribution differences.A Chi-square test or Fisher’s exact test was used to detect differences in the distribution of the two-category variables:sex,indoor residual sparying,house quality,cooking fuel,and household economic status.Use R*C checklist to detect differences in distribution of drinking water,toilet,mother’s highest level of education and use of mosquito nets.P<0.05 was considered statistically significant.6.To investigate the effects of seasons and altitudes on the prevalence of different types of malaria.Use a Chi-square test or Fisher’s exact test to detect differences and P<0.05 was regarded as a statistical difference.7.Explore the difference of malaria infection and anemia prevalence between urban and rural children.After stratified treatment according to the investigation season and altitude,the above differences were detected by a Chi-square test or Fisher”s exact test.All results were displayed with histograms.P<0.05 was regarded as a statistical difference.8.Groups of exposed and covariates.For the drinking water group,we mainly divided it into three categories,namely piped water,protected water and unprotected water.For the toilet group,we mainly divide it into three categories,namely flushtoilet,pit latrine toilet and no facilities.Cooking fuels were divided into clean fuels and biofuels.Clean fules include electricity and liquefied petroleum gas,whereas biofuels include kerosene,coal and lignite,charcoal,wood,straw/shrub/grass and crops.Cooking locations can be divided into indoor cooking and using separate rooms or outdoor cooking.Covariates mainly included the participant’s age,gender,indoor residual spraying during the last 12 months,use of insecticide-treated nets,housing quality,mother’s highest level of education and family wealth status.In addition,the nutritional status of children is divided into“stunt”and“non-stunt”.The indoor smoking frequency of family members can be divided into never smoking,less than one time per day and daily.9.To explore the impact of the use of different types of drinking water and sanitation on malaria infection in children in each country’s annual survey.The survey population was first divided into two groups,"poor"and"non-poor"children.Then,in each of these two groups,a logistic regression model was used for each year of the survey.The relationship between drinking water and toilet use and malaria infection were calculated for children aged 0-59 months and obtain a ORs.In this study,participants using protected water and pitlatrine toilet were used as reference groups,respectively.In these regression analyses,age,sex,indoor residual spraying in the last 12 months,insecticide-treated net use,housing quality,and mother’s highest level of education were adjusted.10.In this study,to determine the overall and the stratified a ORs for drinking water and sanitation and malaria risks among all the surveys,random-effect models in the meta-analysiss were used to pool logistic regression results for the surveys which were calculated among total children,“poor”children,and“nonpoor”children,respectively.Furthermore,to investigate the heterogeneity among the survey-specific effects,Tau-squared statistics,I~2 statistics and P-value were nalayized with chi-square and Cochran’s Q tests.11.To explore the use of cooking fuels and the risk of malaria in children,the distribution of different covariates in malaria positive and negative children was expressed as percentage(%),and the difference between the two groups was compared by Chi-square tests.According to the chi-square test results,the covariates of P<0.10 are left to the subsequent multivariate model.Based on a stratified analysis of household economic status and cooking location,a univariate logistic regression was preliminarily determined whether the use of biofuels increased the risk of malaria in children under5 years of age.After adjusting the covariates determined by the chi-square test results,a multivariate logistic regression was used to finally explore the relationship between the use of cooking fuel and the risk of malaria in children.P<0.05 was considered statistically significant.12.To investigate whether the use of biofuels exacerbates anemia in malaria-positive children.The distribution of anemia and non-anemia in malaria-positive children with different covariates was expressed as percentage(%),and the difference between the two groups was compared by chi-square tests.According to the chi-square test results,the covariates of P<0.10 are left to the subsequent multivariate model.A univariate logistic regression was used to determine whether the use of biofuels increases the risk of anemia in malaria-positive children under 5 years of age.When the covariates determined by the chi-square test results were adjusted,the relationship between the use of cooking fuel and anemia in malaria-positive children was determined by multivariate logisctic regression.P<0.05 was considered statistically significant.Results:1.The urban-rural differences of malaria prevalence(tested by microscopy or rapid diagnostic test)and anemia prevalence in different seasons and altitudes.2.The distribution of different malaria infection types in different seasons and altitudes is also different.Pre-rainy season infection rates of Plasmodium falciparum were higher than that in post-rainy season(Angola 2015-2016:10.11%vs 6.03%,P=0.018).Additionally,rainy season infection rates of Plasmodium falciparum were slightly lower than post-rainy season(Madagascar 2011:1.31%vs 4.36%,P<0.001).Infection rate of Plasmodium falciparum in middle altitude was higher than that in low altitude(Angola 2016-2016:13.11%vs 0.54%,P=0.006;Burundi 2011-2012:11.66%vs 4.37%,P<0.001;Cameroon 2011:25.49%vs 24.07%,P<0.001;Mali 2012-2013:67.65%vs 46.83%,P=0.001;Nigeria 2010:39.26%vs 35.32%,P=0.003).Plasmodium malariae infection rates in mid-altitude areas are also higher than that in high-altitude areas(Burundi 2011-2012:1.78%vs 0.38%,P<0.001).3.Overall,49 eligible surveys comprising data for 247440 individuals were included in the analysis.Of the included individuals,213920 children aged 0-59 months were tested for malaria infection using microscopy,with a prevalence of 18.8%,whereas59988(24.2%)positive cases were identified in 247440 children by rapid diagnostic test.Across all surveys,the average age of the children was 32.6 months,and 50.2%were male.4.Across all surveys,35.4%of the included children had access to unprotected water,followed by protected water(32.5%)and piped water(32.1%).Additionally,most children utilized pit latrine toilets(62.4%),followed by no facilities(26.8%)and flush toilets(10.8%).The proportion of households with a“poor”socioeconomic status was 48.6%overall.5.Across all surveys,both unprotected water and no facility users were associated with increased malaria risks(unprotected water:a OR 1.17,95%CI 1.07-1.27,P=0.001;no facilities:a OR 1.35,95%CI 1.24-1.47,P<0.001;respectively).,according to microscopy,wheras the odds of malaria infection were 48%and 49%less among piped water and flush toilet users,respectively(piped water:a OR 0.52,95%CI 0.45-0.59,P<0.001;flush toilets:a OR 0.51,95%CI 0.43-0.61,P<0.001).The trends of individuals diagnosed by rapid diagnostic test were consistent with those of individuals diagnosed by microscopy.6.Risk associations were more pronounced among children with a“nonpoor”socioeconomic status who were unprotected water or no facility users(unprotected water:a OR 1.21,95%CI 1.10-1.32,P<0.001;no facilities:a OR 1.46,95%CI 1.32-1.61,P<0.001).7.Compared with children who used biomass fuels as cooking fuels,the prevalence of malaria infections among clean fuel users was lower than that among biomass fuel users(8.82%vs 21.57%,P<0.001).8.The risk of malaria infections and malaria-related anemia among children under 5 years using clean fuels was significantly lower than that among children using biomass fuels,respectively[Malaria:OR(95%CI):0.35(0.30-0.41),P<0.001;Anemia:OR(95%CI):0.67(0.46-0.97),P=0.033].9.After adjusting confounding factors,the risk of malaria infections among the non poor children whose household cooked in the house and used clean fuels was reduced by 36%[OR(95%CI):0.64(0.43-0.95),P=0.027)].However,the use of clean fuels did not have a significant impact on anemia among malaria-infected children[OR(95%CI):0.90(0.53-1.52),P=0.681].Conclusion:1.There are urban-rural differences in malaria infections and anaemia among children under 5 years across sub-Saharan Africa.2.The distribution of different types of malaria infections among children under 5 years across sub-Saharan Africa varies widely in seasons and altitudes.3.Drinking water and sanitation are risk factors for malaria infections.Meanwhile,wealth levels play a confounding role in these relationships.4.Risk associations were more pronounced among children with a“nonpoor”socioeconomic status who were unprotected water or no facility users.Improved drinking water and sanitation conditions should be considered a potential intervention for the prevention of malaria in the long term.5.The use of clean fuels may reduce the risk of malaria among children under 5 years,especially in high malaria transmission areas. |
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