Piped water supply interruptions and acute diarrhea among under-five children in Addis Ababa

19 Pages·2017·1.97 MB·English

RESEARCHARTICLE
Piped water supply interruptions and acute
diarrhea among under-five children in Addis
Ababa slums, Ethiopia: A matched case-
control study
MetadelAdane1*,BezatuMengistie2,GirmayMedhin3,HelmutKloos4,WorkuMulat5
1 EthiopianInstituteofWaterResources(EIWR),AddisAbabaUniversity,AddisAbaba,Ethiopia,2 College
ofHealthandMedicalSciences,HaramayaUniversity,Haramaya,Ethiopia,3 AkliluLemmaInstituteof
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Pathobiology,AddisAbabaUniversity,AddisAbaba,Ethiopia,4 DepartmentofEpidemiologyand
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Biostatistics,UniversityofCalifornia,SanFrancisco,California,UnitedStatesofAmerica,5 Departmentof
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CivilandEnvironmentalEngineering,UniversityofConnecticut,Storrs,CT,UnitedStatesofAmerica
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a1111111111 *[email protected]
Abstract
OPENACCESS
Citation:AdaneM,MengistieB,MedhinG,Kloos Background
H,MulatW(2017)Pipedwatersupply
interruptionsandacutediarrheaamongunder-five Theproblemofintermittentpipedwatersuppliesthatexistsinlow-andmiddle-incomecoun-
childreninAddisAbabaslums,Ethiopia:A triesisparticularlysevereintheslumsofsub-SaharanAfrica.However,littleisknownabout
matchedcase-controlstudy.PLoSONE12(7):
whetherthereisdeteriorationofthemicrobiologicalqualityoftheintermittentpipedwater
e0181516.https://doi.org/10.1371/journal.
supplyatahouseholdlevelandwhetheritisafactorinreducingorincreasingtheoccur-
pone.0181516
renceofacutediarrheaamongunder-fivechildreninslumsofAddisAbaba.Thisstudy
Editor:PhilipC.Hill,UniversityofOtago,NEW
aimedtodeterminetheassociationofintermittentpipedwatersuppliesandpoint-of-use
ZEALAND
(POU)contaminationofhouseholdstoredwaterbyEscherichiacoli(E.coli)withacutediar-
Received:June1,2016
rheaamongunder-fivechildreninslumsofAddisAbaba.
Accepted:July3,2017
Published:July19,2017 Methods
Copyright:Thisisanopenaccessarticle,freeofall Acommunity-basedmatchedcase-controlstudywasconductedfromNovembertoDecem-
copyright,andmaybefreelyreproduced,
ber,2014.Casesweredefinedasunder-fivechildrenwithacutediarrheaduringthetwo
distributed,transmitted,modified,builtupon,or
otherwiseusedbyanyoneforanylawfulpurpose. weeksbeforethesurvey.Controlswerematchedbyageandneighborhoodwithcasesby
TheworkismadeavailableundertheCreative individualmatching.Datawerecollectedusingapre-testedstructuredquestionnaireandE.
CommonsCC0publicdomaindedication.
colianalysisofwaterfrompipedwatersuppliesandhouseholdstoredwater.Afive-tube
DataAvailabilityStatement:Allrelevantdataare methodofMostProbableNumber(MPN)/100mlstandardprocedurewasusedforE.coli
withinthepaperanditssupportinginformationfile.
analysis.Multivariableconditionallogisticregressionwith95%confidenceinterval(CI)was
Funding:EthiopianInstituteofWaterResourcesof usedfordataanalysisbycontrollingpotentialconfoundingeffectsofselectedsocio-demo-
AddisAbabaUniversityandWolloUniversity
graphiccharacteristics.
fundedthisresearchproject.AddisAbabaWater
andSewerageAuthorityalsosupportedthe
researchbymakingavailablefreeofchargeallthe Mainfindings
necessaryreagentsandchemicalsfor
Duringthetwoweeksbeforethesurvey,87.9%ofcasehouseholdsand51.0%ofcontrol
bacteriologicalanalysisofwater.Thefundershad
noroleinstudydesign,datacollectionand householdshadanintermittentpipedwatersupplyforanaverageof4.3daysand3.9days,
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Pipedwatersupplyinterruptionsandacutediarrhea
analysis,decisiontopublish,interpretationofthe respectively.POUcontaminationofhouseholdstoredwaterbyE.coliwasfoundin83.3%of
dataorpreparationofthemanuscriptfor thecasehouseholds,and52.1%ofthecontrolhouseholds.Inafullyadjustedmodel,aperi-
publication.
odicallyintermittentpipedwatersupply(adjustedmatchedoddsratio(adjustedmOR)=4.8;
Competinginterests:Theauthorshavedeclared 95%CI:1.3–17.8),POUwatercontaminationinhouseholdstoredwaterbyE.coli(adjusted
thatnocompetinginterestsexist.
mOR=3.3;95%CI:1.1–10.1),waterretrievedfromwaterstoragecontainersusinghandle-
Abbreviations:AdjustedmOR,Adjustedmatched lessvessels(adjustedmOR=16.3;95%CI:4.4–60.1),andwaterretrievedbyinterchange-
oddsratio;UnadjustedmOR,Unadjustedmatched
ablyusingvesselsbothwithandwithouthandle(adjustedmOR=5.4;95%CI:1.1–29.1)
oddsratio;CI,Confidenceinterval;E.coli,
Escherichiacoli;l/c/d,literpercapitaperday;MPN, wereindependentlyassociatedwithacutediarrhea.
MostProbableNumber;POU,Point-of-Use;$US,
UnitedStatesDollars;WHO,WorldHealth
Conclusion
Organization.
Weconcludethatprovisionofcontinuouslyavailablepipedwatersuppliesandeducationof
caregiversaboutproperwaterretrievalmethodsofhouseholdstoredwatercaneffectively
reducePOUcontaminationofwateratthehouseholdlevelandtherebyreduceacutediar-
rheaamongunder-fivechildreninslumsofAddisAbaba.Promotionofhouseholdwater
treatmentisalsohighlyencourageduntiltheCity’swaterauthorityisabletodelivercontinu-
ouslyavailablepipedwatersupplies.
Introduction
Onehundredforty-sevencountries,includingEthiopia,metthe2015MillenniumDevelop-
menttargetofprovidingdrinkingwaterfromimprovedsources[1].However,arecentstudy
indicatedthatpoliciesbasedonmonitoringofprogresstowardMillenniumDevelopment
Goals(MDGs)andongoingSustainableDevelopmentGoals(SDGs)failedtoconsiderthe
rangeofchallengesthathaveyettobesolvedinordertomeetpeople’swaterandsanitation
needs,andthereforegiveaninflatedsenseofprogress[2].Althoughseveralstudieshavedocu-
mentedthatwaterfromimprovedsourcesreducedtheoccurrenceofdiarrheaamongunder-
fivechildren[3–5],lessinformationisknownaboutthesafety[6]andmicrobialqualityof
water[6,7].Thisdiscrepancyisinlargeextentduetotheintermittentnatureofpipedwater
suppliesfromimprovedsourcesinmanylow-andmiddle-incomecountries,whereoverone-
thirdofurbanwatersuppliesarefrequentlyinterrupted[8].
Arecentreviewestimatedthatatleast309millionpeopleworldwideexperienceinterrup-
tionoftheirwatersupplies[9].Intermittentwatersuppliestransmitwaterbornepathogens
[10],increasehouseholdwaterstoragetimes[11–13],andjeopardizehygienepractices[12,
13].Furthermore,wide-mouthedwaterstoragecontainersarevulnerabletocontaminationby
uncleanhands,cups,andotherwaterretrievalvessels[14–16].Arecentsystematicreview
revealedonestudythatreporteda73.0%reductionindiarrheaafterthechangefromintermit-
tenttocontinuouswatersupplies[17].AnothersystematicreviewbyFewtrelletal.[18]
revealedthatimprovementsofthemicrobiologicalqualityofwaterreducedtheriskofdiar-
rhea-relatedmorbidityby31.0%.Safestorageofwateratthehouseholdlevel[3,19–21]and
continuousavailabilityofimprovedwatersupply[10,22]havebeenidentifiedaseffectivemea-
surestopreventdiarrhea.Safewaterstorage,properwater-handlingpracticesandhousehold
levelwatertreatmenthavebeenreportedtoreducetheriskofdiarrheaby25.0%-85.0%[20,
21].Hence,safepipedwatersuppliesalonemaynotbeaguaranteeforpreventingdiarrhea
becauseofpotentialissuesarisingfromalackofcontinuousavailabilityandmicrobiological
contaminationofwaterthroughpoorhouseholdwater-handlingpractices[3,23].
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Pipedwatersupplyinterruptionsandacutediarrhea
AlthoughE.coliisanindicatoroffecalcontaminationofwaterasacauseorcontrolofdiar-
rhea[24,25],theepidemiologyofintermittentwatersuppliesneedstobebetterunderstood
[9,26].UrbanareasinEthiopiaaregrowingrapidly,withslumscoveringabout80.0%of
AddisAbabain2010[27].Intermittentpipedwatersuppliespresentanongoingproblemin
AddisAbaba,especiallyintheslums,despitesignificanteffortsmadebytheCity’sWater
Authority.Thus,itisunknowniftheavailabilityofpipedwaterinAddisAbabaslumsensures
theconsumptionofcleanwaterandreducesacutediarrheaamongunder-fivechildren.
Thisstudyexaminesintermittentpipedwatersupplies,householdwater-handlingpractices,
andPOUwatercontaminationbyE.coliinhouseholdstoredwaterinrelationtoacutediar-
rheaamongunder-fivechildreninslumsofAddisAbaba.Theresultsofthisstudymayassist
Ethiopianwatersupplyofficialsandhealthpolicymakersindesigningprogramsforcontinu-
ousavailabilityofwatertoreducetheincidenceofacutediarrheaamongunder-fivechildren
inslumsofAddisAbabaandotherurbanslumsinEthiopia.
Materialsandmethods
Studyarea
ThestudywasconductedinsevenslumkebelesofAddisAbaba(threekebelesinGulleleSub-
CityinDistrict(Woreda)01andfourkebelesinLidetaSub-CityinDistrict05).Kebeleswere
thelowestadministrativestructuresinAddisAbababefore2011;sincethen,theDistrictshave
becomethelowestadministrativestructures.ThisstudyusedbothkebeleandDistrictdesigna-
tionstobeconsistentwiththeexistingliterature.TheAddisAbabaWaterandSewerage
Authorityisresponsibleforprovidingpipedwatersuppliesfromimprovedsources,thatis
pipedwatermainlyfromsurfacewaterinthenearbyLegadadi,Dire,andGefersareservoirs,
andalsogroundwaterpumpedfromtheAkakiWellfield[28].
InterruptionofthewatersupplyoccursinAddisAbabamainlybecauseoflowcapacityof
waterproduction(duetoscarcityofsurfacewaterforthewatertreatmentplantsduringthe
dryandshortrainyseasons),theoldandpoorlymaintaineddistributionsystem,mechanical
failureandthusneedoffrequentinterruptionforrepairofdistributionsystems[28].Since
occurrencesofintermittentstoppageofthewatersuppliesareoftenunknownaheadoftime
(unlesstheCity’swatersupplyauthorityhasaplannedoutageandmakesanannouncement
aheadoftimethroughthepublicmedia),householdersareinclinedtostorewaterinanticipa-
tionoffuturestoppages.
Studydesignandperiod
Acommunity-basedmatchedcase-controlstudydesignwasemployedfromNovemberto
December,2014.Casesweredefinedasunder-fivechildrenwithacutediarrheaduringthetwo
weeksbeforethesurvey,whereascontrolswereunder-fivechildrenwithoutacutediarrhea
duringthetwoweeksbeforethesurvey.Controlswerematchedtocasesbyageandneighbor-
hoodusingindividualmatching.
Samplesizecalculation
Samplesizewascalculatedusingmatchedcase-controlstudydesignsamplesizeestimation
methods[29]byconsideringPitmanefficiencyassumptionofmatchedpairsamplesize[30].
Amatchedsamplesizeof199pairsusingindividualmatching(1caseto3controls;which
means199cases:597controls)wasconsideredadequatebyassuming1)aprobabilityoftypeI
error5%;2)a90%powerofthetest;3)aprobabilityoftypeIIerror10%;4)aproportion(p)
ofPOUcontaminationofhouseholdstoredwaterbyE.coliamongcontrolscomparedto
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Pipedwatersupplyinterruptionsandacutediarrhea
pipedwatersupplyis41.8%[31];5)expectedoddsratiois1.75;6)a10%non-responserate;
and7)control-to-caseratio(r)is3,basedonPitmanefficiencycriteria[32].Twenty-fiveper-
centmatchedpairsamplesofcaseandcontrolhouseholds(50cases:150controls)weretaken
asadequateforwatersamplesinhouseholdstoredwaterandfrompipedwatersupply.This
25%outofthetotalmatchedpairforwatersampleswasdeterminedbasedonsimilarstudies
[31,33].
Inclusionandexclusioncriteria
Childrenunderfiveyearsofagewithacutediarrheaduringthetwoweeksbeforetheprelimi-
narysurveymightbecomefreeofacutediarrheaduringthesurvey(andalsoviceversa),and
thuswerenotconsideredascases.Whentherewasmorethanoneacutediarrhealunder-five
childinahousehold,oneofthechildrenwasrandomlyselectedbeforeinterviewingthecare-
giver.Duringselectionofcasesandmatchedcontrols,householdshavingunder-fivechildren
whohadfetchedwaterfrompipedwatersuppliesduringthetwoweeksbeforethesurveywere
included.Duringwatersamplingfromdirect-pipedwatersuppliesandhouseholdstored
water,householdswereexcludediftheydidnotstorewaterduringthesurveytime.Under-five
childrenwithbloodyand/orpersistentdiarrheaduringthetwoweeksbeforethesurveywere
excludedbecauseofdysenterybeingafrequentcauseofbloodydiarrheaandthe14-daysor
longerdurationofpersistentdiarrhea.
Caseandcontrolselection
Cases. Therewasnospecificsamplingframeforselectingcasesusingsystematicsampling
techniquesbecausedailyfluctuationsinspecificcasesofacutediarrheawouldmaketheexact
numberofcasesineachDistrictorkebeleduringthetwomonthsofthesurveyperiodunknown.
However,forobtainingrepresentativecasesineachslumDistrict,weperformedapreliminary
survey.Allhouseswithchildrenaged0–59monthswithacutediarrhea(cases)wereenumerated
todeterminethesamplingpopulationofcasesinthetwoDistricts(sevenkebeles).Then,sample
sizeforcaseswasproportionallyallocatedforeachslumkebele.Finally,duringthesurvey,data
enumeratorsidentifiedcasesduringhouse-to-housetransectwalksineachkebeleuntilthepro-
portionallyallocatedsamplesizewasachieved.
Duringtheselectionofcases,diarrheawasidentifiedusingWorldHealthOrganization
(WHO)[34]signsandsymptomsfordiarrhea.WHO[34]definesdiarrheaasthepassageof
threeormoreabnormallyloose,wateryorliquidstoolsperday.However,theWHOdefinition
doesnotspecifytherecallperiodandthetypesofdiarrhea.Inourstudy,caseswereconsidered
tobeonlyacutediarrheausingatwoweekrecallperiodasspecifiedintheWorldGastroenter-
ologyOrganizationglobalguidelinesforacutediarrhea[35].
Controls. Duringtheselectionofcontrols,controlchildrenwerematchedforageand
neighborhoodwithcases.Individualmatchingwascarriedoutonecaseatatimebyselecting
threecontrolsfromtheimmediate(closest)neighborhoodfirstandthencontinuedwith
houseshavingunder-fivechildreninhouse-to-housevisitsduringtransectwalksuntilallcon-
trolsmatchedallcases.Duringthematchingofcontrolsbyneighborhood,noeffortwasmade
toidentifyhousesimmediatelyadjacent;however,casesandcontrolswereinthesamekebele.
Theageofthecontrolwasbasedonthethreeagecategories:controlage=caseage±2months
forinfants(0–11months),±3monthsfortoddlers(12–23months),and±6monthsforchil-
dren(24–59months).Thesethreeagecategoriesofcontrolselectioncriteriawereconsistent
withsomestudies[36,37].Weusedthethreeagecategoriesofmatchingforavailabilityofcon-
trolswithinsimilarorcloselysimilaragewithcases.
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Pipedwatersupplyinterruptionsandacutediarrhea
Fig1.AconceptualhierarchicalframeworkforriskfactorsPOUcontaminationofhouseholdstoredwaterbyE.coliinAddis
Ababaslums,Ethiopia,NovembertoDecember,2014.
https://doi.org/10.1371/journal.pone.0181516.g001
Datacollection
HouseholdsurveydatawerecollectedfromNovembertoDecember,2014onsocio-demo-
graphicandwater-relatedfactors,whichwerepredefinedintheconceptualframework(Fig1).
Somevariablesrepresentingthesefactorswerealsocodedusingtheoperationaldefinitions
giveninTable1.Forbothcaseandcontrolhouseholds,seventrainedfemalenursesandenvi-
ronmentalhealthprofessionalsadministeredthesurveybyinterviewingprimarycaregivers
(mothers)usingapre-testedstructuredquestionnaire.E.colianalysisofwaterfrompiped
watersupplies(privateandpublic[tankerandBono]taps)andhouseholdstoredwaterwas
performedintheAddisAbabaWaterandSewerageAuthoritybacteriologicallaboratoryusing
five-tubeMPN/100mlmethods.
Watersamplecollection. Everyfourthcasehouseholdwasselectedforwatersampling.
Watersampleswerealsotakenfromthematchedcontrolhouseholds.Whenonewatersample
wastakeninacasehousehold,threewatersampleswerealsotakenfromthethreematched
controlhouseholds.Inhouseholdswithmorethanonewaterstoragecontainer,thecontainer
tobewatersampledwasrandomlyselected.Thetypeofpipedwatertapswasidentifiedbyask-
ingeachcaregiverforthesourcefromwhichthewaterhadbeenfetchedduringthetwoweeks
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Pipedwatersupplyinterruptionsandacutediarrhea
Table1. Operationaldefinitionsforcodingvariablesincludedintheanalysis.
Variables Operationaldefinitions
Wide-ornarrow-mouthedwater Wide-mouthed((cid:21)6cm)andnarrow-mouthed(<6cm)[22].Wide-
storagecontainer mouthedindicatedawaterstoragecontainerthatahandcould
enterwhendippingforwaterwithawaterretrievalvessel.
Waterretrievingvesselhavinghandle Retrievingwaterfromwaterstoragecontainereitherbydippingor
orwithouthandle pouringusingavessel(cup,ladleandother)havinghandleor
withouthandle.
Intermittentpipedwatersupply Therewasnocontinuousavailabilityofwaterfrompipedwater
duringthetwoweeksbeforethesurvey.
Pipedwatersupply Municipallypipedwateratprivateandpublictaps[40].Inthisstudy,
publicwatertapsincludedBonoandtankertaps,whereasaprivate
tapwasownedbyonehousehold,butwasalsousedbyoneor
moreotherhouseholds.
POUcontaminationofhousehold POUcontaminationofhouseholdstoredwaterwasindicatedbya
storedwaterbyE.coli greaternumberofE.colipositivetubesinhouseholdstoredwater
comparedtotherespectivepipedwatersupplywherethewater
hadbeenfetched.However,iftherewerethesamenumberofE.
colipositivetubesorzeropositivetubesinthehouseholdstored
wateranddirect-pipedwatersupply;itwastakenasnoPOU
contaminationofhouseholdstoredwaterbyE.coli.
Cleaningofwaterstoragecontainer Washingofwaterstoragecontaineronceduringthetwoweeks
beforethesurvey.
Dailypercapitawaterconsumption(l/ Quantityofwaterconsumedperdaybyeachhouseholdmember
c/d) duringthetwoweeksbeforethesurvey.
FivetubesMPN/100ml 0positivetube*(<2.2E.coliMPN/100ml),1positivetube(2.2E.
coliMPN/100ml),2positivetubes(5.1E.coliMPN/100ml),3
positivetubes(9.2E.coliMPN/100ml),4positivetubes(16E.coli
MPN/100ml)and5positivetubes(>16E.coliMPN/100ml)[39].
E.coli,Escherichiacoli;l/c/d,literpercapitaperday;MPN,MostProbableNumber;POU,Point-of-Use
*Complieswithbacteriologicaldrinkingwaterqualitystandards[nopositiveE.colitubedetected(<2.2E.
coliMPN/100ml)]ofWHOandEthiopia[41,42].
https://doi.org/10.1371/journal.pone.0181516.t001
beforethesurvey.Ifbothcaseandcontrolhouseholdshadfetchedwaterfromthesamepiped
watersupply,onlyonewatersamplewastaken(Fig2).
Allwatersampleswerecollectedusingsterilepolyethylenewatersamplingbottles(250ml).
Collectedwatersampleswerestoredinanice-boxandtransportedtotheAddisAbabaWater
andSewerageAuthority’sbacteriologicallaboratorywithin2hrsofcollectionforlaboratory
analysiswithin2to4hrs.Watersamplingproceduresandtransportofwatersamplestolabo-
ratoryroomsfollowedWHOguidelines[38](S1).Thenumberofwatersamplestakenfrom
pipedwatersupplyandhouseholdwaterstoragecontainersisdescribedinFig2.Watersam-
plesforcasesandcontrolsweretakenconcurrentlyfromthehouseholdstoredwaterandtheir
direct-pipedwatersupply.
WateranalysisforE.coli. Afive-tubemethodofMPN/100mlstandardprocedurewas
usedforE.colianalysisofpipedwatersuppliesandstoredwater.Forlactosebrothmedia
preparations,13gramsoflactosebrothmediumpowderweremixedthoroughlyinlliterof
distilledwateranddispensedin10mlincrementsintoahundred10mltubescontaining
Durhamtubesandthenautoclavedat121˚Cfor15minutesat15poundsofpressureper
squareinch(psi).ForE.coliliquidmediapreparations,37gramsofE.colibrothmedium
powderweremixedthoroughlyinlliterofdistilledwateranddispensedinincrementsof10
mlintoahundred10mltubescontainingDurhamtubesandthenautoclavedat121˚Cfor
15minutes[39].
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Pipedwatersupplyinterruptionsandacutediarrhea
Fig2.Acommunity-basedindividualmatchedcase-controlstudyflowchartofAddisAbabaslums,Ethiopia,NovembertoDecember,
2014.
https://doi.org/10.1371/journal.pone.0181516.g002
Forthegrowthofbacteria,apresumptivephaseofinoculationof10mlofwatersamplefor
each5tubescontainingthepreparedlactosemediawasdispensedandincubatedinanincuba-
torat44.5˚Cfor24to48hrs.Tubeswithgasbubbleformationand/orcloudycolorwithin24
hrswerepositiveforbacteriaandtheremainingnegativetubeswerekeptforadditional24hrs.
ForconfirmationofthepresenceofE.colifrompositivetubes,E.coliselectivemediawasused.
10mlfrom20mloflactoseandsamplewerepouredinto10mlE.colipreparedmediaand
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Pipedwatersupplyinterruptionsandacutediarrhea
incubatedfor24to48hrsat35.5˚C.Subsequently,forcompletedphase,tubespositiveforE.
coliwereusedtoestimatetheconcentrationofE.coli[39].ThenumberofE.colipositivetubes
andtheirestimatedconcentrationsofE.coliMPN/100mlareshowninTable1.
Ethicalconsiderations
AnethicalapprovalletterwasobtainedfromtheInstitutionalEthicalReviewCommitteeof
WolloUniversity,CollegeofMedicineandHealthSciences.Thatcommitteeapprovedboth
theprotocolandtheconsentforms.Writteninformedassentandconsentwereobtainedfrom
thecaregiversofparticipatingchildren(bothcasesandcontrols),assentonbehalfofthepartic-
ipatingchildren,andconsentforthecaregiversthemselves.
Theprojectprovidedoralrehydrationsalttreatmentforacutediarrhealunder-fivechil-
dren.Notreatmentwasgiventoacutediarrhealunder-fivechildrenwhowerealreadybeing
treatedatahealthfacilityduringtwoweekspriortothesurveyandthosewhohadalready
recoveredfromacutediarrheaduringthesurvey.Caregiverswereadvisedtovisitpublichealth
facilitieswhentherewasnorecoveryaftertwodaysoftreatment.Thisstudywasconducted
accordingtotheprotocolandethicalprinciplesoftheDeclarationofHelsinkibytheWorld
MedicalAssociation[43]andalsototheprinciplesthatgovernmedicalresearchinvolving
humansubjectsspecifiedbytheCouncilforInternationalOrganizationsofMedicalSciences
[44].
Statisticalanalysis
DatawereenteredusingEpiDataVersion3.1(EpiDataAssociation,Odense,Denmark)soft-
wareandexportedtoSTATAVersion13.0statisticalsoftware(StataCorpLP,CollegeStation,
TX)fordataanalysis.Beforedataanalysis,datawerecleanedusingtwostepsasdescribedelse-
where[45].Descriptivestatistics[n(%)]werecarriedoutforcasesandcontrols,including
means(±SD(standarddeviations)forcontinuousvariables.
DataanalysiswasbasedonourconceptualhierarchicalframeworkshowninFig1usinga
conditionallogisticregressionmodel.Themodelingstrategyinvolvedestimatingunadjusted
matchedoddsratio(unadjustedmOR)andadjustedmORofthestudiedvariableswithacute
diarrheaat95%CI.Thus,dataanalysisofunadjustedmORandadjustedmORwasemployed
onlyforthefullypaireddatabyconditionallogisticregressionmodel,whiletakinginto
accountthematchedanalysisofcasesandcontrols.Ouranalysisdidnotconsiderchildren’s
agesandneighborhoodssinceweusedbothasmatchingvariablesforcontrolswithcasesdur-
ingthestudydesign.VariablesinFig1wereclassifiedasdistal(block1),intermediate(blocks
2,3,4),andproximate(block5)determinantsaccordingtoourhierarchicalframework,which
wasdevelopedbasedonourstudycontextandsimilarmethodsdescribedelsewhere[46,47].
Bivariateanalysisidentifiedvariablesassociatedwithacutediarrheaatp<0.05.Fromthe
bivariateanalysis,variablesthathadasignificancelevelofp<0.2ineachblockwereretained
forinclusionintothemultivariableanalysisofhierarchicalconditionallogisticregressioncon-
sistingoffivemodels(models1,2,3,4and5)andafinalmodelbasedonthefiveblocksofvar-
iablesinFig1.Thepurposeofeachmodelwastoidentifypotentialconfoundersinastep-by-
stepfashion,bytakingintoaccountthelevelsofinfluenceasdistal,intermediate,andproxi-
matefactors.Thevariablesthatremainedsignificantlyassociatedwithacutediarrheaatp<0.2
inthemultivariableanalysisofeachmodelwereincludedinthesubsequentmodel[48,49].
Thefinalmodelincludesonlyvariableswithap<0.2frommodel5.Inthefinalmodel,vari-
ablesatp<0.05wereconsideredasstatisticallysignificantandindependentlyassociatedwith
acutediarrhea.
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Results
Socio-demographiccharacteristicsofcasesandcontrols
Theresponserateforfullymatchedpaireddatafromthesurveyandwatersamplewas190
matchedpairs(95.5%)and48matchedpairs(96.0%),respectively.Ninecasesdidnotmatch
anycontrols.Nowatersamplesweretakeninonecasehouseholdthathadnostoredwaterfor
watersamplingandfromonecontrolhouseholdthatdidnotcollectwaterfromapipedwater
supply(Fig2).
Themeanageofthecaregiverswas28.4(±5.5)yearsforcasesand29.8(±6.2)for
controls.Themeanmonthlyhouseholdincomewas$36.1(±22.8)USforcasehouseholds
and$52.2(±27.4)USforcontrolhouseholds(Table2).Outof190cases,54.2%weremales
and45.8%werefemales,whereasoutof570controls,52.2%weremalesand47.8%were
females(Table3).Theagedistributionofcasesandcontrolswas136(17.9%)between
0–11monthsold,208(27.4%)between12–23monthsold,and416(54.7%)between24–59
monthsold.
Intermittentpipedwatersuppliesanddailypercapitawaterconsumption
Overtwo-thirds(69.7%)ofcontrolhouseholdsand63.7%ofcasehouseholdsobtainedwater
fromprivatetaps,whereas30.3%ofcontrolhouseholdsand36.3%ofcasehouseholdsfetched
waterfrompublictaps(Table4).Overall,meandurationofintermittentpipedwatersupply
duringthetwoweeksbeforethesurveywas4.3daysincasehouseholds,and3.9daysincontrol
households.Averagedailypercapitawaterconsumptionperpersonwas11.5and14.6liters
amongcaseandcontrolhouseholds,respectively(Table2).
Householdwater-handlingpractices
Householdsstoredwaterforaminimumofhalfadayandamaximumof9.5daysduring
thetwoweeksbeforethesurvey.Theaveragewaterstoragedurationwas3.1daysforcase
householdsand2.2daysforcontrolhouseholdsduringthetwoweeksbeforethesurvey
(Table2).Waterwasstoredfor3.5daysorlessduringthattimeperiodby62.6%ofthecase
householdsand76.1%ofthecontrolhouseholds.Characteristicsofhouseholdwater-han-
dlingpracticesandtheresultsofthebivariateanalysisofacutediarrheaaresummarizedin
Table4.
Table2. Characteristics[mean(±SD)]ofcaseandcontrolhouseholdsinAddisAbabaslums,Ethio-
pia,NovembertoDecember,2014.
Case Control
households households
(N=190) (N=570)
Variables Mean SD Mean SD
Ageofcaregivers(years) 28.4 5.5 29.8 6.2
Monthlyhouseholdincome($US1) 36.1 22.8 52.2 27.4
Householdsize(persons) 5.4 1.9 5.4 1.9
Intermittentpipedwatersupply(dayswaternotavailablepertwoweeks) 4.3 1.7 3.9 2.7
Dailypercapitawaterconsumption(l/c/d) 11.5 4.9 14.6 5.1
Waterstorageduration(days) 3.1 2.2 2.2 2.0
SD,Standarddeviations;l/c/d,literpercapitaperday;$US,UnitedStatesDollars.
1Theaverageexchangerateof$1US=20.0ETB(Ethiopiabirr)fromNovembertoDecember,2014.
https://doi.org/10.1371/journal.pone.0181516.t002
PLOSONE|https://doi.org/10.1371/journal.pone.0181516 July19,2017 9/19
Pipedwatersupplyinterruptionsandacutediarrhea
Table3. Bivariateanalysisofsocio-demographiccharacteristicswithacutediarrheaamongunder-fivechildreninAddisAbabaslums,Ethiopia,
NovembertoDecember,2014.
Cases(N=190) Controls(N=570)
Variablesinblock1 n(%) n(%) UnadjustedmOR(95%CI)§
Ageofcaregivers(years)
<25 39(20.5) 98(17.2) 1.5(0.9–2.7)
25–34 119(62.6) 350(61.4) 1.3(0.8–2.1)
>34 32(16.9) 122(21.4) 1
Monthlyhouseholdincome($US)
Lessthan$50US 133(70.0) 268(47.0) 3.0(2.1–4.4)
$50USorabove 57(30.0) 302(53.0) 1
Housingownership
Rentorother* 175(92.0) 515(90.4) 1.3(0.7–2.3)
Ownhouse 15(8.0) 55(9.6) 1
Educationofcaregivers
Didnotattendformalorinformaleducation** 83(43.7) 145(25.4) 2.4(1.7–3.4)
Attendedformaland/orinformaleducation 107(56.3) 425(74.6) 1
Householdsize
6ormorepersons 84(44.2) 237(41.6) 1.1(0.8–1.6)
2–5persons 106(55.8) 333(58.4) 1
Maritalstatusofcaregivers
Unmarried 62(32.6) 101(17.7) 2.3(1.6–3.4)
Married 128(67.4) 469(82.3) 1
Employmentofcaregivers
No 89(46.8) 258(45.3) 1.1(0.8–1.5)
Yes 101(53.2) 312(54.7) 1
Childgender
Male 103(54.2) 298(52.3) 1.1(0.8–1.5)
Female 87(45.8) 272(47.7) 1
Numberofunder-fivechildrenperhousehold
2–4children 44(23.2) 119(20.9) 1.2(0.8–1.7)
1child 146(76.8) 451(79.1) 1
UnadjustedmOR,Unadjustedmatchedoddsratio;CI,Confidenceinterval.
*Housesthatwereillegallyconstructedandhadnoownerorhousestemporarilyprovidedbyfamiliestorelativesorotherpersons.
**Unabletoreadorwritebasedonself-reporting.
§DenotesunadjustedmORusing95%confidenceintervalfrombivariateconditionallogisticregressionanalysisinmatchedcase-controlpairs.
1Referencecategory.
https://doi.org/10.1371/journal.pone.0181516.t003
E.colicontaminationatpipedwatersuppliesandinhouseholdstored
water
Inthe192householdswherewatersamplesweretakenfromtheirpipedwater,thebacteriolog-
icalqualitywas<2.2E.coliMPN/100mlin66.7%ofthecasehouseholdsand62.5%ofthe
controlhouseholds;and2.2E.coliMPN/100mlin29.2%ofthecasehouseholdsand31.2%of
thecontrolhouseholds.Overall,furthercontaminationbyE.coliatPOUinhouseholdstored
waterwasfoundinmost40(83.3%)ofthecasehouseholdsand75(52.1%)ofthecontrol
households.Inthebivariateanalysis,contaminationofpipedwatersuppliesbyE.coliwasnot
associatedwithacutediarrhea(unadjustedmOR=0.7;95%CI:0.3–1.5)(Table4).Thestored
waterof42(87.5%)casehouseholdsand112(77.8%)controlhouseholdsdidnotmeettheE.
PLOSONE|https://doi.org/10.1371/journal.pone.0181516 July19,2017 10/19