UvA-DARE (Digital Academic Repository) Malaria during pregnancy in Rwanda Rulisa, S. Link to publication

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1 UvA-DARE (Digital Academic Repository) Malaria during pregnancy in Rwanda Rulisa, S. Link to publication Citation for published version (APA): Rulisa, S. (2014). Malaria during pregnancy in Rwanda General rights It is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), other than for strictly personal, individual use, unless the work is under an open content license (like Creative Commons). Disclaimer/Complaints regulations If you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. UvA-DARE is a service provided by the library of the University of Amsterdam ( Download date: 23 Nov 2018

2 CHAPTER2 MalariaPrevalence,SpatialClusteringandRiskFactorsin alowendemicareaofeasternrwanda:acrosssectional Study StephenRulisa 1,3,FredrickKateera 2,6,JeanPierreBizimana 5,Steven Agaba 3,JavierDukuzumuremyi 3,LisetteBaas 3,JeandeDieuHarelimana 3, PetraF.Mens 2,3,4,KimberlyR.Boer 3,4,PeterJ.deVries 2,3,7 1.UniversityTeachingHospitalofKigali,NationalUniversityofRwanda,Kigali,Rwanda, 2.AcademicMedicalCenter,DivisionofInfectiousDiseases,TropicalMedicineandAIDS, Amsterdam,TheNetherlands, 3.AmsterdamInstituteforGlobalHealthandDevelopment,INTERACTProject,Kigali,Rwanda, 4.RoyalTropicalInstitute/KoninklijkInstituutvoordeTropen(KIT),KITBiomedicalResearch, Amsterdam,TheNetherlands, 5.GeographyDepartment,FacultyofScience,NationalUniversityofRwanda,Butare,Rwanda, 6.MedicalResearchCentre,RwandaBiomedicalCentre,Kigali,Rwanda, 7.DepartmentofInternalMedicine,Tergooiziekenhuizen,Hilversum,TheNetherlands Publishedin:PLOSONE20138:e69448 MalariaduringpregnancyinRwanda 23

3 Abstract Background: Rwanda reported significant reductions in malaria burden following scale up of control intervention from 2005 to This study sought to; measure malaria prevalence, describespatialmalariaclusteringandinvestigateformalariariskfactorsamonghealthcentre presumedmalariacasesandtheirhouseholdmembersineasternrwanda. Methods: A twostage health centre and householdbased survey was conducted in Ruhuha sector,easternrwandafromapriltooctober2011.atthehealthcentre,data,includingmalaria diagnosisandindividuallevelmalariariskfactors,wascollected.athouseholdsoftheseindex cases,afollowupsurvey,includingmalariascreeningforallhouseholdmembersandcollecting householdlevelmalariariskfactordata,wasconducted. Results:Malariaprevalenceamonghealthcentreattendeeswas22.8%.Atthehouseholdlevel, 90households(outof520)hadatleastonemalariainfectedmemberandtheoverallmalaria prevalenceforthe2634householdmembersscreenedwas5.1%.amonghealthcentreattendees, the age group 5 15 years was significantly associated with an increased malaria risk and a reportedownershipof4bednetswassignificantlyassociatedwithareducedmalariarisk.atthe householdlevel,agegroups5 15and>15yearsandbeingassociatedwithamalariapositiveindex casewereassociatedwithanincreasedmalariarisk,whileanobservedownershipof4bednets wasassociatedwithamalariariskprotectiveeffect.significantspatialmalariaclusteringamong householdcaseswithclusterslocatedclosetowaterbasedagroecosystemswasobserved. Conclusions:Malariaprevalencewassignificantlyhigheramonghealthcentreattendeesandtheir household members in an area with significant household spatial malaria clustering. Circle surveillance involving passive case finding at health centers and proactive case detection in householdscanbeapowerfultoolforidentifyinghouseholdlevelmalariaburden,riskfactorsand clustering. MalariaduringpregnancyinRwanda 24

4 Introduction From2005to2010,Rwandaachievedthe2005globalcommunitycommitmentofreducingthe malariaburdenbyatleast50%[1].duringthisperiod,arapidmalariaassessmentconductedat 30outof40HospitalsinRwandashowedreductionsof;74%amongconfirmedoutpatientscases ofallages,26%inslidepositivityrates,65%amonginpatientsofallages,and55%inmalaria deaths[2].thesegainsfollowedrapidscaleupofinsecticidetreatedmosquitonets(itns),indoor residual spraying (IRS), use of artemisinin combination therapies (ACTs) and laboratory confirmationofpresumedmalariacaseswithmicroscopy(athealthfacilities)andrapiddiagnostic tests (RDTs) (by community health workers) as recommended by WHO s Roll Back Malaria program [1]. Despite these gains, malaria still causes significant morbidity; 7.8% of all febrile patientspresentingatthehealthcentre(hc)hadmalariaand12.9%ofallagemortalitywere malaria associated in 2010, with a malaria resurgence recorded in 2009 [2,3,4]. These observationshighlightthefragilityofgainsinmalariareductionachieved,especiallyinareaswith ahighbaselinemalariatransmissionpotential. Figure2.1.LocationofRuhuhaSector(Red),BugeseraDistrict(Grey)inRwanda. Scource:MINITRACO/CGISNUR,2001andNSIR2006. MalariaduringpregnancyinRwanda 25

5 Current anecdotal Rwandan national routine data suggests a heterogeneous spatial malaria distribution with the entire population remaining at risk with the exception of the very high altitude zones [3,5]. Malaria heterogeneity has been reported across the different malaria endemicsettingsandhasbeenattributedtoriskfactorsincludingaltitude,climate,occupation andsocioeconomicstatus[6,7,8,9,10].however,atallmalariaendemicitylevels,andparticularly inlowincidenceareas,malariatendstoclusterin hotspots and hot populationsthatbecome sourcesofcontinuedinfection.wedefineda hotspot ofmalariatransmissionas ageographical partofafocusofmalariatransmissionwheretransmissionintensityexceedstheaveragelevel [11].Inacommunity,asymptomaticandminimallysymptomaticmalariacases,whosesymptoms maynotbesevereenoughtoseekcare,canserveassignificantparasitereservoirsformaintaining transmission[7,8,12]. Active and timely identification of these hotspots and associated risk factors is essential for targeting interventions to optimize malaria control [13]. Risk factors associated with malaria clusteringforwhichwealsoinvestigatedincludedistanceofhouseholds(hhs)frompotential mosquitobreeding sites, house roofing and wall materials and bednet use [7]. In Rwanda, however,thereispaucityofsystematichhstudiesonmalariaburdenorassociatedriskfactors withmostreporteddatabeingaggregatedroutinehealthfacilitydata.despiteitstendencyto underestimate malaria burden, routine data can be helpful in reflecting malaria trends [14], particularlyinlowmalariaincidencesettingswherethemajorityofthepopulationaccesshealth services from the reporting health facilities. The passively identified health facility cases may reflectmalariatransmissionlevelsinplaceswheremalariacasestendtoclusterintimeandplace. Indexcasesmayalsoactasentrypointstocommunityprogramswhereidentificationofhotspots couldbetargetedforoptimalmalariacontrol.malariahotspotsmayservetoperpetuateresidual malariatransmissioninlowtransmissionseasonsandhindereffortstoeliminatemalaria[15].in this study, we used HC attendees with presumed malaria as entry points for reactive case identificationofmalariainfectionsatthehhlevel.inatwophasehealthfacilityandhhcross sectionalsurvey,weemployedacirclesurveillancetechniquetomeasuremalariaburdenand evaluateforassociatedmalariariskfactors.wealsoinvestigatedforspatialmalariaclustering usinggeographicalinformationsystem(gis)andspatialstatisticaltechniques[16,18]. MalariaduringpregnancyinRwanda 26

6 MaterialsandMethods EthicalStatement Ethical approval was granted by Rwanda National Ethics Committee. Prior to study initiation, sector and community leaders were informed about the study and their support and verbal consent requested. Written consents were obtained from adult participants and parents/guardiansofparticipatingchildrenandfromheadsofhhsortheoldestpersonpresent forthehhsurveys. Studyarea ThecompletesurveywasconductedinRuhuhaSector,Bugeseradistrict[19],EasternRwanda (Figure2.1).Thesectorcovers54km2,hasapopulationofabout19,606personslivingin4279 HHs. It is predominantly rural and traditionally a high malaria endemic area. Ruhuha sector, surroundedbylowlandmarshesandwaterstreamsdrainingintotheakagerariversystem,is separatedfromburundibylakecyohohainthesouth. StudyDesignandParticipants AtwophasecrosssectionalsurveywasconductedbetweenAprilandOctober2011.First,afever surveywasconductedamongpatientspresentingatruhuhahealthcentre(rhc)withafeveror historyoffeverinthelast24hours.patientsofallageswererecruitedandaftersigningthe informedconsentform,malariadiagnosisbymicroscopyandindividuallevelriskfactordatawere collected. Thereafter, study participants were invited to participate in a followup HH survey wherehhlevelmalariariskfactordatawascollectedandmalariascreeningforallhhmembers performed. MalariaduringpregnancyinRwanda 27

7 StudyProcedures Healthcenter(HC)feversurvey At the HC, an interviewer administered questionnaire, adapted from the Measures group Demographic Health Surveys tools and previous studies [20,21], was administered to adult patients or, in the case of minors, to parents/guardians of the children. The pretested questionnaire was administered by studytrained personnel. Data collected included personal demographics, fever characteristics, malaria perception, knowledge and practices including malariapreventivemeasures,andhousestructuralfeatures(wallsandroofs). Preparationofbloodfilms,microscopicexaminationandqualityassurance ToidentifymalariaamongHCattendees,Giemsastainedthickandthinbloodfilmswereprepared and read by two independent experienced microscopists at the RHC laboratory. A third microscopistbasedatnationalreferencelaboratory(nrl)settleddiscrepanciesbetweentwo readings.parasitenegativeresultswerebasedonscreeningof100microscopicfieldsat1000x magnification.malariaparasiteswerecountedagainst200whitebloodcellsonthickbloodfilms forenumerationofparasitedensityandthinsmearsusedforspeciesidentification.inaddition, 10%ofallmicroscopyslidesweresenttotheNRLforexternalqualitycontrol. Householdsurvey HCrecruitedstudyparticipants(regardlessoftheirmalariadiagnosisstatus)whoconsentedtoa homevisitandprovidedhhlocatorinformationwerevisited1to4monthslaterforafollowup HHsurvey.Atthisvisit,allHHswereenumeratedandassignedauniqueidentificationnumber. AnintervieweradministeredquestionnairewasusedtocollectdataonHHlevelmalariariskfactor characteristics including, bednet availability, type, integrity and use, HH water sources and environmentalfactors. MalariaduringpregnancyinRwanda 28

8 Rapiddiagnostictest(RDT)screening Inadditiontothequestionnairedata,allHHmemberswerescreenedforpresenceofmalaria parasites to measure asymptomatic or minimally symptomatic parasitaemia prevalence using RDTs(FirstResponse ComboMalariaAg(pLDH/HRP2)cardtest,PremierMedicalCorporationLtd, India).IfHHmemberswerenotathomeatthetimeofthesurvey,theywereactivelysoughtout and subsequently screened by the field team. RDTs were performed according to the manufacturer sinstructionbytrainedfieldteammembers.allrdtsusedwerefromonebatch thatwasdirectlyobtainedthroughthemanufacturerandstoredaccordingtothemanufacturer s recommendations. However, no external quality control was done on these RDTs. Followup confirmatory microscopy was provided at the Ruhuha HC for all RDTpositive individuals to confirmaccuracyandinformamalariatreatmentdecision. Mappinghouseholdsandgeographicalfeatures. GIS was used to capture, manage and geographically integrate data from different sources. Location data for each HH and key geographical feature was collected using a handheld GPS receiver,gpsmap60csx(garminetrexlegend,garmininternationalinc.usa).digitizeddata frompreexistingshapefilesprovidedbaselayers(topography,landuse,riversandsurfacewater) onwhichstudydatawasoverlaidintoonegeodatabasecompatiblewitharcgis10.boundaries shapefilesofadministrativeunits( cells ),wetlands,waterbodiesandtheelevationcontourlines forruhuhasectorwereobtainedfromthegisremotesensingtrainingandresearchcentreof thenationaluniversityofrwanda. Statisticalanalysis StatisticalanalysiswasperformedusingSTATAsoftware(version12,CollegeStation,TX,USA). Univariateanalysistoassessformalariariskforallvariableswasdoneusinglogisticregression andvariableswithpossiblemalariarisk(p<0.2)wereincludedintheinitialmultivariatelogistic regressionmodel.hhdatawasanalyzedusinggeneralizedestimatingequation(gee)modelswith adjustmentforhhlevelmalariacaseclustering.thelevelofsignificanceforstudystatisticswas MalariaduringpregnancyinRwanda 29

9 p<0.05andwaldtestswereusedtoquantifyvariableeffectsinthemodel.possibleinteraction effectswerealsoassessedfor. Spatialclustering TheKulldorffspatialscanstatistic,usingSaTScanTMversion9.1.1software( wasusedtotestforspatialclusteringofmalariacasesand/ortodeterminewhetherthecases weredistributedrandomlyoverspace[kulldorff&nagarwalla.[1995]].hhs,usedastheunitof analysis, were located using the Cartesian coordinate system to specify coordinates with the maximumspatialclustersizesetat50%ofthepopulationatrisk.asinotherstudies,satscan generatedcircularwindowsofdifferentsizesfordetectingclustering[22,23]. Thenumberofcasesineachwindowwascomparedtotheexpectednumberofcasesbasedon thetotalnumberofcasesandpopulationsize.weusedpurelyspatialanalysesbasedonthe Bernoulliprobabilitymodelthatisappropriatefor0/1eventdatasuchascases/controls.The controlsrepresentedthebackgrounddistributionpopulation.thepvaluewasobtainedfroma likelihoodratiotestbasedonmontecarlosimulationreplicationsofthedataset.spatialscans wereperformedforbothhcattendeeandhhmembercases.ahccasewasdefinedasbeing microscopypositivewithhccontrolsdefinediftheyweremicroscopynegative;ahhmember wasdefinedasbeingacaseiftheywereidentifiedasrdtpositivewithhhcontrolsdefinedifthey wererdtnegative. Results Intotal,769HCattendeeswhopresentedwithfeverorwithahistoryoffeverinlast24hoursat theoutpatientclinicwerescreened.ofthe769;175(22.8%)werediagnosedwithmalaria,458 (59.6%)werefemale,277(36.0%)wereaged<5years,147(19.1%)aged5 15yearsand345(44.9) aged>15years. Aflowchartofstudyparticipantenrolment,malariascreeningandMalariaPrevalence,Clustering and Risk Factors participation is shown in Figure 2.2. HH visits were planned for all 769 HC attendees. MalariaduringpregnancyinRwanda 30

10 Figure2.2:Flowchartofstudyparticipantsandprocedures However,becauseofthelongperiodbetweenHCcaseenrolmentandHHsurvey(1 4months versustheplanned2 4weeks)andtheinaccuratelocationdatareportedbystudyparticipants, thehhsurveywasnotconductedinhhsof200indexparticipants.amonghcattendees,malaria prevalencewascomparablebetweenthosewhosehhwerenotvisited(30.5%(ci )and thosevisited.ofthe557(72.4%)surveyedhhs,520hhshadcompletedata.onlydatafromthese 520HHswereanalyzed.Intotal,2634HHmemberswerescreenedformalaria.Ofthe2634,599 (22.2%)wereaged<6years,763(28.3%)aged6to15yearsand1331(49.4%)aged>15years. Only90(17.3%)HHshadatleastonememberdiagnosedwithmalariaandtheoverallmalaria prevalence(rdtconfirmed)was5.1%(95%ci ).AllvisitedHHshad1bednetandin total,873bednetswereobserved.hhbednetandindoorresidualsprayingcoveragebyselfreport MalariaduringpregnancyinRwanda 31

11 were97.1%and98.2%,respectively.basicknowledgeaboutmalariawashigh,with696(91%) reportingbednetsastheprinciplemalariapreventivemeasurewhile748(97.3%)reportedthat feverwastheprincipalmalariasymptom.interestingly,447(82.5%)ofhhsvisitedhadbednetsin theirpossessionbutthesewerenotphysicallyhung(table2.1) UnivariateAnalysis Results of univariate analysis for individual and HH (after adjusting for possible houselevel clustering of cases) risk factors are displayed in Tables 2.2 and 2.3, respectively. Malaria risk amonghcattendeeswasassociatedwithbothageandreportedbednetownership.compared tochildren5years,malariaprevalencewasthreetimeshigherinthe5 15yearoldswhilea reported ownership of 4 bednets was associated with a significant protective effect. HC attendeeswereevaluatedforsymptomspredictiveofhavingclinicalmalaria.havingameasured fever(37.5 C)atpresentationwasassociatedwithhigheroddsofmalariariskthannofever. SimilartoHCcases,malariariskamongtheirHHmemberswassignificantlyassociatedwithage and observed bednet coverage. Additionally, HH members living in houses made of wood/mud/tent, when compared to those HH members living in dwellings whose walls were madeofstoneorbricks,andhhownershipofaninhouseopenwatervesselwereassociated withhigheroddsofmalaria. MalariaduringpregnancyinRwanda 32

12 Table2.1Reportedandobservedbednet characteristics MultivariateAnalysis At the individual level, an adjusted multivariatelogisticregressionmodelshowed significantlyhigheroddsofclinicalmalariarisk amongchildrenaged5 15years(OR=3.02,P value<0.0001)butaprotectiveeffectivewas notedinthosewithareportedownershipof4 ofmorebednets(or=0.352,pvalue0.003). Having a fever (37.5uC) was predictive of having clinical malaria (OR= 1.64, P value 0.011). House level malaria risk remained significantly associated with age, type of materialhhdwellingwasmadeof,observed bednetcoverageandmalariastatusofindex caseafteradjustingformalariacaseclustering inhhs(table2.1.andtable2.3).comparedto the 5 year age group, malaria risk was significantlyhigheramongthe6 15yearage group (OR = 2.44, Pvalue <0.0001) but interestingly lower, albeit with a borderline statistical significance, among the16 year agegroup(or=0.58,pvalue0.047).livingin dwellings made of wood or mud or tent materialwasassociatedwithahighermalaria riskwhileanobservedownershipof4more bednets was associated with a protective effect. MalariaduringpregnancyinRwanda 33

13 Malaria Clustering Malaria positivity among HC attendees was significantly correlated with a HH having at least one confirmed member (OR = 2.31, P=0.001) but no spatial clustering for HC malaria cases was observed. However, three clusters of HHs with significantly higher risk than expected RDT tested members were identified (Table 2.4). These HH clusters were located; 1. North East (radius of 2.04 Kilometers (Kms), relative risk of 3.40 and P value ), 2. South (radius of 0.51 Kms, relative risk of 5.6, (P value ), and 3. a smaller cluster (not indicated in Figure 2.3) of only one HH (where 4 of its members tested RDT positive) with a relative risks of 20.8, P value (Figure 2.3). Two of these clusters (1 and 2) were located next to waterͳbased agroͳecosystems. Figure 2.3: Spatial malaria clusters and location of Hhs. (Yellow dotsͳcontrol HH with no malaria infected case and small Red dotsͳ case with at least one malaria infected case). * The used administrative boundaries and geographic features shape files were obtained from the Centre for Research and Training in GIS and Remote Sensing of the National University of Rwanda Malaria during pregnancy in Rwanda 34

14 Table2.2:HealthFacilityattendeecharacteristicsandmalariariskfactors MalariaduringpregnancyinRwanda 35

15 Table2.3:Householdcharacteristicsandmalariariskfactors MalariaduringpregnancyinRwanda 36

16 Table2.4:Spatialclusteringofthemorethanexpectedhouseholdcases Discussion Inthisstudy,membersofHHswheretheindexcasehadclinicalmalariashowed1.3timesgreater oddsofbeingmalariainfectedcomparedtomembersofhhwheretheindexpatientwasmalaria negative.comparablefindingsofagreaterriskformalariainfectionamonghhmembersofahc identifiedclinicalmalariacasehavebeenshownbystresmanetal.(2010)inzambia[24].these findingssupportthevalueofcirclesurveillanceas auseful toolforstudyinghhlevelmalaria burden,riskfactorsandclustering.inthisstudy,slide/rdtpositivityratesof22.8%and5.1% amonghcmalariapresumedcasesandhhbasedasymptomaticcasesrespectivelywerefound. ThisdemonstratesthatcirclesurveillancecanshowdifferencesinHHmalariariskandclustering, eveninareasofhighmalariaprevalenceasinruhuha.apartfromlivinginahhwheretheindex casehadmalaria,riskfactoranalysisidentifiedparticipant sageandareportedownershipofa4 bednetasvariablesthat,eitheraloneorinunison,significantlyinfluencedmalariarisk.compared tochildrenaged,5year,olderchildrenandadultshadahigherriskofparasitecarriage,forboth HCattendeesandHHmembersgroups. Thisisincontrasttopreviousfindingsofahighermalariariskinchildren<5years[25].However, a shift to higher malaria risk among older age groups has been reported after the increased coverage with insecticidetreated bednets and the observed followup reduced malaria transmissioninsomecommunities[26,27].thereductionsinmalariatransmissionmaydecrease theriskofmalariainoculationandinfectionsleadingtoanincreaseintheageatwhichmalaria infectionsarefirstacquired.additionally,thereisagreaterlikelihoodofyoungeragegroups(<5 yearolds)usingmalariapreventivebednetscomparedtotheiroldersiblings,althoughthisdata wasnotcollectedinthisstudy[26]. Inthisstudy,thereportedandobservedownershipofbednetswasassociatedwithsignificant malariaprotectiveeffect.thisprotectiveeffectofinsecticidetreatedmosquitonetusehasalso MalariaduringpregnancyinRwanda 37

17 beenaffirmedinmultiplepreviousstudies[28].ruhuhasectorisatraditionallyhightransmission settingwith high bednet coverage.thishigh coveragefollowsthegovernment smassivefree bednetdistributionaftercampaignsrunbetween2009to2011inwhichgovernmentaimedto achieve universal bednet coverage [5,29,30]. Study participants reported a good level of knowledge of malaria symptoms, transmission and preventive measures with over 82% of respondentsreportinguseofbednetsthenightbeforethesurvey. However,inonly18%ofvisitedHHswasabednetfoundphysicallyhungontoabedorasleep spacesuggestingthatbednetusemaybesuboptimal.possiblereasonsforsuboptimalbednet use may be associated with local house structures and/or sleeping arrangements for the HH members.mosthousesinruhuhahave1 2bedroomswithlimitedstructuresonwhichtohang bednets. Additionally, most occupants share sleeping spaces on the floor. These factors may complicateuseofavailablebednetsandpartiallyexplainthelowbednethangingratesobserved andlimitedbednetprotectiveeffectsinhhswithbednets.studiesexploringhowtooptimise bednet usage and effectiveness are recommended. In this study and others, the quality of housing,apartfrombeinganindicatorofhheconomicstatushasbeenreported,toinfluencethe easewithwhichmosquitoescanenterandhideinahomeandhencecontributetomalariarisk [7,31,32].Occupantsofhouseswithwallsmadeofmud/grass/woodhad1.3timesgreaterodds (Pvalue0.016)ofhavingatleastonemalariacasemorethanthoselivinginhouseswithwalls madeofbrickorstone.however,interventionstoaddresstypeofhousingasamalariariskfactor are complex and difficult to achieve and are rarely components of public health programs. A currentcampaigninrwandatophaseoutgrassthatchedhouses(locallyknownas nyakatsi ) andreplacethembyhousesmadeofbrickandironsheetroofscouldimpactmalariatransmission. For high transmission countries where essential clinical services are adequately available, the transition from control to elimination is recommended at SPR of <5% [12]. Achieving pre eliminationlevelsinruhuha,givencurrentsprof>22%,willprobablyrequireintroductionof novelarearelevantinterventionstosupplementexistingcontroltools(mainlyitnsandirs).as malariatransmissiondeclines,acommunitybasedevaluationoftransmissionintensityandsize ofinfectiousreservoirwillberequired.inthisstudy,malariaprevalenceamonghhmembersby RDT was 5.1%. However, since RDTs have a lower sensitivity, as compared for example to molecular tools, the level of true malaria infection prevalence among the predominantly asymptomaticcarrierhhmembers,mayhavebeenunderestimated[33,34].inaddition,thehh MalariaduringpregnancyinRwanda 38

18 surveywasconducted1to4months,ratherthantheplanned2 4weeks,aftertheinitialHC basedfeversurvey.thisdelaymayhavecomplicatedafaircomparisonofmalariariskbetween HCindexcasesandtheirHHmembers.RuhuhasectorisservedbyonlyoneHCmanagedprimarily bycommunityhealthworkerswithmostchildren5years. Theareapopulationisthereforechallengedbyinadequateaccesstohealthcare.Consequently, malariadatareportedfromthishealthcentremayunderestimatethepopulationmalariaburden. ThisfurthercomplicatesafaircomparisonofhealthcentreversusHHlevelmalariarisk[13]. TwohundredHHscouldnotbeidentifieddueto;wrongdirections,nonexistingHHsand,possibly, outofareastudyparticipantswhogavewrongdata.giventhedelayinthefollowuphhsurveys andthesignificantlosstofollowupofindexcases,arepeatrobustreactivecaseidentification study to assess for clustering, particularly in areas of lower malaria transmission intensity, is recommended [12,15]. In this study, HH cases were RDT confirmed while HC cases were microscopically confirmed in keeping with national malaria guidelines. However, no quality control for used RDTs was conducted. Also, being a crosssectional survey, malaria burden reportedcouldnotreflectseasonalmalariatrendsandprospectivemalariaincidencerisk.apart from the study limitations reported above, this study showed that having malaria among HC attendeeswassignificantlypredictiveoffindingatleastonemalariainfectedcaseamonghis/her HHmembers(OR=2.3,Pvalue0.001)suggestingthatHCbasedpassivecaseidentificationcan beafeasibleentrypointforidentifyingcommunityhotspotsofmalariainfection. Guidelines on how to manage asymptomatic and minimally symptomatic RDT positive cases identifiedthroughactivecasedetectionarelackingandwouldberequiredintheeventthatcircle surveillanceisimplementedinthefuture.thecurrentlyrecommendedfirstlinetreatmentfor uncomplicatedmalariainrwandaisartemether Lumefantrine(AL).ALhasantigametocidal effectsandanabilitytoreduceasexualparasitaemialevelsandinfectivityamongmalariainfected individuals[35,36,37].itisplausiblethatalcan beusedamongasymptomaticand minimally symptomaticcasestoclearlocalreservoirpoolsandreducetheirmalariatransmissionpotential. SignificantspatialclusteringforHHcases(butnotHCcases)withtheclusterslocatednearwater basedagroecosystemsisaninterestingfinding.thebiggercluster(radiusof5km)isneighboring marshlandswheretraditionalricecultivationisdone(northeast),whilethesmallercluster(0.5 km radius) is located between multiple water streams and Lake Cyohoha in the south where MalariaduringpregnancyinRwanda 39

19 vegetableandotheragriculturecropsaregrown.wespeculatethatthesewateragroecosystems mayprovidesignificantreservoirsformosquitobreedingandhenceincreasedvectorintensityfor malariatransmission.thisfindingsuggeststhatfuturemalariacontroleffortsshouldconsider targeting potential breeding sites and engaging farming communities. To this end, an entomologicalevaluationofmosquitobreedingcapacityandendemicitymayguideintroduction ofintegratedvectormanagementpracticeswhilecommunitybasedenvironmentalmanagement approachesformalariacontrol,asshowntobeeffectiveinsettingscomparabletoruhuha,may be two potential effective area relevant strategies to employ [32]. To achieve malaria preeliminationstatusinruhuha,thebednetandirsstrategies,whichareprincipallyused,may needtobecomplimentedbyinterventionsthattargetareabreedingsitesandmalariariskfactors identifiedthroughspatialclusteringtechniqueaswasdonesinthisstudymayberequired[12]. Conclusion Inthisstudy,HCmalariaconfirmedcasesweresignificantlyassociatedwithfindingatleastone malariainfectedcaseamongtheirhhmembers.reactivecasefinding,bylinkinghcidentified passivecasestoactivelyidentifiedhhmalariainfection,isapotentiallypowerfulsurveillance system for identifying HHs with significant malaria risk and detecting asymptomatic carriers. Especiallyinlowtransmissionsettings,identifyingandtreatingasymptomaticcarriersiskeyin interruptingtransmission.therefore,circlesurveillance,whencombinedwithknowledgeonthe individual, the HH and the environmental malaria risk factors in a given community, can aid detectionofhotspotsandinformuseoftargetedmalariacontrolstrategies. MalariaduringpregnancyinRwanda 40

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