BioMed166dd.com

LETTERTOTHEEDITOROpenAccessTemperature,relativehumidityandsunshinemaybetheeffectivepredictorsforoccurrenceofmalariainGuangzhou,southernChina,2006–2012TiegangLi,ZhicongYangandMingWang*AbstractMalariahasbeenendemicinGuangzhouformorethan50years.
Thegoalofthisstudywastouseanegativebinomialregressiontoidentifytherelationshipbetweenmeteorologicalvariablesandmalariareported.
Ourresultsrevealedthateach1°Criseoftemperaturecorrespondstoanincreaseof0.
90%inthemonthlynumberofmalariacases.
Likewise,aonepercentriseinrelativehumidityledtoanincreaseof3.
99%andaonehourriseinsunshineledtoanincreaseof0.
68%inthemonthlynumberofcases.
Ourfindingsmaybeusefulfordevelopingasimple,precisemalariaearlywarningsystem.
Keywords:Malaria,Parasitedisease,Meteorologicalvariables,Correlation,EarlywarningLettertotheeditorMalariaisaprotozoandiseasecausedbyparasitesofthegenusPlasmodium.
Itisoneoftheleadingcausesofillnessanddeathintheworld[1],thevastmajorityofcasesareinAfricaandSouth-EastAsia[2].
AsthelargesttradingcityinsouthernChina,Guangzhouhasover7.
94millionregisteredinhabitantsanda4.
76millionfloatingpopulation(from2010censusdata)[3],heremalariahasbeenendemicformorethanhalfacentury[4],andpublichealthauthoritiesareconcernedaboutitshighprevalence.
In2009,ChinalaunchedaMalariaEliminationActionPlan(MEAP)for2010–2020[5].
Despitevariouspreven-tionandinterventionstrategiesthatareimplementedandenhancedbythegovernment,theincidenceofmal-ariastillshowedanincreasingtrendinGuangzhou.
In2012,atotalof112malariaconfirmedcaseswerereported,whichismorethantwicethenumberreportedin2009(53cases).
Malariacontrolisabigchallengeduetomanyfactors.
Oneofthecriticalprogramstopreventthisdiseaseconcentratedonmonitoringandpredictingmalariaincidence.
Previousstudieshaveshownthatweatherfactorshadsignificantcorrelationwithmalaria[6-8].
However,duetothedifferenceingeographicalandclimatecharacteristics,meteorologicalvariablesinfluencemalariaincidenceindifferentareasindifferentways[9].
Moreover,inmostrecentyears,reportsregard-ingmeteorologicalvariablesaspredictorsfortheoccur-renceofmalariainsouthernChinaarefairlylimited.
Inthisstudy,weaimtoexaminetheeffectofweathervari-abilityontheincidenceofmalariainthesubtropicalcityofGuangzhoufortheperiodof2006–2012,andassistpublichealthpreventionandcontrolmeasures.
MethodsInChina,malariaisanotifiableClass-Bcommunicabledisease,andallcasesofmalariawerediagnosedaccordingtotheunifieddiagnosticcriteriaissuedbyTheChineseMinistryofHealth.
PhysicianswhodiagnosesuspectedorconfirmedmalariacasesmustreportthesecasestoGuangzhouCentersforDiseaseControlandPrevention(GZCDC)throughtheNationalNotifiableDiseaseReportSystem(NNDRS).
Weobtainedthelaboratoryconfirmedcasesduringtheperiodof2006to2012fromNNDRS,andsimultaneousmeteorologicaldata,includingdailyaveragetemperature(indegreesCentigrade),relativehu-midity(asapercentage),atmosphericpressure(inhPa),andwindvelocity(inmeterspersecond)wereobtainedfromthedocumentationoftheGuangzhouMeteoro-logicalBureau(GZMB).
Anegativebinomialregressionwasusedtoidentifytherelationshipbetweenmeteoro-logicalvariablesandmalaria.
Thecasesaretheprevalence*Correspondence:wangming@gzcdc.
org.
cnGuangzhouCenterforDiseaseControlandPrevention,Guangzhou,GuangdongProvince510440,China2013Lietal.
;licenseeBioMedCentralLtd.
ThisisanOpenAccessarticledistributedunderthetermsoftheCreativeCommonsAttributionLicense(http://creativecommons.
org/licenses/by/2.
0),whichpermitsunrestricteduse,distribution,andreproductioninanymedium,providedtheoriginalworkisproperlycited.
Lietal.
Parasites&Vectors2013,6:155http://www.
parasitesandvectors.
com/content/6/1/155ofmalariaper100000inhabitantsgroupedbymonthofonsetandforeachmeteorologicalvariable,amonthlyaverageoraggregatewascalculated.
ApreliminaryanalysiswasconductedthroughPearson'scorrelationcoefficient('r')matrixwithinme-teorologicalvariables.
Thisindicatedthatthemodelconstructedusingcontemporaneouslybothtemperatureandatmosphericpressuresufferedfromcollinearityproblems,becausethetwovariablesshowedstrongnegativecorrelation(r=0.
86,P65was0.
36%,3.
57%,71.
07%,21.
96%,and3.
047%,respectively.
Ofthosesixmeteorologicalvariablesstudied,tem-perature,relativehumidityandsunshinewerestatisti-callysignificantinthefinalmodel.
Each1°Criseoftemperaturecorrespondstoanincreaseof0.
90%(95%CI0.
60%to1.
10%)inthemonthlynumberofmalariacases.
Likewise,aonepercentriseofrelativehumidityledtoanincreaseof3.
99%(95%CI2.
53%to5.
48%)andaonehourriseinmonthlydurationofsunshineledtoanincreaseby0.
68(95%CI0.
47%to0.
88%)inthemonthlynumberofcases(Table2).
DiscussionandcommentWeatherfactorssuchtemperature,humidity,etal.
havebeenprovedtohavesignificantinfluenceonoccurrenceandtransmissionofsomeinfectiousdiseases.
Forexample,inSwitzerland,higherwatervaporpressureandheatwerefoundassociatedwithahigherriskofcommunity-acquiredLegionnaires'disease[10];inBotswana,theelevationofannualminimumtemperaturewasconsideredasthecriticalfactorforcontinuousascentinthenumberofdiarrhealdiseasereportedduringtheperiodof1974–2003[11].
TheresultofcurrentstudyshowedthattemperaturewaspositivelyassociatedwithmalariaincidenceinGuangzhouarea.
Thisfindingisingeneralagreementwithotherstudies[12]inwhichtemperatureisconsideredtobeaprecipitatingfactorfordistributionofAnopheles,thetransmissionvectorofmalaria.
Wefoundrelativehumiditywaspositivelyassoci-atedwithmalariaincidenceofthesamemonth.
SimilarobservationwasalsoreportedinCameroonwheremoreAnophelesmosquitoesespeciallyAnophelesgambiaewerecollectedduringtherainyseasoncomparedtothedrysea-son[13,14].
InconsistentwiththestudyfromKorea[13],wefounddurationofsunshinewaspositivelyassociatedwithmalariaincidence.
However,thisfindingaccordswithDiegoAyala'sfindingswhichshowedmalariavectorsoc-currenceswerepositivelycorrelatedtoincreasingsunlightexposure[15].
Furtherstudies,whichtakethesevariablesintoaccount,willneedtobeundertaken.
Takentogether,wehavereportedthatweatherfactorshadsignificantinfluenceonoccurrenceandtransmissionofmalariainGuangzhou,southernChina.
Ariseintemperature,relativehumidityanddurationofsunshinemayincreasetheriskofmalariainfection.
Ourfindingprovidespreliminarybutfundamentalinformationthatmaybeusefultodevelopasimple,precise,andlowcostfunctionalmalariaearlywarningsystem.
CompetinginterestsTheauthorsdeclarenofinancial,academicorintellectualcompetinginterests.
Authors'contributionsConceivedanddesignedthestudy:ZhicongYang,MingWang.
Analyzedthedata:TiegangLi.
Contributedmaterials/analysistools:ZhicongYang,MingWang.
Wrotethepaper:TiegangLi,ZhicongYang,MingWang.
Allauthorscontributedtoandapprovedthefinalversionofthemanuscript.
Authors'informationTheauthorsareallepidemiologistsinGuangzhoucenterfordiseasecontrolandprevention(GZCDC).
Theauthorsregularlyconductthesurveillanceoninfectiousdisease,filedinvestigationonoutbreaks,emergentmanagementonpublichealthcrisis,andresearchonriskfactorsandtransmissionofdiseases.
AcknowledgementsAllenrolleeswhoparticipatedinthestudyareappreciated.
WewishtogivespecialthankstothepublicunitcoordinatorsandnursesinhospitalsinGuangzhou.
Received:17May2013Accepted:27May2013Published:30May2013References1.
AbebeA,DagnachewM,MikrieM,MeazaA,MelkamuG:TenyeartrendanalysisofmalariaprevalenceinKolaDiba,NorthGondar,NorthwestEthiopia.
ParasitVectors2012,5:173.
2.
SnowRW,GuerraCA,NoorAM,MyintHY,HaySI:TheglobaldistributionofclinicalepisodesofPlasmodiumfalciparummalaria.
Nature2005,434:214–217.
3.
LiT,FuC,DiB,WuJ,YangZ,WangY,LiM,LuJ,ChenY,LuE,GengJ,HuW,DongZ,LiMF,ZhengBJ,CaoKY,WangM:Atwo-yearsurveillanceof2009pandemicinfluenzaA(H1N1)inGuangzhou,China:frompandemictoseasonalinfluenzaPLoSOne2011,6:e28027.
4.
ZhouSS,WangY,LiY:[MalariasituationinthePeople'sRepublicofChinain2010](inChinese).
ZhongguoJiShengChongXueYuJiShengChongBingZaZhi2011,29:401–403.
5.
XuJ,LiuH:ThechallengesofmalariaeliminationinYunnanProvince,People'sRepublicofChina.
SoutheastAsianJTropMedPublicHealth2012,43:819–824.
6.
BaptistaJL,WéryM,vanderStuyftP:Influenceofstoragetemperatureonestimatesoftumournecrosisfactorinplasmasamplesfrompatientswithcerebralmalaria.
AnnTropMedParasitol1997,91:429–431.
7.
LohaE,LindtjrnB:ModelvariationsinpredictingincidenceofPlasmodiumfalciparummalariausing1998–2007morbidityandmeteorologicaldatafromsouthEthiopia.
MalariaJ2010,9:166.
8.
BombliesA,EltahirEA:AssessmentoftheimpactofclimateshiftsonmalariatransmissionintheSahel.
EcoHealth2009,6:426–437.
9.
NathDC,MwchaharyDD:Associationbetweenclimaticvariablesandmalariaincidence:astudyinKokrajhardistrictofAssam,India.
GlobJHealthSci2012,5:90–106.
10.
ConzaL,CasatiS,LimoniC,GaiaV:Meteorologicalfactorsandriskofcommunity-acquiredLegionnaires'diseaseinSwitzerland:anepidemiologicalstudy.
BMJOpen2013,3:e002428.
11.
AlexanderKA,CarzolioM,GoodinD,VanceE:ClimatechangeislikelytoworsenthepublichealththreatofdiarrhealdiseaseinBotswana.
IntJEnvironResPublicHealth2013,10:1202–1230.
12.
ValérieO,MarcD,PierreD,MarcC:AnophelesspeciesassociationsinSoutheastAsia:indicatorspeciesandenvironmentalinfluences.
ParasitVectors2013,6:136.
Lietal.
Parasites&Vectors2013,6:155Page3of4http://www.
parasitesandvectors.
com/content/6/1/15513.
Antonio-NkondjioC,Awono-AmbeneP,FontenilleD,NgassamP,SimardF,TchuinkamT,TotoJC:MalariavectorsandurbanizationintheequatorialforestregionofsouthCameroon.
TransRoySocTropMedHyg2005,5:347–354.
14.
BigogaJD,NanfackFM,Awono-AmbenePH,SalomonP,JeanA,OtiaVS,EtienneF,MoyouRS,RoseGFL:SeasonalprevalenceofmalariavectorsandentomologicalinoculationratesintherubbercultivatedareaofNiete,SouthRegionofCameroon.
ParasitVectors2013,6:136.
15.
DiegoA,CarloC,KenjiO,KamdemGC,ChristopheA-N,Jean-PierreA,ParfaitA-A,DidierF,FrédéricS:HabitatsuitabilityandecologicalnicheprofileofmajormalariavectorsinCameroon.
MalariaJ2009,8:307.
doi:10.
1186/1756-3305-6-155Citethisarticleas:Lietal.
:Temperature,relativehumidityandsunshinemaybetheeffectivepredictorsforoccurrenceofmalariainGuangzhou,southernChina,2006–2012.
Parasites&Vectors20136:155.
SubmityournextmanuscripttoBioMedCentralandtakefulladvantageof:ConvenientonlinesubmissionThoroughpeerreviewNospaceconstraintsorcolorgurechargesImmediatepublicationonacceptanceInclusioninPubMed,CAS,ScopusandGoogleScholarResearchwhichisfreelyavailableforredistributionSubmityourmanuscriptatwww.
biomedcentral.
com/submitLietal.
Parasites&Vectors2013,6:155Page4of4http://www.
parasitesandvectors.
com/content/6/1/155