Climate factors and dengue fever occurrence in Makassar during period of 2011–2017

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Keywords:

Dengue Humidity Rainfall Temperature Windspeed

Methods:ItwasquantitativestudylocatedinMakassar.DatawereanalyzedbyGeneralEstimatingEqua- tion(GEE).Geewasusedtoshowingthemodelofvariables.ThisstudyusedsecondarydatafromHealth DistrictOfﬁceofMakassartogetDengueCasesDataandMeteorological,Climatological,andGeophysical AgencyofMakassarformonthlyclimatedata.

Results:Theresultshowedsigniﬁcantcorrelationbetweenclimatevariablesthathavebeenresearched whichweretemperature,humidity,rainfall,andwindspeedtodenguefevercases.

Conclusions:Asconclusion,thehumidityhadstrongestcorrelationtodenguefevercases.Italsoshowed positivecorrelation,whileothersshowednegativecorrelation.

Introduction

Denguefeverisavector-bornediseasethathasgrowndramati- callyinincidenceratesaroundtheworldinrecentyears.Theagent ofdenguefeverisadenguevirus.Denguetransmissionhasheight- enedsigniﬁcantlyinmosttropicalcountries.¹In2017,thenumber ofdenguecasesinIndonesiawas68,407.WhileSouthSulawesiwas onthethirteenthprovincewithahighnumberofdenguecases.²

Amosquitoasavectorofdiseaseisextremelysensitivetoitssur- roundingsspeciﬁcallyclimateconditions.³Anepidemicofdengue occurs during thehumid, warm, and rainy period, which sup- portsthegrowthofmosquitoanddiminishtheextrinsicincubation period.⁴AccordingtoTheHealthDistrictOfﬁce(2004),Thedengue fevervectorwillsurviveintemperature28–32^◦C.Besidestem- perature,humidityalsowilldeterminethemosquitolifethrough thedeterminationofthedurabilityofthetracheaintorespiratory mosquitoes.⁵Therefore,thestudyaboutclimatefactorslinkedto denguefeverwasconductedtoknowtherelationshipofbothvari- ables.

Methods

ThisstudywaslocatedinMakassarbecausedenguefeverwas still being a problem with a ﬂuctuating number of cases. This studywasquantitativewithadescriptiveanalysisusingecological

夽Peer-reviewunderresponsibilityofthescientiﬁccommitteeofthe3rdInter- nationalNursing,HealthScienceStudents&HealthCareProfessionalsConference.

Full-textandthecontentofitisunderresponsibilityofauthorsofthearticle.

∗ Correspondingauthor.

E-mailaddresses:[email protected],[email protected] (S.Basri).

designstudyofclimatefactorsanddenguefever.Theclimatefac- torsvariableweretemperature,humidity,rainfall,andwindspeed asindependentvariables.Whiledenguefevercasesbecamedepen- dentvariables.Thisstudyusedsecondarydata.Themonthlycases wereobtainedfromtheHealthOfﬁceofMakassar.Besides,monthly temperature,humidity,rainfall,andwindspeedweregainedfrom Meteorological,Climatological,andGeophysicalAgencyofMakas- sar.

Dataanalyzedusingunivariateandbivariateanalysisbystatisti- caldataapplication.DatawereanalyzedbyGeneralizedEstimating Equation (GEE)for multivariateanalysis todeterminetherela- tionshipbetweendenguecasesandclimatevariables.Itwasused becausethisstudywasinlongitudinalresearch.Thelongitudinal studywascomprisedofrepeatedorcontinuousmeasurestofollow casesoveralongperiodinyearsordecades.⁶

Result

ThenumberofcasesinMakassarfrom2011to2017showed diversemodels.Thehighestcasesin2011–2012wereinJanuary andFebruary.Thedescriptionofdenguefeverdiseasewasdepicted inFig.1.Meanwhile,thelowest numberof casesineveryyear almostshowedthesamemodels,ithappenedfromOctoberuntil December.

Accordingtodescriptiveanalysis(Table1),theaveragenumber ofcaseswas13cases.Thelowestwastwocasesandthehighest was62cases.Whereas,theaveragetemperatureinMakassarin 2011–2017was27.87^◦C.Thelowesttemperaturewas26.6^◦Cand thehighesttemperaturewas29.4^◦C.Whiletheaveragehumidity was80.01%RHwith66.77%RHasthelowesthumidityand89.60as thehighestone.

Besidestemperatureandhumidity,therewasrainfallandwind speedthatwasanalyzed.TheaveragerainfallinMakassarfrom

https://doi.org/10.1016/j.gaceta.2021.10.063

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Fig.1. DenguefevercasesinMakassar2011–2017.Source:HealthOfﬁceofMakassar.

Table1

DescriptivedistributionofcasesandclimatefactorsinMakassar2011–2017.

Variables Mean Standarderror Standarddeviation Min–Max

Denguefevercases 13 1.32 12 2–62

Temperature 27.87 0.07 0.68 26.6–29.4

Humidity 80.01 0.68 6.27 66.77–89.60

Rainfall 13.89 1.19 10.96 0–43.4

Windspeed 2.24 0.05 0.43 1.35–3.62

Fig.2. CorrelationbetweentemperatureandcasesinMakassar2011–2017.Source:Meteorological,Climatological,andGeophysicalAgencyofMakassarandHealthOfﬁce ofMakassar.

2011 to2017 was 13.89mm with0mm as the lowest rainfall and43.4mmasthehighestone.For thewindspeed, themini- mumspeedwas1.35km/handthemaximumwas3.63km/hwith 2.24km/hastheaveragespeed.

ThetemperatureinMakassar2011–2017wasﬂuctuatingevery monthinayear.Thehighestcasewasin27.34^◦CinJuly2013and thelowestcaseshappenedinthreesametimesthatwereinOcto- ber2012(29.1^◦C),December 2012(28^◦C),and December2016 (27.5^◦C)(Fig.2).

Humiditywasoneoftheclimatefactorsthatwasexaminedin thisstudy.HumidityinMakassarwasﬂuctuatingbutnotinthe widerange.Thehighestcasewasin75.94%RHinJuly2013.While, thelowestcaseswerein74%RH(October2012),82.2%RH(Decem- ber2012),and85.9%RH(December2016)(Fig.3).

Besidestemperatureandhumidity,rainfallwasalsothecause oftherisingnumberofdenguecases.RainfallinMakassarfrom

2011to2017wasinthemediumcategory.Thehighestdengue fevercasewasin1mminJuly2013andthelowestcaseswerein 3.2mm(October2011),20.2mm(December2011),and23.3mm (December2016)(Fig.4).

Windspeed can inﬂuence thedistribution ofdengue vector whichwasAedesaegypti.Thehighestdenguecasewasin2.16km/h in July 2013.While the lowest cases were 2.61km/h (October 2013),2.84km/h(December2013),and3.5km/h(December2016) (Fig.5).

The result of the correlation between temperature, rainfall, humidity, and wind speed showed a significant correlation to dengue fever cases as long as 2011–2017 in Makassar. Gen- eralized estimating equation (GEE) resulted that all climate factors had a significant correlation to dengue fever cases (p-value<0.05). Although the temperature had p-value >0.05, substantially, the temperature had a significant correlation to

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Fig.4.CorrelationbetweenrainfallvariableandcasesinMakassar2011–2017.Source:Meteorological,Climatological,andGeophysicalAgencyofMakassarandHealth OfﬁceofMakassar.

Fig.5. CorrelationbetweenwindspeedanddenguefevercasesinMakassar2011–2017.Source:Meteorological,Climatological,andGeophysicalAgencyofMakassarand HealthOfﬁceofMakassar.

dengue fever cases. Besides the value of probability number was higher than the chi-square value with 0.0001 (signiﬁ- cant).

Oneclimatevariablehadapositivecorrelationwiththecases whichwerehumidityvariables.Whiletemperature,rainfall,and windspeedhad negativecorrelations.Thedominantfactorwas

the humidity.GEE analysis showed a model of thecorrelation between climate factors and cases. But the model was only ﬁt if the value of temperature was26.6–29.4^◦C humidity was 66.7667%RH–89.6%RH;rainfallwas0–43.4mm;windspeed was 1.35–3.62069km/h.Theinformationabouttestresultwasserved inTable2.

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Table2

ThecorrelationofclimatevariablesanddenguecasesinMakassar2011–2017viageneralizedestimatingequation(GEE).

Variables Coefﬁcient Standarderror p-value 95%conﬁdenceinterval(CI)

Temperature −3.027779 1.71 0.076 −6.37–0.31

Humidity 1.331466 0.266 0.0001 0.81–1.85

Rainfall −0.5191256 0.156 0.001 0–0.821–(−0.21)

Windspeed −8.493344 2.55 0.001 −13.50–(−3.48)

Constant 17.20698 56.86 0.762 −94.24–128.66

Note:Prob>chi2=0.00001.

Dengue fevercases=17.20698+1.331466* Humidity−0.51912563*Rainfall−3.027779* Temperature−8.493344*WindSpeed.

Discussion

Denguefeverisfast-spreadingvector-bornediseases.Dengue cases increase distinctly possible throughout rainy time and becameWHOalerts.⁷Itwasfollowingtheresultofthisstudythat mostly,thehighestcaseseveryyearfrom2011to2017happened inJanuaryandFebruary.SinceJanuaryandFebruarywasarainy season.WhilethelowestcaseshappenedfromOctober–December sinceOctoberandNovemberwerethedryseasons.

Severalstudiesalsohadasignificantcorrelationofseveralcli- matevariablestodenguecases.Colón-Gonzálezetal.⁸statedthat weatherwhichwastemperaturesignificantlyinfluenceddengue caseincidenceinMexico.Asmentioned,thetemperaturehad a remarkablecorrelation todengue fever cases.⁹ The studyfrom Tuladharetal.(2019)identifiedthattemperaturebecameapoten- tialcontributortotheprevalenceofdengueinNepal.Theconducive temperatureforvectorsurvivalwasbetween23and25^◦C.¹⁰Sim- ilartothestudyfromLai¹¹thatalsofoundthattemperaturewas remarkablyrelatedtotheincidenceofdengue.Theincreaseintem- peraturewasfollowedbytheincreaseofcasestransmissionrate.

Thecorrelationbetweentemperatureanddenguecaseswasnega- tive.Temperatureinﬂuencedtheincreasingnumberofcaseswhen theaveragetemperaturedecreased,thenumberofreportedcases increased.¹²

Thehumidityhadastrongcorrelationcomparedtoothers.It wasfollowingthepreviousstudythatstatedthathumiditywas determinantsindenguefeverincidenceandoutbreak.^13,14Humid- itywasalsohasastableimpactondenguecasesthantemperature asthetimewhenitwasconsideredthevirologicalmatters.¹⁵Fur- thermore,relativehumiditymaybeafactorthatdecisivelyaffects theeggdevelopmentandadultpopulationnumberofA.aegypti thatmayitselfbeassociatedwithvectorialcapacity.¹⁶

Themainvariablethatinﬂuencestodenguecasesincidenceis rainfall.AsmentionedinthestudyofGotoetal.¹⁷therainfallvari- ablewasslightlyinﬂuenceddenguefevercasesinColomboand Anuradhapura.SimilartoChienandYu¹⁸thatfoundrainfallwas themostremarkablefactorwiththecasesinSouthTaiwan.

ThestudythatwasconductedbySantosetal.(2019)showed thatthe90daysrainfallshowedthemostsigniﬁcantcorrelation withthecases.¹⁹ThisstudyshowedthatDecember becamethe timethatthecasesdecrease.Eventhough,Decemberistherainy season.Negativelinewasalsoshowninthecorrelationofboth rainfallandcases.

But,anotherpreviousstudyprovidedinformationthatthehigh- estcasesof denguewereonApril, whileApril isthetransition oftherainytodryseason.²⁰ Ithappenedbecauserainfallcould causetherisingofthetransmissionofA.aegyptibyprovidingor eveneliminatingthebreedingsitethroughﬂoodingthevector.²¹ Thespreadingofthevectoralsohappenedinthedryseasonwhen waterstoragecontainerswerestillavailable.²²Heavyrainfallpro- ducedmanyoutdoorbreedingsourcesforAedes,butdrycausedan

increaseinwaterstoragecontainerswhichcanbecomethebreed- inghabitats.²³

Windspeedvariableinthisresearchalsohadasignificantcor- relationtodenguefevercases.Itwasinlinewiththeresearchfrom Nashuha(2018)thatwindspeedinfluencedtheimpactofdengue transmission,especiallyinhighpopulationdensityintheStateof Perak.²⁴Althoughthisstudyshowedasignificantcorrelation,the windspeedhadanegativecorrelationtodenguefevercases.The studythatwasconductedbyCheongetal^.25wasalsofoundaneg- ativecorrelationbetweenwindspeedandthecases.Windspeed variablerepresentedadistinctcorrelationwithdenguecases,from thegeneralnegativecorrelationinBarbadosaswell.²⁶Strongwinds canreducemosquitodensityso,themosquitowillbedifficultto findahost.²⁷

Beyondtheresultofthisstudy,itstillhasalimitation.Thelim- itationofthisstudyincludedthelackofrangecasesandclimate data.Whiletogetabetterresult,astudyshouldbeheldforten yearsoftheperiod.

Conclusion

In conclusion, the dengue fever cases in Makassar over the pastsevenyearstendtovaryaccordingtotheseason.Allclimate variables(humidity,rainfall,temperatureandwindspeed)inthis studyhadasigniﬁcantcorrelationtodenguefevercasesinMakas- sar.Whilehumiditytookadominantcorrelationtodenguefever casescompared tootherclimatefactors.Somepreventivemea- surestodealwithweredenguefevermustbeintroducedtothe localcommunities,sotheirknowledgeaboutthetransmissionand eliminationofdenguefevercanincrease.Healthofﬁcerscanalso helpdisseminateknowledgebyprovidinginformationaboutvec- torcontrol,especiallyintherainyseason.Thus,thetransmission ofdenguefeverthroughmosquitoescanbereduced.

Ethicalconsiderations

Theethicalclearancewasrecognizedbytheethicalcommittee fromKEPKFKIKUniversitasIslamNegeriAlauddinMakassarwhich registeredinnumberA.055/KEPK/FKIK/I/2019.

Conﬂictofinterest

Thisresearchhadnoconﬂictofinterest.

Acknowledgments

TheauthorsthankMeteorological,Climatological,andGeophys- icalAgencyofMakassarandHealthOfﬁcein Makassarthathas providedsecondarydatathatwereneededbytheauthorstomake thismanuscript.

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