rev bras hematol hemoter. 2016;38(1):90–91
w w w . r b h h . o r g
Revista
Brasileira
de
Hematologia
e
Hemoterapia
Brazilian
Journal
of
Hematology
and
Hemotherapy
Letter
to
the
Editor
Zika
virus
and
its
implication
in
transfusion
safety
Zikavirus(ZIKV),anemergingflavivirus,wasinitiallyisolated in1947fromaRhesusmonkeyinUganda.Thefirstevidence ofhumantransmissionofZIKVwasreportedin1952.1Only
sporadiccasesofZIKVinhumanswerereportedinAfricaand Asiabefore2007,whensignificantoutbreakswereregistered outsidetheseregions–ontheislandsofMicronesia,French PolynesiaandNewCaledoniainthePacificOcean.2InBrazil,
thefirst autochthonousZIKVtransmissionwasreported in thenortheasternregioninMay2015.3ItisbelievedthatZIKV
wasintroduced inBrazil byasymptomatic travelers during the 2014World Cup or bythe World Sprint Championship canoerace.4,5ZIKVhassimilarcharacteristicstoDenguevirus
in relation to epidemiology and the transmission cycle in urbanenvironments.6Therefore,weshouldexpectthat,due
tothelargedistributionofthearthropodvectors(Aedesaegypti
mosquitoes),thenumberofoutbreaksandsymptomaticcases mightpropagate.
InBrazil,thereare 17officiallyconfirmed ZIKVcasesin three states: Bahia, Rio Grande do Norte and São Paulo.7
However,withthespreadofZIKVinthecountry,theWorld HealthOrganization(WHO)hasalreadyreportedZIKVin14 Brazilianstatesincluding Alagoas,Bahia, Ceará,Maranhão, MatoGrosso, Pará,Paraíba, Paraná, Pernambuco, Piauí, Rio de Janeiro,Rio Grandedo Norte,Roraima, and São Paulo.8
Currently, Brazil is evidencing a high number of cases of microcephaly,mainlyinthenortheasternpartofthecountry, whichwasbelievedtobelinkedtoZIKVinfectionacquired during pregnancy. However, this cannot be confirmed due toinsufficientscientificsupportasZIKVRNAwasfoundin the amniotic fluid of only two cases. If this condition is foundtoberelated toZIKV,it willrepresenta novel clini-calmanifestationofthisemergingvirus.Otherneurological disorderscorrelatedtoZIKVmanifestationsinclude: Guillain-Barrésyndrome,encephalitis,myelitis,meningoencephalitis, andopticalneuritis.9
SinceZIKVisanblood-bornevirustransmittedby arthro-pods, it represents potential risk for transfusion safety. Althoughthe significanceofZIKVtothe blood transfusion processand useofbloodderivatives iscurrentlyunknown, thereisariskthatZIKVcouldalsobetransmittedby trans-fusions.Ahighnumberofasymptomaticblood donorswas observedduringtheFrenchPolynesiaoutbreak.However, sev-eralquestionsremainunclearrelatedtothepossibleimpact
of ZIKV in blood transfusion and transfusion medicine in general:
1. ThepotentialofZIKVtocauseasymptomaticcasesmustbe
elu-cidated.AsymptomaticcasesofZIKVamongblooddonors
(up to74%) havebeen reported.10 Therefore, the
poten-tialoftransmissionbytransfusionexits.Tocalculatethe transfusion-transmission model, it is importantto esti-matetheincidenceofinfectionandtheaverageduration ofviremia.11However,evenatagloballevel,thereisno
informationabouttheincidenceofinfectioninthegeneral populationandtheeventsrelatedtotheviremicphaseof ZIKVinfection.
2. ViralloadofZIKVinfection.ViralloadduringZIKVinfection
haspreviouslybeenmeasuredinbloodsamplesof asymp-tomaticblooddonors(3.40–6.91logcopies/mL).12
Addition-ally,viralloadhasbeendetectedinurine10to20daysafter theonsetofthedisease(0.7–220×106copies/mL).13
There-fore, transfusion-transmitted ZIKV infection is possible. However,moredetailed studiesconcerningthe quantity andviremiaperiodinasymptomaticindividualsare essen-tial.
3. Effectivenessoftransmissionviabloodtransfusion.Untilnow,
theeffectivenessofthetransmissionofZIKVvia transfu-sionofbloodisunknown. Asotherflaviviruses,suchas Denguevirus1–4andWestNilevirus,11canbe
transmit-tedbybloodtransfusionandcauseclinicalsymptomsin blood recipients,14 the transmissionofZIKVby
transfu-sionsseemspossible.
4. InactivationofZIKVinblood.ItseemsthatZIKVissensitive
tobloodpathogeninactivationprocedures.Theapplication ofamotosalenandultravioletAilluminationreducesviral titersinplasmaandZIKVdoesnotproductivelyinfectcell cultures.Inaddition,bythesecondpassageincellcultures, ZIKVRNAbecomesundetectable.15 Therefore,the
proce-duresofpathogeninactivationinbloodseemtobeeffective to inactivate ZIKV and prevent transfusion-transmitted infection.
5. MoleculardiagnosisofZIKVduringscreeningforblooddonation.
rev bras hematol hemoter. 2016;38(1):90–91
91
reactionsystemsinReferenceLaboratories.The immedi-ateimplantationofmolecularteststoscreenblooddonors at this moment seems unfeasible. This isnot onlydue tothehighcostofmoleculartestingbutalsotothefact thatthepathogenesisofZIKVinfectionisnotfully under-stood.Moreover,ZIKVinfectionisseasonalasmorecases are reported duringthe peak proliferation periodofthe transmittingarthropodvectors,thereforethe implemen-tationofblooddonorscreeningforZIKVshouldfollowthe seasonalityofinfection.
6. Conductanddeferralofblooddonorsfromdonation.Brazilian
blood banksshouldintensifythepre-donationscreening tominimizetheriskofthetransmissionofZIKVby trans-fusions.Itisimportanttopayattentiontopossibledisease riskfactors(signsandsymptomsofanarboviraldisease, traveltoendemicareas,etc.)inblooddonorcandidates.We alsorecommendthatbloodbanksoffereducational pro-gramsaboutZIKVinfectiontoalertaboutthepotentialrisk ofthetransmissionofthisemergingvirus.
Conclusion
ZIKVisanemergingvirusinBrazil.Inthemajorityofcases, theinfectionisasymptomatichowevermildtosevere clini-calsymptomshavealsobeendescribed.Theefficiencyofthe transmissionofZIKV bytransfusions isstillunknown and additionalstudiesareneededtobetterevaluatetheproportion ofasymptomaticblooddonorsinfectedbyZIKV,theduration ofviremiabefore clinical signsof acutearboviral infection appear,andtheclinicaloutcomesofZIKVinfection.Untilnow, theonlypreventivemeasurestocontrolZIKVinfection are stringentvectorcontrolandindividualprecautionsinrespect tomosquitobites.
Conflicts
of
interest
Theauthorsdeclarenoconflictsofinterest.
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Dupont-RouzeyrolM.DetectionofZikavirusinurine.Emerg InfectDis.2015;21(1):84–6.
14.LeviJE,NishiyaA,FélixAC,SallesNA,SampaioLR,HangaiF, etal.Real-timesymptomaticcaseoftransfusion-transmitted dengue.Transfusion.2015;55(5):961–4.
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SimoneKashima∗,SvetoslavNanevSlavov, DimasTadeuCovas
UniversidadedeSãoPaulo(USP),RibeirãoPreto,SP,Brazil
∗Corresponding author at: Laboratório de Biologia Molecular,
Fundac¸ãoHemocentrodeRibeirãoPreto,RuaTenenteCatão Roxo,2501,14051-140RibeirãoPreto,SP,Brazil.
E-mailaddress:[email protected] (S.Kashima).
Received18December2015 Accepted6January2016 Availableonline4February2016
http://dx.doi.org/10.1016/j.bjhh.2016.01.002
