Low seroprevalence of Zika virus in Cameroonian blood donors

brazjinfectdis2017;21(4):481–483

w w w . e l s e v i e r . c o m / l o c a t e / b j i d

The

Brazilian

Journal

of

INFECTIOUS

DISEASES

Brief

communication

Low

seroprevalence

of

Zika

virus

in

Cameroonian

blood

donors

Bouba

Gake

_,

_Marie

_A.

_Vernet

_,

_Isabelle

_{Leparc-Goffart}

_,

_Jan

_Felix

_Drexler

_,

Ernest

A.

Gould

_,

_Pierre

_Gallian

_,

_Xavier

_de

_Lamballerie

a_{UMR“émergencedesPathologiesVirales”,Aix-MarseilleUniv,IRD190,INSERM1207,EHESP,Marseille,France} b_{CentrePasteurduCameroun,Yaoundé,Cameroon}

c_{NationalReferenceLaboratoryforArboviruses,InstitutdeRechercheBiomédicaledesArmées,Marseille,France} d_{UniversityofBonnMedicalCentreInstituteofVirology,Bonn,Germany}

e_{ÉtablissementFranc¸aisduSang,LaPlaineSaint-Denis,France}

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Articlehistory:

Received4March2017 Accepted16March2017 Availableonline23May2017

Keywords:

Zikavirus Seroprevalence Africa

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AZikavirusseroepidemiologystudywasperformedin1084blooddonorscollectedfrom August to October 2015 in six sites of Cameroon representing a large panel of eco-environments.Samplesweretestedusingananti-NS1IgGELISAdetectionkitandpositives werefurtherconfirmedbyseroneutralization.Theobservedglobalseroprevalencewaslow (around5%,peakingat10%and7.7%inDoualaandBertoua,respectively)withrisk fac-torsassociatedwithseropositivitypointingtotheexistenceofalocal(peri-)sylvaticcycle oftransmission.Theseresultscallattentiontothepotentialintroductionandsubsequent spreadinAfrican urbanareas ofAsiangenotypeZikaviruscurrentlycirculatinginthe Americasandadaptedtotransmissionbyperi-domesticmosquitoes.Theyshouldleverage reinforcedsurveillanceeffortsinAfrica.

©2017SociedadeBrasileiradeInfectologia.PublishedbyElsevierEditoraLtda.Thisisan openaccessarticleundertheCCBY-NC-NDlicense(http://creativecommons.org/licenses/ by-nc-nd/4.0/).

TheAsiangenotypeofZikavirus(ZIKV)hasbeen responsi-bleforrecentoutbreaksinthePacificislands,theCaribbean andSouth/CentralAmericawheresevereandformerly unde-scribedfetalandneurologicalcomplicationsofthedisease,1,2

aswellasnon-vectoredroutesoftransmission,3_havebeen

observed.Accordingtophylogeneticanalyses,theAsian geno-typeofZIKVemergedoutofAfrica∼180yearsago.4Astriking observationisthattherecentAsiangenotypePacificandNew

∗ _{Correspondingauthor.}

E-mailaddress:xavier.de-lamballerie@univ-amu.fr (X.deLamballerie).

World circulating ZIKVstrainsare adaptedtotransmission bythevectorAedesaegypti5_{andthatthisphenotypictraitis}

mostprobably crucialtounderstandtheir epidemic poten-tial.Bycontrast,ZIKVstrainsbelongingtotheoriginalAfrican genotypehaveneverbeenimplicatedinlargeoutbreaksand thevectorcompetenceofAfricanAedesaegyptiislow.6_Hence,

thereisconsiderableneedforimprovingourknowledgeabout theecologyandepidemiologyoftheAfricangenotypeandin particularestimatingtheherdimmunityofAfrican popula-tionsagainstZIKV.AlthoughhumancasesofZIKVinfection havebeenreportedinAfricasincetheearly1950s,thisbasic informationremainsessentiallyunavailable.

http://dx.doi.org/10.1016/j.bjid.2017.03.018

1413-8670/©2017SociedadeBrasileiradeInfectologia.PublishedbyElsevierEditoraLtda.ThisisanopenaccessarticleundertheCC BY-NC-NDlicense(http://creativecommons.org/licenses/by-nc-nd/4.0/).

482

Fig.1–SeroprevalenceofZikavirusinblooddonorsfromsixregionsofCameroon.

In this respect, 1084 blood donors from six sites of Cameroon representing a large panel of eco-environments wereenrolledinaZIKVseroepidemiologystudyfromAugust toOctober2015.Theywereadministeredanepidemiological questionnaireandserumsamplesweretestedforthe pres-enceofIgGtoZIKVusingtheEuroImmunanti-NS1IgGELISA detectionkitandaseroneutralizationassayforconfirmation ofpositives, as previouslydescribed.7 _{Theobserved global}

seroprevalencewas low(∼5%),peakingat10%and 7.7%in DoualaandBertoua,respectively,andaslowas2%inMaroua andNgaoundéré (Fig. 1).Inmultivariate analysis,the most significant risk factors associated with ZIKV seropositivity were“tobeasoldier”(p=0.021),a“highdistancetothe near-esthouse/shop”(p=0.042),and a“previousfamilialcaseof

YellowFever”(p=0.001).Togetherwiththelowvector capac-ityoftheAfricanperi-domesticmosquitoAedesaegypti,6_these

riskfactorspointtotheexistenceofa(peri-)sylvaticcycleof transmissionofZIKVinCameroon,similartothatofyellow fevervirus,ratherthantoanurban“dengue-like” transmis-sionofthevirus.

Altogether,ourfindingsindicatethattheimmunityofthe CameroonianpopulationagainstZIKVislowandthat circu-lationinurbanpopulationsisuncommon.Hence,theriskof epidemicspreadofZIKVdoesexist.Theepidemicemergence oftheAfricangenotypecannotbetotallyexcludedbutitwould imply afirst and uncertainstepofadaptation ofthe virus toperi-domesticAedesmosquitoes.Moreworrisomeonthe shorttermisthepotentialintroductioninAfricanurbanareas

brazj infect dis.2017;21(4):481–483

483

ofAsiangenotypeZIKVcurrentlycirculatingintheAmericas, aspreviouslysuggested bymodeling studies.8 _{The virus is}

likelytobeimportedbyinfectedtravelerscomingfrom epi-demicareasandhasthepotentialtobetransmittedbylocal peri-domestic mosquitoes. Our study provides biological evidence that such introduction would occur in popula-tions thatare globallyimmunologically naïveagainst ZIKV infectionandliveinareaswherepotentialepidemicvectors exist.

Thisobservationshouldleadtospecificsurveillanceefforts and to a broader and more systematicmapping ofat-risk populationsinAfrica.Italsoshouldigniteinterestin investi-gatingsimilarscientificandpublichealthissuesintheAsian population.

Conflicts

of

interest

Theauthorsdeclarenoconflictsofinterest.

Acknowledgements

Thiswork waspartiallysupportedbythe EuropeanUnion’s Horizon 2020 Research and Innovation Program under ZIKAllianceGrantAgreementno.734548.

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