【欧洲疾控中心】快速疫情评估-与食用发芽种子有关的跨境多血清型沙门氏菌爆发持续时间延长-2025

Suggestedcitation:EuropeanCentreforDiseasePreventionandControl,EuropeanFoodSafetyAuthority,2025.Prolongedcross-bordermulti-serovarSalmonellaoutbreaklinkedtoconsumptionofsproutedseeds–6March2025.ISBN978-92-9498-782-2;doi:10.2900/7051610;CataloguenumberTQ-01-25-013-EN-N

AlsopublishedinEFSASupportingPublications:TechnicalreportapprovedbyEFSAon6March2025;

doi:10.2903/sp.efsa.2025.EN-9315;Keywords:Salmonella,sprouts,multipleserovars;multi-countryoutbreak,WholeGenome

Sequencing(WGS).Requestor:EuropeanCommission;Questionnumber:EFSA-Q-2025-00109;correspondence:roa-efsa@efsa.europa.eu,ISSN:2397-8325.

©EuropeanCentreforDiseasePreventionandControl,EuropeanFoodSafetyAuthority,2025

JOINTECDC-EFSARAPIDOUTBREAKASSESSMENT

Prolongedcross-bordermulti-serovarSalmonellaoutbreaklinkedtoconsumptionofsprouted

seeds

6March2025

Abstract

Across-bordermulti-serovarSalmonellaentericaoutbreaklinkedtotheconsumptionofsproutedseedshas

beenongoinginEuropesince2023.BetweenJanuary2023andJanuary2025,509confirmedcasesof

salmonellosismeetingtheEuropeancasedefinitionwereidentifiedinnineEuropeanUnion/EuropeanEconomicArea(EU/EEA)countries:Belgium(1),Denmark(4),Estonia(1),Finland(94),France(3),Germany(30),theNetherlands(9),Norway(257)andSweden(110).OnecasewasalsoreportedbytheUnitedKingdom.The

outbreakencompasseseightSalmonellaserotypes,severalofwhicharerarelyreportedintheEU/EEA.Sproutswereidentifiedasthevehicleofinfectioninmultiplenationalinvestigations,whichwasconfirmedbyEU

centralisedwholegenomesequencing(WGS)analysis.

Sharingofepidemiological,traceability,andWGSdataacrosscountriesinbothpublichealthandfoodsafetysectors,wascrucialinlinkingsevennationaloutbreaksinFinland,Germany,NorwayandSwedentoacommonseedsupplierinItaly.FurtherfoodinvestigationslinkedthecommonsuppliertothreeseedgrowerslocatedinthesamegeographicalareaofItaly.Theroleoftheenvironmentintheseedcontaminationatgrowerlevel,

andofcross-contaminationsalongtheseedsupplychaincontributingtothemulti-strainoccurrence,shouldbefurtherinvestigated.

Foodsafetyauthoritiesinthecountriesconcernedimplementedcontrolmeasures,includingwithdrawaland

recallofinvestigatedbatches.Thissignificantlydecreasedcasenotifications.However,severalcountrieshavedetectednewcases,indicatingthatcontaminatedseedbatchesmaystillbeincirculationandfurther

interventionsneeded.Casesmaycontinuetooccuruntilthepoint(s)wheretheseedswerecontaminatedwithSalmonellacanbeidentifiedandproperlycontrolled.Seedproducersshouldapplyallproceduresnecessary

(e.g.GoodAgriculturalPractices(GAP))topreventmicrobialcontaminationofseedsintendedforsproutingandsproutproducersshouldimplementadequatefoodsafetymanagementsystemstoensureonlysafeproductsreachthemarket.

2

JOINTOUTBREAKASSESSMENTProlongedmulti-serovarSalmonellaoutbreaklinkedtoconsumptionofsproutedseeds–6March2025

Eventbackground

DuetoanongoingriskofinfectionswithmultipleSalmonellaserotypeslinkedtosproutedseedsinanumberofEU/EEAcountries,on16January2025theEuropeanCommissionaskedECDCandEFSAtoproduceajointrapidoutbreakassessment(ROA)totriggerfurtherpublichealthandfoodsafetyinvestigations.

BetweenJanuary2023andJanuary2025,multipleSalmonellaentericaoutbreaksweredetectedinseveralEuropean

countries,alllinkedtoexposuretoalfalfasproutsfromacommonseedsupplierinItaly(foodinvestigationsarereportedinthesectionMicrobiologicalandenvironmentalinvestigationsoffoodandcontrolmeasuresandinAnnex1).

ThefirstoutbreakoccurredinGermanyinJanuary2023(EpiPulseevent2023-FWD-00017)[1],causedby

S.Adelaide.Whileasourcewasnotidentifiedduringtheinitialinvestigation,theoutbreakstrainwaslaterdetectedinsproutedseeds.Inautumn2023,FinlandreportedanoutbreakofS.Enteritidis(2023-FWD-00069)linkedto

sproutedseeds,wheretheoutbreakstrainwasalsoisolatedfromproductsconsumedbythoseindividualsinvolved.CaseisolatesthatwerecloselygeneticallylinkedwerealsoidentifiedinGermany,althoughtheydiffered

demographicallyfromtheFinnishcasesandwereinvestigatedseparately(see2023-FWD-00071).ThesourceofinfectionfortheGermancaseswasnotidentified.

Norwaysubsequentlyreportedthreedistinctoutbreaks:S.TyphimuriumST36sub-strainA(May2024;2024-FWD-00049),S.Hvittingfoss(August2024;2024-FWD-00089),andS.NewportST31(October2024;2024-FWD-00116).Whilethoseinvolvedinallthreeoutbreaksreportedconsumingsproutedseeds,thestrongestevidencecamefromtheS.NewportST31outbreak,wherebothacase-controlstudyandlaboratorytestingofsproutsamplesconfirmedtheassociation.InAugust2024,SwedenreportedanoutbreakofmultiplecloselyrelatedstrainsofS.TyphimuriumST36(sub-strainB;2024-FWD-00108),whereconsumptionofsproutedseedswasfoundtobestronglyassociatedwithillnessinacase-controlstudy.AdditionalcaseswerealsoidentifiedinFinland,DenmarkandNorway.All

outbreaksandfoodinvestigationsweredocumentedontheEpiPulseandRASFFnotificationplatforms.

Outbreakstrains

FortheEuropeancasedefinitionusedinthisreport,anoutbreakstrainisdefinedasanystrainwhere:

•atleasttwocaseisolatesclusterbywholegenomesequencingAND

•atleasttwocaseswithintheclusterhavereportedexposuretoalfalfasproutsOR

•thegeneticclusterislinkedtoalfalfasproutsgrownfromseedssourcedfromtheimplicatedseedsupplieraccordingtooneofthefollowingcriteria:

-alfalfasproutproductsconsumedbythoseinvolvedweretracedbacktotheimplicatedseedsupplierOR

-thesamestrain(clusteringwithcaseisolatesbywholegenomesequencing)wasindependentlyisolatedfromalfalfasproutsgrownfromseedssourcedfromtheimplicatedseedsupplier.

Thestrainsmeetingthesecriteriaandstrain-specificcoregenomeMLSTallelicdifference(AD)thresholdsarepresentedinTable1.

Table1.OutbreakreferencestrainssharedinEpiPulseperserotypeandevent

#

Serotype

Sequencetype

Threshold1

Noof

reference

strains

AssociatedEpiPulseevent(s)2

01.

S.Adelaide

10506

10AD

1

•2023-FWD-00017(Germany)

02.

S.Enteritidis

11

5AD

2

•2023-FWD-00069(Finland)

•2023-FWD-00071(Germany)

03.

S.Hvittingfoss

446

10AD

1

•2024-FWD-00089(Norway)

04.

S.Kinondoni

5447

20AD

2

•2024-FWD-00116(Norway)

05.

S.Kisarawe

5805

20AD

3

•2024-FWD-00116(Norway)

06.

S.Newport

31

5AD

2

•2024-FWD-00116(Norway)

07.

S.Richmond

909

20AD

1

•2024-FWD-00108(Sweden)

08.

S.Typhimurium

36(sub-strainA)

5AD

1

•2024-FWD-00049(Norway)

09.

S.Typhimurium

36(sub-strainB)

5AD

14

•2024-FWD-00108(Sweden)

1ThresholdsforinclusionintheEuropeancasedefinitionarepresentedasnumberofallelicdifferences(AD)fromthereferencestrainsisolatedfromhumancasesprovidedbythecountriesthatlaunchedeachinvestigation.

2TheEpiPulseeventIDsrepresenttheoriginaloutbreakinvestigationduringwhichthestrainswereisolated

JOINTOUTBREAKASSESSMENTProlongedmulti-serovarSalmonellaoutbreaklinkedtoconsumptionofsproutedseeds–6March2025

3

Accordingtothesecriteria,nineoutbreakstrainswereidentifiedthroughsevenindependentoutbreakinvestigationsundertakenacrossfourEuropeancountries(Finland:1,Germany:2,Norway:3,Sweden:1).Eightdistinctserotypesandsequencetypes(ST),wereidentifiedinhumancases,includingtwosub-strainsofS.TyphimuriumST36(AandB),whicharedescribedseparatelyduetosignificantgeneticdifferencesbetweenthem(>300allelicvariations).

AdatacalltosupportthisrapidoutbreakassessmentwasissuedbyECDCtoEU/EEAcountriestoperformadditionalretrospectivecasefindingforeachofthelistedoutbreakstrains.Thedatacallalsoincludedtworaresequencetypes(S.KotteST11989andS.NewportST166)thathadalsobeenisolatedfromsproutedseeds;however,nohumancaseswereidentified.

Europeanoutbreakcasedefinitions

TheEuropeanoutbreakcasedefinitionsareprovidedbelow:

Aconfirmedoutbreakcaseisdefinedas:

Alaboratory-confirmedcaseofanySalmonellaentericaoutbreakstraindefinedinTable1,withsymptomonsetonorafter1January2023(dateofsamplingordateofreceiptbythereferencelaboratoryifdateofonsetisnot

available);

AND

fulfillingatleastoneofthefollowinglaboratorycriteria:

•fallswithinserotype-specificcoregenomeallelicdifferencethresholds(orSNPdifferences,respectively)definedinTable1withrespecttotherepresentativeoutbreakreferencestrainswhenanalysedinnationalbioinformaticspipelinesOR

•clusteringwithintheserotype-specificcoregenomeallelicdifferencethresholdsdefinedinTable1inacentralisedsingle-linkageanalysis;

OR

fulfillingtheepidemiologicalcriterion:

•epidemiologicallylinkedtoalaboratory-confirmedcasebasedonanationaloutbreakcasedefinition.

4

JOINTOUTBREAKASSESSMENTProlongedmulti-serovarSalmonellaoutbreaklinkedtoconsumptionofsproutedseeds–6March2025

Epidemiologicalandmicrobiologicalinvestigationsofhumancases

BetweenJanuary2023andJanuary2025,509laboratoryconfirmedcasesofsalmonellosislinkedtothisoutbreakwerereportedbynineEU/EEAcountries;Belgium(1),Denmark(4),Estonia(1),Finland(94),France(3),Germany(30),theNetherlands(9),Norway(257)andSweden(110).Inaddition,onecasewasreportedbytheUnited

Kingdom(Table2.).Nordiccountries(particularlyNorway,SwedenandFinland)werethemostaffected.The

majorityofcaseswerefemale(66%,n=336)andadult(median

1

:44years,range:1–90years).Informationonhospitalisationwasavailableandconfirmedfor100cases(20%),themajorityofwhichwereinfectedwith

SalmonellaTyphimuriumST36(n=44)andS.NewportST31(n=39).Nodeathswerereported.Table2

summarisesadescriptionofcasedemographics,microbiologicalandepidemiologicalevidence.AllcaseisolateswerelinkedbyWGStogeneticclusterswithconfirmedlinkstoalfalfasproutsandmeettheEuropeancasedefinitionforthisoutbreak,asdescribedintheprevioussection.

Table2.DemographicsummaryoflaboratoryconfirmedSalmonellaoutbreakcases,stratifiedby

countryandserotypeinnineEU/EEAcountries(n=509cases),January2023-January2025

Country

Outbreakstrain

Nconfirmedcases

Age(years)

Median

(range)

Epidemiologicalandmicrobiologicalevidence

Total

Female

Male

Interviews1

Receipts2

Study3

Sproutisolates4

Belgium

S.Enteritidis11

1

0

1

*(30-40)

-

-

-

-

Denmark

S.Typhimurium36a

2

1

1

42(20-65)

-

-

-

-

S.Typhimurium36b

2

0

2

65(50-80)

-

-

-

-

Estonia

S.Typhimurium36b

1

1

0

*(40-50)

-

-

-

-

Finland

S.Enteritidis11

75

49

26

40(2-90)

Trawling

-

Case-case

S.Enteritidis11

S.Kinondoni5447

1

1

0

*(30-40)

-

-

-

-

S.Typhimurium36b

18

8

10

36(14-66)

Trawling

-

-

S.Kisarawe5805

France

S.Enteritidis11

3

1

2

17(5-28)

-

-

-

-

Germany

S.Adelaide10506

14

9

5

41(11-76)

Trawling

-

-

S.Adelaide10506

S.Enteritidis11

13

9

4

11(1-81)

-

-

-

-

S.Kinondoni5447

1

0

1

*(80-90)

-

-

-

-

S.Newport31

1

1

0

*(70-80)

-

-

-

-

S.Typhimurium36b

1

1

0

*(20-30)

-

-

-

-

The

Netherlands

S.Adelaide10506

1

0

1

*(65-75)

-

-

-

-

S.Kinondoni5447

2

2

0

38(20-55)

-

-

-

-

S.Kisarawe5805

3

2

1

25(20-85)

-

-

-

-

S.Typhimurium36b

3

1

2

75(20-85)

-

-

-

-

Norway

S.Hvittingfoss446

12

8

4

52(20-71)

Trawling

Yes

-

-

S.Kinondoni5447

2

2

0

29(1-58)

Targeted

-

-

S.Kinondoni5447

S.Kisarawe5805

3

2

1

45(45-56)

Targeted

-

-

S.Kisarawe5805

S.Newport31

105

74

31

49(1-90)

Trawling/

.targeted

Yes

Case-

control

S.Newport31

S.Richmond909

1

1

0

*(80-90)

-

-

-

-

S.Typhimurium36a

14

10

4

44(6-78)

Trawling

Yes

-

-

S.Typhimurium36b

120

81

39

54(2-87)

Targeted

Yes

-

-

Sweden

S.Kinondoni5447

4

1

3

28(8-59)

-

-

-

-

S.Newport31

1

1

0

*(80-90)

-

-

-

-

S.Richmond909

5

5

0

63(38-76)

Trawling

-

-

-

S.Typhimurium36b

100

65

35

43(1-89)

Trawling

Yes

Case-

control

-

TotalforEU/EEAcountries

509

336

173

44(1-90)

United

Kingdom

S.Typhimurium36b

1

0

1

*(50-60)

-

-

-

-

*Forcountry/serovarcombinationswithasinglecase,agerangehasbeenreplacedwiththe10-yearagegroupforthecase.

1Exposuredatasourcedfromroutinesurveillancequestionnaires,trawlingquestionnaires,ortargetedcaseinterviews

2Groceryreceiptsorpurchaseorderswithevidenceofsproutedseedsbeingpurchased.

3Analyticalstudieswithstatisticallysignificantassociationbetweenillnessandsproutconsumption.

4Strains(serotypeandsequencetype)isolatedfromsproutedseeds

+Highlightedrowsindicatecountrieswithprimaryoutbreakinvestigations;otherstrainsweredetectedaspartoftheseinvestigations.

Epidemiologicalevidenceofexposuretosproutedseedswasgatheredviacaseinterviews,trawling,targeted,orroutinesurveillancequestionnaires(Table2).ForthethreelargestoutbreaksinFinland,NorwayandSweden,case-caseand

1Crudemediancalculatedfromcountry-specificmedianage

JOINTOUTBREAKASSESSMENTProlongedmulti-serovarSalmonellaoutbreaklinkedtoconsumptionofsproutedseeds–6March2025

5

case-controlstudieswerealsoundertaken.InFinland,acase-casestudyconductedduringthe2023S.EnteritidisST11outbreak,involving75casesfromdifferentpartsofthecountry,wasfoundtosupportthesproutshypothesis.In

Norway,acasecontrolstudyundertakenduringtheS.NewportST31outbreakinOctoberandDecember2024,foundthatcases(n=12)werethreetimesmorelikelytohaveeatensproutedseedspriortoonsetthancontrols(n=35)(LASSOregressionpenalisedadjustedoddsratioof3.13).Moreover,purchaseoftheimplicatedproductswas

confirmedviagrocerystorereceiptsforeightcases.InSweden,acasecontrolstudy,undertakenduringthe

S.TyphimuriumST36outbreakfromAugusttoNovember2024,foundthatconsumptionofalfalfasproutswasfourtimesmorelikelyamongcasesthancontrols(adjustedoddsratio:4.15,95%confidenceinterval:1.15-15.1).Inallthreestudies,forsomecasesmultiplestrandsofevidencewereavailable(self-reportedconsumptionofalfalfasprouts,groceryreceipts,andmicrobiologicalfindingsinpackagesofsproutedseedspurchasedbytheindividualinvolved).

Furtherdetailsoncountry-specificinvestigationsareprovidedinthefollowingsection.

Finland(oneoutbreak)

S.EnteritidisST11(2023-FWD-00069)

FinlandwastheepicenterofanS.EnteritidisST11outbreakfromAugusttoOctober2023,involvingatotalof75cases(EpiPulseevent2023-FWD-00069).GeneticallylinkedcaseisolateswerealsoreportedbyBelgium(1),France(3)andGermany(13)whichmettheEuropeancasedefinition.TheclusterofGermancasesandthegenetically

linkedBelgiancasewerereportedandinvestigatedasaseparateevent(seebelow).Acase-casestudyidentifiedalfalfasproutsastheprobablevehicleofinfection.Theoutbreakstrainwasalsoisolatedfromsproutedseeds

sampledfromapackagebelongingtooneofthecases.

Otherlinkedoutbreakstrains

BetweenAugustandDecember2024,Finlandidentified18S.TyphimuriumST36sub-strainBcasesandone

S.KinondoniST5447casethatwerecloselygeneticallylinkedtootheroutbreakstrainsoriginallyreportedbySwedenandNorway,respectively.S.Kisarawewasisolatedfromanopenedalfalfaandredcloversproutmixpackage,sampledfromthehomeofoneofthecaseswithS.TyphimuriumST36sub-strainB.

Germany(twooutbreaks)

S.AdelaideST10506(2023-FWD-00017)

Germanyreported14caseslinkedtoamulti-regionS.AdelaideST10506outbreakthatoccurredoverasix-monthperiodfromJanuarytoJune2023(EpiPulseevent2023-FWD-00017).Fourofninecasesinterviewedreported

consumingsproutproducts.TheNetherlandsreportedonegeneticallylinkedcase(within5ADoftheGermanreferencestrain)fromJuly2023.TheoutbreakstrainwasalsoindependentlyisolatedfromasampleoforganicsproutssoldinGermany.

S.EnteritidisST11(2023-FWD-00071)

BetweenJulyandSeptember2023,Germanyreported12casesthatweregeneticallylinkedtotheFinnish

S.EnteritidisST11outbreak(confirmedwithECDC-EFSAcentralisedWGSanalysisasbeing3ADfromtheFinnishisolate,sampledfromasproutpackagebelongingtooneofthecases).ThecaseswerereportedasaseparateeventinEpiPulse(2023-FWD-00071)duetothedifferenceindemographicsandstrongerclonalityofcaseisolates.The

casesaffectedwerepredominantlyfemalechildrenfrommultipleregionsacrossGermanyandmostcaseisolates

clusteredverycloselytogether(within1AD).Ayearlater,inSeptember2024,athirteenthcasewasidentified

(isolatewith1ADcomparedtotheGermanreferencestrain)inafemalechild.Belgiumalsoreportedacloselylinkedcaseisolate(with1ADcomparedtotheGermanreferencestrain)fromanadultmale,isolatedinSeptember2023.Thevehicleofinfectionforthissub-clusterwasnotidentified.

Otherlinkedoutbreakstrains

GermanyalsoreportedoneeachofS.TyphimuriumST36sub-strainBandS.KinondoniST5447caseswithisolatescloselylinkedtotheSwedishandNorwegianoutbreakstrains,respectively,fromSeptember2024.

Norway(threeoutbreaks)

S.TyphimuriumST36sub-strainA(2024-FWD-00049)

Norwayreported14caseslinkedtoamulti-regionS.TyphimuriumST36sub-strainAoutbreakthatoccurred

betweenMayandAugust2024(EpiPulseevent2024-FWD-00049).Oninvestigation,themajority(ninecases)

reportedconsumptionofsproutedseedsintrawlingquestionnairesandtherewasnoindicationofanyassociationwithtravel.Theoutbreakwascharacterisedbyrelativelyhighhospitalisationrates(57%)andincludedtwocases

withbacteremia.Denmarkalsoidentifiedtwogeneticallylinkedcases(1-2ADcomparedtotheNorwegianreferencestrain)thathadnottravelledoutsideofDenmarkpriortoonset,fromJuly2024andJanuary2025,respectively.

6

S.HvittingfossST446(2024-FWD-00089)

BetweenAugustandOctober2024,Norwayexperiencedasecondoutbreaklinkedtoconsumptionofsproutedseeds(EpiPulseevent2024-FWD-00089).TheoutbreakstrainwasS.HvittingfossST446andinvolved12casesfrom

differentregionsacrossNorway.Aswiththefirstoutbreak,therewasnoindicationofforeigntravel,andforfiveofthecasesthetrawlingquestionnairesreportedconsumptionofsproutedseedspriortoonset.

S.NewportST31(2024-FWD-00116)

BetweenOctoberandDecember2024,Norwayidentified105geographicallydispersedcaseslinkedtoathird

outbreak;thecausativeagentsweretwodistinctclustersofS.NewportST31(2024-FWD-00116).Themajorityofcasesreportedconsumptionofalfalfasproutspriortoonset,andthisassociationwasalsocorroboratedwithacasecontrolstudyandevaluationofgroceryreceipts.Twoadditionalgeneticallylinkedcasesinadultfemalesaged70–90yearsfromNovemberandDecember2024werereportedbySweden(4SNPscomparedtotheNorwegianreferencestrain)andGermany(3ADfromtheNorwegianreferencestrain),respectively.Theoutbreakstrain(S.NewportST31)wasisolatedfromanopenpackageofsproutedseeds,sampledfromthehomeofanindividualinvolvedinoneofthecases(0ADbetweencaseandsproutisolate).S.NewportST31,S.NewportST166,S.KisaraweST5805,S.KinondoniST5447andS.KotteST11989werealsoisolatedfromsproutedseedssampledatarestaurantlinkedtotheS.Newportoutbreakinvestigation.

Otherlinkedoutbreakstrains

BetweenNovemberandDecember2024,Norwayalsoreported120casesofS.TyphimuriumST36sub-strainB(outbreakstrainscirculatinginSwedenandreportedinEpiPulseevent2024-FWD-00108).TwoS.KinondoniandthreeS.Kisarawecasesinindividualswhoreportedconsumingsproutedseedspriortoonsetweresubsequentlyidentifiedviaisolatesthatweregeneticallysimilar(within20AD)tothoseisolatedfromsproutedseeds.One

S.RichmondST909casewasidentifiedviageneticlinkagetoastrainthathadbeenidentifiedbySwedenasalsolinkedtoconsumptionofsproutedseeds.

Sweden(oneoutbreak)

S.TyphimuriumST36sub-strainB(2024-FWD-00108)

BetweenAugustandNovember2024,Swedenreportedanoutbreakof100casesofS.TyphimuriumST36sub-

strainB.Caseswereinfectedwith14distinctbutgeneticallyrelatedstrains(allwithinthesame53SNPcluster)thatwereeachdominantforashorttimespan(mainlythreetosixweeks)beforebeingreplacedbyanotherstrain.The14clusteredstrainsweregeneticallydistinctfromanyothersthathadbeenidentifiedintheSwedishsequencing

databasesince2019.Somestrainswereinitiallyinvestigatedandreportedasseparateoutbreaks(seeEpiPulse

events2024-FWD-00079,2024-FWD-00088and2024-FWD-00104)beforebeingconsolidatedintoasingleoutbreakinvestigation(EpiPulseevent2024-FWD-00108).CasesweregeographicallydispersedacrossSweden(18of21

regions),andhadnottravelledpriortoonset.Themajoritywerefemale(n=65).Theresultsofacasecontrol

studygavestrongindicationsthatnationallyproducedalfalfasproutswerethevehicleofinfection.Sevenadditionalcountrieshavesinceidentifiedcaseisolatesthataregeneticallylinkedtooneormoreofthe14Swedish

S.TyphimuriumST36referencestrains:Estonia(oneinQ42023),theUnitedKingdom(oneinQ22024),theNetherlands(3),Finland(7),Germany(1),Denmark(2)andNorway(120).

Otherlinkedoutbreakstrains

InadditiontotheS.NewportcaselinkedtotheNorwegianoutbreakmentionedabove,Swedenidentifiedafurtherninecaseswithisolatesgeneticallylinkedtootheroutbreakstrains;fourS.KinondoniST5447(11–20SNPsfromNorwegiancaseisolatesand15–23SNPsfromanItaliansproutisolate),andfiveS.RichmondST909(onecase

reportedconsumptionofsproutedseedsinatrawlingquestionnaireandallfivecaseisolatesweregeneticallylinkedtoastrainsampledfromsproutedseedsinItaly).

Outbreaktimelines

Thetimelineofeachlinkedoutbreak,stratifiedbySalmonellaserotypeandcountry,ispresentedinFigure1.

S.AdelaideandS.Enteritidisoutbreaksoccurredprimarilyinquarters1–2and3of2023,respectively,while

S.Typhimurium,S.Newportandtheremainingstrainsweredominantinquarters2–4of2024.TwogeneticallyandtemporallydistinctS.Typhimuriumsequencetype36strains(sub-strainsAandB)causedoutbreaksduringdifferenttimeperiods.Sub-strainAwasprevalentinNorwayinquarters2–3,whilesub-strainBwasprevalentinFinlandinquarter2,Swedeninquarters3–4andinNorwayinquarter4,2024.

7

Figure1.Timelineofassociatedeventsbyserovarandcountryofoccurrence

Thenumberofcaseswithineachlinkedoutbreak,stratifiedbystrainandcountry,arepresentedinFigure2.TheserotypeswiththehighestnumberofcaseswereS.TyphimuriumST36sub-strainB(n=246),followedby

S.NewportST31(n=107)andS.EnteritidisST11(n=92).Fewerthan100caseshavebeenreportedforall

otherserotypestodate.Geneticallylinkedcaseisolatesfromatleasttwocountrieshavebeenreportedforalleightoutbreakstrains,withtheexceptionofS.HvittingfosswhichwasonlydetectedinNorway.S.TyphimuriumST36sub-strainBhasthewidestgeographicaldistribution,withcasesreportedfromeightcountriestodate.

8

Figure2.Casedistributionbyserotypeandcountry

9

Microbiologicalandenvironmental

investigationsoffoodandcontrolmeasures

Thissectionsummarisestheresultsofthefoodinvestigationsperformedbythefoodsafetyauthoritiesinall

countriesconcernedbythismulti-countryoutbreak(Finland,Germany,Italy,theNetherlands,Norway,Spain,andSweden).Thetraceabilityandanalyticalresultsweresharedasof21February2025bytheMemberStatesinvolvedundertheRASFFnotifications2024.8840(12EuropeanCommission(EC)validatedfollow-ups,fups),2024.9155

(eightfups),2023.6714(fivefups),2025.0200(eightfups),2025.0402(sixfups),2023.4749(sevenfups),2024.7982(sevenfups),and2024.8206(fourfups).AdetaileddescriptionisavailableinAnnex1.AvisualrepresentationofthesefoodinvestigationsisdisplayedinFigures3aand3b.

Briefly,traceabilityinvestigationspointedtowards10sproutproducts,includingtwowithnolabellinginformation.Intotal,13sproutbatcheswereidentified.Moreover,theinvestigationsidentified23seedbatches,includingfivewithnolabellinginformation.The23seedbatchesincludedfiveseedconsignmentsfromprimaryproductionand18seedbatchesfromsuppliers.Atotalofninesproutproducers(insixcountries),twoseedsuppliers,andthreeseed

growers(allinItaly)wereidentified.

Sevensproutproductsoutof10(includingthreewithnolabellinginformation),correspondingtoeightbatches,werereportedtobepositiveforSalmonella(serovars:NewportST166andST31,EnteritidisST11,Adelaide,

KisaraweST5805,RichmondST909,Kotte,andKinondoniST5447)(Table3).

TheseSalmonellapositivesproutproductswereproducedbysixsproutproducersinfivecountries,withseedstracedbacktothesameseedsupplier(ItalianSeedSupplierA)andmainlytoasecondseedsupplier(theItalianSeedSupplierB)locatedinItaly(Figures3aand3b).

Sixofthesevenpositivesproutproductsweretracedbacktothethreegrowers(ItalianGrowerA,ItalianGrowerBItalianGrowerC)locatedinthesamegeographicalareaofItaly(Figures3aand3b).

Inaddition,oneenvironmentalsamplepositiveforSalmonella(serovar:KisaraweST5805),collectedon28November2024attheNorwegianSproutsProducerCwasreported(RASFF2024.9155)(Figures3a).

On21January2025,thefoodsafetyauthorityinItalyannouncedinRASFF2025.0402thatastrategicsamplingofseedswouldbecarriedoutbythelocalcompetentauthoritiesandanauditwouldbecarriedoutbythenationalfoodauthority(mid-February2025)attheItalianSeedSupplierA.

On5February2025,thelocalcompetentauthoritycarriedoutanofficialsamplingattheItalianSeedSupplierB.Salmonellawasnotdetectedintwoseedconsignmentssampled