CXG_079e

GUIDELINESONTHEAPPLICATIONOFGENERALPRINCIPLESOFFOODHYGIENETOTHECONTROLOFVIRUSESINFOODCAC/GL79-2012INTRODUCTION1.Inrecentyears,viruseshavebeenincreasinglyrecognizedasimportantcausesoffoodbornediseases.Virusesaremicroorganismsthatdifferinsize,structureandbiologicalcharacteristicsfrombacteria.Virusesarestrictlyhost-dependentfortheirreplicationandhavetheirowntypicalhostrangeandcellpreference(tropism).Virusescanbetransmittedindifferentways,e.g.,viatherespiratoryorfaecal-oralroutes.Humanvirusescanbetransmitteddirectlyfromperson-toperson,butalsoindirectlyviavirus-contaminatedwater,air,soil,surfacesorfood.Someviruses(zoonoticviruses)aretransmittedfromanimalstohumans.Datafromrecentstudieshaveshownthatfoodborneviralinfectionsareverycommoninmanypartsoftheworld,despitethemeasuresalreadyinplacemainlytargetedatreducingbacterialcontamination.2.Thehumanentericvirusesmostfrequentlyreportedasinvolvedinfoodborneoutbreaksarenorovirus(NoV)andhepatitisAvirus(HAV).Othervirusessuchasrotavirus,hepatitisEvirus(HEV),astrovirus,Aichivirus,sapovirus,enterovirus,coronavirus,parvovirusandadenoviruscanalsobetransmittedbyfood,andanecdotalevidencesuggeststhelistoffoodbornevirusesmaybeevenlonger.Basedonthesymptomsofdisease,thesevirusescanbegroupedintothosethatcausegastroenteritis(e.g.,NoV),entericallytransmittedhepatitis(e.g.,HAV,thatreplicatesintheliver),andathirdgroupwhichreplicatesinthehumanintestine,butonlycausesillnessaftertheymigratetootherorganssuchasthecentralnervoussystem(e.g.,enterovirus).Themajorfoodbornevirusesarethosethatinfectviathegastrointestinaltractandareexcretedinfaecesand/orvomit,andareinfectiousforhumanswheningestedviatheoralroute.Asymptomaticinfectionsandsheddingarecommonandhavetobeconsideredinfoodproduction.3.Noteworthyaspectsoffoodbornevirusesandtheassociatedinfections/illnessesthatdeterminemanagementstrategiestobedifferentfrommanagementstrategiesforbacterialpathogens:•Virusesneedtoenterlivinghostcellsinordertobeabletomultiply(replicate).Unlikebacteria,theydonotreplicateinfood.Consequently,virusesdonotcausedeteriorationoftheproductandtheorganolepticpropertiesofthefoodarenotaffectedduetoviralcontamination.•Eventhoughhighnumbersofviralparticlesareshedinthestoolsofsymptomaticorasymptomaticinfectedpersons(e.g.,exceeding106particlespergramofstool)orinvomit,onlyafewviral/infectiousparticles(lessthan100)areneededtocauseinfectionthatmayleadtoillness.•Humanentericviruses,suchasNoVandHAV,areveryinfectiousandperson-to-personspreadisthemostcommontransmissionroute.Secondaryspreadofthesevirusesafterprimaryintroductionby,forexample,food-relatedcontamination,iscommonandoftenresultsinlarger,prolongedoutbreaks.•Non-envelopedviruses,suchasNoVandHAV,arecoveredinaprotein-basedstructurecalledacapsid.Envelopedviruses,suchasinfluenza,haveacapsidandarefurthercoatedinabiologicalmembranederivedfromthehostcell.Boththecapsidandenvelopestructuresinfluenceenvironmentalpersistenceandresistancetocleaninganddisinfectioninterventions.However,thenon-envelopedvirusestendtobemoreresistanttoinactivationfromsolvents(e.g.,chloroform)anddesiccation.•Virusestransmittedbythefaecal-oralroutecanpersistformonthsinfoodstuffsorintheenvironment(e.g.,insoil,water,sediments,bivalvemolluscsoronvariousinanimatesurfaces).Mostfoodbornevirusesaremoreresistantthanbacteriatocommonlyusedcontrolmeasures,(e.g.,refrigeration,freezing,pH,drying,UVradiation,heat,pressure,disinfection,etc.).•Freezingandrefrigerationtemperaturespreservevirusesandarebelievedtobeimportantfactorsthatincreasethepersistenceoffoodbornevirusesintheenvironment.Heatanddryingcanbeusedtoinactivateviruses,buttherearevirus-to-virusdifferencesinresistancetotheseprocesses.Thepresenceoforganicmatter,suchasfaecalmaterialandthefoodmatrixcaninfluencerelativeresistancetoheatanddrying.•Traditionalhandwashingpracticesmaybemoreeffectiveforinfectiousvirusreductionascomparedtotheuseofhandsanitizing-agents.Themajorityofchemicaldisinfectantsusedinfoodestablishmentsdonoteffectivelyinactivatenon-envelopedviruses,suchasNoVorHAV.•Zoonoticfoodbornetransmissionofvirusesisnotcommonlyreportedasisthecaseformanybacterialpathogens,suchasSalmonellaandCampylobacter,however,itdoesoccur,e.g.,forHEV.•Ingeneral,testingoffoodsforfoodbornevirusesischallengingandrequiresmatrix-dependentextractionandconcentrationtechniquesandisbasedondetectionofviralnucleicacids.•Thereisacurrentlackofmethodsforassessingthelevelofinactivationoffoodbornevirusesinfood.Thishasledtotheuseofsurrogateviruses,e.g.,theuseoffelinecalicivirusandmurinenorovirusinplaceofNoV.Whenevaluatingriskmanagementoptions,theuseofasurrogatewillnotalwaysmimictheresistanceoftheintendedfoodborneviruses.4.DuringtheFAO/WHOExpertmeetingon“VirusesinFood”1,NoVandHAVweredeterminedtobethevirusesofgreatestconcernfromafoodsafetyperspectivebasedontheincidenceofreportedfoodbornedisease,theseverityofdisease,including1FAO/WHO[FoodandAgricultureOrganizationoftheUnitedNations/WorldHealthOrganization].2008.VirusesinFood:Scientificadvicetosupportriskmanagementactivities:meetingreport.MicrobiologicalRiskAssess