SkipNavigationImportantUpdates:RecallonPhilipsRespironicsmedicaldevices|COVID-19vaccinationsPhilipsRespironicsissuedarecallforsomeCPAPandBiLevelPAPdevicesandmechanicalventilators.Learnmore. COVID-19:Wearevaccinatingpatientsages12+.Learnmore:Vaccines|Testing|PatientCare|VisitorGuidelines|Coronavirus|Self-Checker|EmailAlertsHealthHomeConditionsandDiseasesInfectiousMononucleosisFacebookTwitterLinkedinPinterestPrintWhatisinfectiousmononucleosis?Infectiousmononucleosisischaracterizedbyswollenlymphglands,fever,sorethroat,andextremefatigue.It’softenspreadthroughcontactwithinfectedsalivafromthemouth.Symptomscantakebetween4to6weekstoappearandusuallydonotlastbeyond4months.Transmissionisimpossibletopreventbecauseevensymptom-freepeoplecancarrythevirusintheirsaliva.Whatcausesinfectiousmononucleosis?InfectiousmononucleosisiscausedbytheEpstein-Barrvirus(EBV).AvariantofmononucleosisthatismilderthanEBVinfectiousmononucleosisiscausedbythecytomegalovirus(CMV).BothEBVandCMVaremembersoftheherpesvirusfamily:IntheU.S.,mostadultsbetween35and40yearsoldhavebeeninfectedwiththeEpstein-Barrvirus.Thisisaverycommonvirus.Whenchildrenareinfectedwiththevirus,theyusuallydonotexperienceanynoticeablesymptoms.However,uninfectedadolescentsandyoungadultswhocomeincontactwiththevirusmaydevelopanillnessverysimilartoinfectiousmononucleosis.TheEpstein-Barrvirus(EBV)maycauseinfectiousmononucleosisinadolescentsandyoungadults.However,evenafterthesymptomsofinfectiousmononucleosishavedisappeared,theEBVwillremaindormantinthethroatandbloodcellsduringthatperson'slifetime.Theviruscanreactivateperiodically,however,usuallywithoutsymptoms.Whatarethesymptomsofinfectiousmononucleosis?Mononucleosisusuallylastsfor1to2months.Thefollowingarethemostcommonsymptomsofmononucleosis.However,eachpersonmayexperiencesymptomsdifferently.Symptomsmayinclude:FeverSwollenlymphglandsintheneck,armpits,andgroinExtremefatigueSorethroatEnlargedspleenHeadandbodyachesLiverinvolvement,suchasmildliverdamagethatcancausetemporaryjaundice,ayellowdiscolo