MononucleosisSpotTestMedicallyreviewedbyArefaCassoobhoy,MD,MPH—WrittenbytheHealthlineEditorialTeam—UpdatedonDecember16,2020MonoHowthetestworksProcedureComplicationsUnderstandingtestresultsWhatisamononucleosisspottest?Amononucleosisspot(orMonospot)testisabloodtestusedtodeterminewhetheryouhavecontractedtheEpstein-Barrvirus,thevirusthatcausesinfectiousmononucleosis.Yourdoctormayorderthistestifyouhavesymptomsofmononucleosis.Mononucleosisisaviraldiseasethataffectscertainbloodcellsandcreatesflu-likesymptoms.Whatismononucleosis?MononucleosisisaviralinfectioncausedbytheEpstein-Barrvirus(EBV),whichisatypeofherpesvirusandoneofthemostcommonhumanviruses.Alsocalled“mono”and“thekissingdisease,”theillnessisn’tconsideredseriousorlifethreatening.Thisdiseasetypicallyaffectsteenagersandyoungadultsintheir20s.Thesymptomsofinfectiousmononucleosiscanmakeitdifficulttocontinuewithnormaldailyactivities.Symptomsmaylastfromseveralweekstoacoupleofmonths.Inrarecases,itcanlastseveralmonths.Symptomsofmononucleosisinclude:feversorethroatswollenglandsinneckandarmpitsseverefatiguebodyachesheadacheslossofappetiterashswollenspleen,liver,orboth(uncommon)Ifyouhavethesesymptomsforaweekorlonger,youmayhavemono.Yourdoctormayperformthemononucleosisspottesttoconfirm(orruleout)thediagnosis.Howdoesthetestdetectthevirus?Whenavirusinfectsthebody,theimmunesystemgoestoworktofightitoff.Thisisyourbody’sprotectivereaction.Itincludesthereleaseofcertainantibodies,or“fightercells,”chargedwithgoingaftertheviralcells.Themononucleosistestlooksforthepresenceoftwoantibodiesthattypicallyformwhencertaininfections—likethosecausedbytheEpstein-Barrvirus—arepresentinthebody.Onrareoccasions,thetestmayshowantibodieseventhoughyoudon’thavetheinfection.Thismayoccurespeciallyifyouhave:hepatitisleukemiarubellasystemiclupuserythematosusotherinfectiousdiseasesandsomecancersIfthetestcomesbacknegative,itmaymeanyoudon’thavetheinfectionorthatthetestwasperformedtooearlyortoolatetodetecttheantibodies.Yourdoctormightrecommendasecondtestinacouplewee