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Outbreak of Histoplasmosis Among Cavers Attending the National Speleological Society Annual Convention, Texas, 1994

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Outbreak of Histoplasmosis Among Cavers Attending the National Speleological Society Annual Convention, Texas, 1994
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DAVID A. ASHFORD, RANA A. HAJJEH, MICHAEL F. KELLEY, LEO KAUFMAN, LORI HUTWAGNER, AND MICHAEL M. McNEIL Meningitis and Special Pathogens Branch, Division of Bacterial and Mycotic Diseases, National Center for Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia; Communicable Disease Control, Texas Department of Health, Austin, Texas Abstract. In June 1994, 18 people developed serologically confirmed histoplasmosis following cave exploration associated with the annual National Speleological Society Convention in Bracketville, Texas. Six others had an undiagnosed illness suspected to be histoplasmosis. Two persons were hospitalized. We conducted a survey of con- vention attendees and a nested case-control study of those entering caves. We also conducted a histoplasmin skin test survey of a subgroup of the society, the Texas Cavers Association, who were attending a reunion in October 1994. Among the national convention attendees, exposure to two caves was identified as responsible for 22 (92%) of the 24 cases; 12 (75%) of 16 people exploring one cave (Cave A) and 10 (77%) of 13 exploring a separate cave (Cave B) developed acute histoplasmosis. Additional risk-factors included fewer years of caving experience, longer time spent in the caves, and entering a confined crawl space in Cave A. Of 113 participants in the separate skin test survey, 68 (60%) were found to be skin test positive, indicating previous exposure to Histoplasma capsulatum. A positive skin test was significantly associated with male sex and more years of caving experience. Those less experienced in caving associations should be taught about histoplasmosis, and health care providers should pursue histories of cave exposure for patients with bronchitis or pneumonia that does not respond to initial antibiotic therapy.
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899Am.J.Trop.Med.Hyg., 60(6),1999,pp.899 Copyrightq1999byTheAmericanSocietyofTropicalMedicineandHygieneOUTBREAKOFHISTOPLASMOSISAMONGCAVERSATTENDINGTHENATIONAL SPELEOLOGICALSOCIETYANNUALCONVENTION,TEXAS,1994DAVIDA.ASHFORD,RANAA.HAJJEH,MICHAELF.KELLEY,LEOKAUFMAN,LORIHUTWAGNER,ANDMICHAELM.McNEIL MeningitisandSpecialPathogensBranch,DivisionofBacterialandMycoticDiseases,NationalCenterforInfectiousDiseases, CentersforDiseaseControlandPrevention,Atlanta,Georgia;CommunicableDiseaseControl,TexasDepartmentofHealth, Austin,TexasAbstract. InJune1994,18peopledevelopedserologicallyconrmedhistoplasmosisfollowingcaveexploration associatedwiththeannualNationalSpeleologicalSocietyConventioninBracketville,Texas.Sixothershadan undiagnosedillnesssuspectedtobehistoplasmosis.Twopersonswerehospitalized.Weconductedasurveyofconventionattendeesandanestedcase-controlstudyofthoseenteringcaves.Wealsoconductedahistoplasminskintest surveyofasubgroupofthesociety,theTexasCaversAssociation,whowereattendingareunioninOctober1994. Amongthenationalconventionattendees,exposuretotwocaveswasidentiedasresponsiblefor22(92%)ofthe 24cases;12(75%)of16peopleexploringonecave(CaveA)and10(77%)of13exploringaseparatecave(Cave B)developedacutehistoplasmosis.Additionalrisk-factorsincludedfeweryearsofcavingexperience,longertime spentinthecaves,andenteringaconnedcrawlspaceinCaveA.Of113participantsintheseparateskintest survey,68(60%)werefoundtobeskintestpositive,indicatingpreviousexposureto Histoplasmacapsulatum. A positiveskintestwassignicantlyassociatedwithmalesexandmoreyearsofcavingexperience.Thoselessexperiencedincavingassociationsshouldbetaughtabouthistoplasmosis,andhealthcareprovidersshouldpursuehistories ofcaveexposureforpatientswithbronchitisorpneumoniathatdoesnotrespondtoinitialantibiotictherapy. Histoplasmosisiscausedby Histoplasmacapsulatum, a dimorphicfungusthatgrowsinsoil.IntheUnitedStates, theMississippiandOhioRiverValleysareconsideredareas where H.capsulatum isendemic.In1981,beforetheepidemicofacquiredimmunodeciencysyndrome(AIDS),it wasestimatedthat50,000,000casesoccurannuallyin theUnitedStatesandofthose,500wereseveredisseminated infections.1However,mostinfectionsgoundiagnosed,since patientsusuallyrecoverwithoutmedicalattention.1Theinfectionresultsprimarilyfrominhalationofaerosolizedsporesfromsoil.Histoplasmosis(oncereferredtoas cavedisease)canbeacquiredbyoccupationalorrecreational exposuretoenvironmentalsources,usuallyinareaswithendemichistoplasmosis.Cavesrepresentoneofthefocithat favorthepropagationofthefungus,2,3andbat-inhabited cavesmayharbor H.capsulatum eveninareaswherehistoplasmosisisoflowendemicity.4Thesignicanceofbirdandbatdroppingsintheecology ofhistoplasmosis,throughenhancingconditionsfor H.capsulatum growth,hasbeendescribed.5Inadditiontoimprovingsoilconditionswithguano,batscontributetopropagationof H.capsulatum bytransmittingtheorganismto newsites.10,11,13Thisisbecausethegastrointestinaltractsof batscanbecolonizedwith H.capsulatum.13Unlikebatsand othermammals,avianspeciesdonotharborthefungus,possiblybecausetheircoretemperaturesaretoohigh. Althoughcavinghasbeenshowntobeassociatedwith exposureto H.capsulatum, reviewoftheliteraturesuggests thatcave-associatedepidemicsareuncommonornotrecognized,4andlittleisknownaboutinfectionratesassociated withthisactivity.Thereareanestimated50,000caversin theUnitedStates(LuckinsR,President,NationalSpeleologicalSociety,unpublisheddata). FromJune19to26,1994approximately620membersof theNationalSpeleologicalSocietyattendedtheirannualconventioninBrackettville,Texas.Conventionparticipants campedout-of-doorsandwereinvolvedinworkshopsand dailyexcursionsforcaveexploration.Duringtheconvention,excursionswereorganizedfor19differentcaves.DuringthelasttwoweeksofJuly,fourconventionattendees developedheadache,fever,cough,myalgia,severefatigue, andchestpain.Twopersonswerehospitalizedformorethan oneweek;theyweresuspectedtohaveacutepulmonary histoplasmosisandtheyrespondedtoantifungaltherapy.Serumspecimensfromthefourpatientsweretestedbythe complementxation(CF)andimmunodiffusion(ID)assays atCDCandfoundpositiveforantibodiesto H.capsulatum.14Biopsyspecimenswerenotavailableforanalysis. Theobjectivesofourinvestigationweretodeterminethe ratesofclinicallyapparentinfectionamongconventionattendees,assesstheextentofassociatedmorbidity,determine whichcaveswereassociatedwithinfection,deneriskfactorsassociatedwithinfection(includingcavesvisited,activitiesincaves,environmentalexposure,age,sex,race,occupation,andpredisposingmedicalconditions)amongthose enteringsuspectcaves,andestimatetheprevalenceof H. capsulatum infectioninasubgroupofcavers. Todeterminethesizeoftheoutbreakandtoidentifyrisk factorsforinfection,weconductedacase-ndingsurveyof NationalSpeleologicalSocietymembers,acase-control studyofconventionparticipants,andacohortstudyofcaversenteringhigh-riskcaves.Inaddition,becauselittleis knownabouttheprevalenceofinfectionamongwhatisconsideredtobeahigh-riskgroup,weconductedaseparate studytoestimatetheprevalenceofhistoplasmosisamong caversattendingareunionoftheTexasCavers'Association, asubpopulationofthesociety.METHODSCasedenition. Forthepurposesofthisinvestigation,a conrmedcaseofacutehistoplasmosiswasdenedasonset ofillnessbetweenJune28andJuly30,1994andapositive serologyfor H.capsulatum infection(CFtitergreaterthan

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900ASHFORDANDOTHERS FIGURE1.EpidemiccurveofacutehistoplasmosiscasesfollowingtheNationalSpeleologicalSocietyConventioninBracketville, Texas,June18,1994.1:32orthepresenceofMbandsinIDtest)inacaverwho attendedtheconvention.Whenserawerenotavailable,a suspectedcasewasdenedasacaverwhoattendedtheconventionandhadonsetofillnessbetweenJune28andJuly 30,1994,andfever,chills,headache,cough,andtwoofthe followingsymptoms:fatigue,sweats,myalgias,orchest pain. Casending. Bydistributingthequestionnaireinthesociety'smonthlynewspublication,weconductedasurveyof conventionattendeestoidentifyadditionalcasesofhistoplasmosis.Thequestionnaireincludedquestionsregarding attendanceoftheconventioninBrackettville,demographic variables,cavesenteredduringtheconvention,timespent caving,symptoms,treatment,underlyingillness,current therapies,andoutcome.Serumwasobtainedfrompersons whoweresuspectedcases.Eachparticipant,oraphysician he/shedesignated,wasnotiedofserologicresultsandwas providedinformationaboutsymptomsandmanagementof histoplasmosis.Informedconsentwasobtainedfromparticipantsinthisstudy,andtheguidelinesforhumanexperimentationoftheU.S.DepartmentofHealthandHumanServiceswerefollowed. Case-controlstudy. Todeterminewhichof19cavesvisitedduringtheconventionwereassociatedwithinfection, weconductedanestedcase-controlstudyusingresponsesto thesurveyofconventionparticipants.Twocontrolspercasepatientwerechosenrandomlyfrom221respondentswho attendedtheconvention,enteredcaves,butdidnotdevelop illness.Patientsandcontrolswerecomparedregarding whichcaveswerevisitedduringtheconvention. Cohortstudy. Twenty-nineconventionparticipantswho enteredthetwocaves(CaveAorCaveB)associatedwith infectionwereevaluatedforriskfactorsforhistoplasmosis, includingage,yearsofcavingexperience,pre-existingillness,andspecicactivitiesinthecaves(e.g.,rappeling[slidingdownarope]). Histoplasminskintestsurvey. Inaseparatestudy,we conductedasurveyattheannualreunionoftheTexas Caver'sAssociationthatwasheldOctober21,1994.Afterobtaininginformedconsent,weadministeredaquestionnaireto113participantsandappliedahistoplasminskintest. Histoplasmin(Parke-DavisLaboratories,Detroit,MI)and spherulin(ALKLaboratories,Berkeley,CA)asacontrol, wereappliedintradermallytoallmeetingattendeeswho agreedtobetestedandwereread3048hrlaterbythesame observer.Abloodspecimenwasalsoobtainedfromallconsentingparticipants.Askintestwasconsideredpositiveif induration$5mmwaspresent. Laboratoryassays. Bloodsampleswereallowedtoclot for26hr,andserumwasseparated,frozen,andshippedto CDCfortesting.Serumspecimensweretestedforantibodies to H.capsulatum bybothCFtestswithhistoplasminand yeast-formantigensandbyIDwithhistoplasmin.Complementxationtiters$1:32andthedetectionofMorboth MandHbandswiththeIDassaywereconsideredpresumptiveevidenceofacuteinfectionwith H.capsulatum.14IntheIDassay,thepresenceofMorHprecipitationbands indicatesthepresenceofspecicantibodiesto H.capsulatum incase-patientsera. Statisticalmethods. Toevaluatedifferencesinthepotentialriskfactors,univariateanalysiswasdoneusingchisquare.Toidentifyindependentassociations,multivariate analysiswasdoneusinglogisticregressionincludingthose variablesthatweresignicantintheunivariateanalysisand potentialconfoundingvariables.RESULTSCasending. Twohundredtwenty-one(36%)ofthe620 conventionparticipantsrespondedtothemailedsurvey.In additiontotheinitialfourcases,14conrmedandsixsuspectcasesweredetectedresultingin18of24suspectcases beingconrmedbyserology.Ahistogramoftheoutbreak isshowninFigure1.Twenty-two(92%)ofthe24casepatientshadexploredoneoftwocaves,referredtoasCaves AandB.NoneofthosepeopleenteringCaveAentered CaveBandvice-versa.EachofthegroupsenteringCaveA andCaveBhadateamleader.Fromtheseteamleadersand teamparticipants,completelistsofthosewhoenteredCave AorCaveBweregenerated.SixteenpeopleenteredCave Aand13peopleenteredCaveB.Twelveof16attendees enteringCaveAand10of13exploringCaveBdeveloped histoplasmosis,givingcave-specicattack-ratesof75%and 71%,respectively.Therangeofincubationperiods,from caveexposuretoonsetofsymptoms,was10daysfor symptomaticparticipants.Allcasepatientswerepreviously healthy,andreportednothavingenteredothercavesinthe onemonthbeforetheNationalSpeleologicalSocietyconvention.Allpatientsexhibitedfever,chills,headache,and coughofatleasttwo-weeksduration.Coughandfatigue persistedfor12weeksinthreepatients.Eighteenofthe24 case-patientssoughtmedicalattentionasaresultoftheir illness;ofthese,themeantimetodiagnosisafterrstseekingmedicalattentionwasthreeweeks.Bacterialbronchitis orpneumoniawasthemostcommoninitialdiagnosis.Sixteen(89%)ofthe18patientswhosoughtmedicalattention weretreatedwithantibacterialtherapy. Case-controlstudy. Of19cavesenteredduringconventionactivities,twocavesweresignicantlyassociatedwith acutehistoplasmosis:CaveA(oddsratio[OR]513.3,95% condenceinterval[CI]53.260.2)andCaveB(OR512.9,95%CI52.769.2). Cohortstudy. Table1showstheanalysisofriskfactors amongthosecaversenteringCaveAorCaveB.Amongthe cohortofthosepeopleenteringthehighrisk-caves,younger

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901HISTOPLASMOSISOUTBREAKINTEXASTABLE1 Riskfactors*associatedwithhistoplasmosisamongcaverswhoenteredCaveAorCaveBbyunivariateanalysis Variable Cases (n522) Non-cases (n58)RR95%CI P Malesex(%) Meanage(range) Smoke(%) Yearscaving,mean(range) Historyofhistoplasmosis(%) 15(68) 29(1843) 3(14) 10(2) 2(9) 5(63) 44(3262) 1(13) 22(2) 0 0.9 NA 0.8 NA Undened 0.3.5 NA 0.16.5 NA Undened NS#0.05 NS#0.05 NS Hoursincave,mean(range) Rappeledincave(%) Sawbats(%) Touchedguano(%) InCaveAonly(12cases,4non-cases) enteredlongtunnel(%) 5.16(2) 13(59) 21(95) 21(95) 11(92) 2.16(0.5) 4(50) 6(75) 7(86) 1(25) NA 1.1 2.3 1.5 3.3 NA 0.7.7 0.5.7 0.46.1 1.1.2#0.05 NS NS NS#0.05 *NocaveexplorersenteringCaveAorCaveBusedmasksorreportedimmunocompromisingconditions(includingHIV/AIDS). RR5riskratio;CI5condenceinterval;NS5notsignicant;NA5notapplicable.Riskratioswerenotcalculatedforcomparisonofmeans. SeeschematicofCaveA(Figure2). FIGURE2.SchematicofCaveAshowingthenarrowtunnelassociatedwithdevelopmentofhistoplasmosisamongparticipantsat theNationalSpeleologicalSocietyConvention.Thisisalateral view.age,feweryearsofcavingexperience,andmorehoursspent inthecavewereallassociatedwithacquiringacutehistoplasmosis( p#0.05).InCaveA,diseasewasassociated withcrawlingintoorbeyondanarrowtunnel(Figure2).No caveexplorersreportedusingmasksduringtheconvention. NoneofthosecaversenteringCavesAandBreportedhavingapre-existingillnessorcondition(diabetes,cancer,humanimmunodeciencyvirus/AIDSorotherimmunocompromisingcondition)orreceivingsteroidtherapy,which mightpredisposethemtoacutehistoplasmosis.Thesexof thecaverwasnotfoundtobeariskfactorfordisease. Skintestsurvey. Ofthe228TexasCaver'sAssociation reunionparticipants,113(50%)participatedintheseparate skintestsurvey.Ofthose,68(60%)wereskintestpositive (induration.5mm).Five(4%)ofthe113participantshad serologicevidenceofrecentinfectionwith H.capsulatum andsymptomsconsistentwithacutehistoplasmosis.Results ofamultivariateanalysisofriskfactorsforinfectionare showninTable2.Skintestreactivitywassignicantlyassociatedwithmales(OR51.5,95%CI51.1.5)andwith moreyearsofcavingexperience(OR51.8per10-year increment,95%CI51.2.6).Ofrespondents,68(63%) reportedneverhavingusedamaskintheircavingexperience.DISCUSSIONAswehaveshown,exposureto H.capsulatum during cavingmaybeassociatedwithsignicantmorbidity.Alack ofawarenessofhistoplasmosisamongcaversmayincrease theriskofinfectionanddelaythemseekingmedicalattentionifsymptomsdevelop.Thecontinuedreportingofcaveassociatedoutbreakssuggeststhatcurrentpracticeamong caverscontinuestoplacethematriskforthispotentially seriousinfection.Thedatafromourinvestigationsuggest thatduringtheNationalSpeleologicalSocietyConvention inBrackettville,Texas,acutehistoplasmosiswasassociated withexposuretotwocaves.Findingsfromourcohortstudy suggestthatyoungerageandfeweryearsofcavingexperiencemayberiskfactorsforthedevelopmentofacutehistoplasmosisamongcavers.Thesetwovariablesarecorrelated,andonlyfeweryearsofcavingexperienceremainedindependentlyassociatedwithinfectioninmultivariateanalysisamongtheskintestsurveyparticipants.Multivariate analysiswasnotperformedinthecohortstudyofthoseenteringCavesAandB.Also,inthecohortstudy,wefound thatlongertimespentinthecaveswassignicantlyassociatedwithacquiringthisinfection.Whilethissuggestsa doseresponse,ithasbeenpreviouslynotedthathistoplasmosishasdevelopedinindividualswhosesoleexposurewas merelystandingattheentrancetocaves.4Asinotherstudies,1,6,15diagnosiswasdelayedamong thoseconventionattendeeswhodevelopedillness.Inaddition,healthcareprovidersmayfailtoconsiderthediagnosis. Althoughhistoplasmosisisoftenamilddisease,delayin diagnosisofseverecasesmayincreasethelikelihoodofhospitalizationandseverecomplications.1Thisoutbreakwasdetectedbyanastuteclinicianwhonoticedthecorrelationwith cavingamongafewofhispatients.Thefactthatcave-associatedepidemicsareinfrequentlyreported4maybedueto alackofrecognitionbyphysiciansandatendencytoward mildillness.However,becauseofincreasingnumbersof cavers,histoplasmosismaybecomemorecommonasarecreationaldisease.Inaddition,severityofsymptomaticillness mayberelatedtointensityofexposure,andinthiscase, bothCavesAandBwereheavilyinfestedwithbats.EnteringanarrowtunnelinCaveA,whichwasapproximatelya meterindiameter,wasassociatedwithacquiringhistoplas-

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902ASHFORDANDOTHERSTABLE2 Multivariateanalysisofariskfactorsforinfectionamongparticipantsintheskin-testsurvey,TexasCaver'sAssociationreunion* VariableCases(n571)Controls(n542)OR95%CI P Malesex(%) Meanage(range) Smoke(%) Yearscaving,mean(range) Hourscavingpreviousyear,mean(range) Historyofhistoplasmosis(%) Liveinendemicdiseasestate 52(73) 40(18) 13(18) 15(0.1) 179(0,000) 6(8) 15 22(52) 35(1844) 7(17) 9(0.1) 64(0400) 1(2) 6 1.5 0.9 1.2 1.8 3.1 1.4 1.4 1.1.5 0.8.1 0.4.4 1.2.6 0.5.9 0.4.9 0.5.2#0.05 NS NS#0.05 NS NS NS *OR5oddsratio;CI5condenceinterval;NS5notsignicant. StatesalongtheMississippiandOhioRiverValleysintheUnitedStates.mosis.Thetunnelwasreportedtobedryanddustyatthe timeoftheconvention. Forhistoplasmosis,certainriskfactorspredisposeindividualstodevelopmoreseriousdisease.Thelikelihoodofrequiringhospitalizationorofdyingincreasesforapatient withapre-existingimmunocompromisingconditionortherapy.16,17SuchriskfactorsareincreasingamongtheUnited Statespopulationingeneralbecauseofanincreaseinthe useofimmunocompromisingmedicationsandthespreadof theHIVepidemic.Althoughyouthandinexperiencewere foundtoberiskfactorsinourstudy,thenumbersofcavers reportingpre-existingconditionswereinsufcienttoassess differencesintheoccurrenceoftheseconditionsbetween patientsandcontrols.However,becausethisisagenerally healthyandactivepopulation,thehighrateofdiseasefound inthisoutbreakismorelikelytobeduetointenseexposure inthecaves. Thendingof60%skintestpositivityintheTexasCavingAssociationsurveysuggeststhathistoplasmosisismore prevalentamongcaversthanthe31%ratepreviouslyreportedinanationalhistoplasminskintestsurveyofnaval recruitswhogavetheirstateoforiginasTexas.18Johnson andothersfoundahistoplasminskintestsensitivityof4.3% forruralresidentswholivednearcavesinFloridabutaskin testsensitivityof64%amongcaversfromthesamearea.19InSouthAfrica,Murrayandothersreportedaskintestpositivityrateof94.5%forcavers.20Also,oldercaversmaybe morelikelytohavepositiveskintestreactions,reecting pastexposureto H.capsulatum, anditisknownthatinfectionwith H.capsulatum providespartialimmunitytoreinfection.15Only63%ofcaverssurveyedreportedhavingeverused amask,andofallthecaversenteringthehighriskcaves, noneusedamask.Althoughnostudieshaveshownthat maskswouldpreventexposureduringcaving,thedust-mist respiratorsnowrecommendedforuseinhospitalsfortuberculosiscontrolhavethecapacitytolterparticlesof1 microns,whichisthesizeof H.capsulatum spores.21Preventivemeasuresshouldbeinvestigatedtodecreasetherisk ofhistoplasmosisamongcaveexplorers,inparticular,educationofcaversanduseofappropriatemasksincaves.Speciccontrolmeasuresinstitutedfollowingourinvestigation includedpublishingareportofthecavesinvolvedinthe monthlynewsletteroftheNationalSpeleologicalAssociationandpostingwarningsignsatthecaves.Routineculture ofsoilsamplesfromcavesisnotrecommendedbecause H. capsulatum maybefoundinsoilwithoutanassociationwith disease.Decontaminationofcavesisnotfeasibleordesirablebecausebatpopulationsmaybeaffected.Toourknowledge,theeffectivenessofchemoprophylaxisforcaversenteringhigh-riskcaveshasnotbeenstudied.However,cavers andtheirassociationsshouldexpandtheirsurveillanceand reportingsystems,notifymembersabouthigh-riskcaves, andeducateyoungandrecentmembersabouttherisksof histoplasmosisassociatedwithcaving.Healthcareproviders shouldincludequestionsregardingenvironmentalexposure tobirdorbatguano,includingcaving,wheninterviewing patientswithsymptomsofacutebronchitisorpneumonia thatmaybecompatiblewithhistoplasmosis.Acknowledgments:WethanktheTexasDepartmentofHealthfor eldsupport. Disclaimer:UseoftradenamesandcommercialsourcesisforidenticationonlyanddoesnotimplyendorsementbytheU.S.Public HealthServiceortheU.S.DepartmentofHealthandHumanServices. Authors'addresses:DavidA.Ashford,RanaA.Hajjeh,LeoKaufmann,LoriHutwagner,andMichaelM.McNeil,Meningitisand SpecialPathogensBranch,CentersforDiseaseControlandPrevention,MailstopC-23,1600CliftonRoad,Atlanta,GA30333.MichaelF.Kelley,CommunicableDiseaseControl,TexasDepartment ofHealth,Austin,TX78756.REFERENCES1.WheatLJ,SlamaTG,EitzenHE,KohlerRB,FrenchMLV, BieseckerJL,1981.Alargeurbanoutbreakofhistoplasmosis: clinicalfeatures. AnnInternMed94: 331. 2.DeanG,1957.Cavedisease. CentAfrJMed3: 79. 3.WashburnAM,TuohyJH,DavisAL,1948.Cavesicknessa newdiseaseentity? AmJPublicHealth38: 1521. 4.SacksJJ,AjelloL,CrockettLK,1986.Anoutbreakandreview ofcaveassociatedhistoplasmosiscapsulati. JMedVetMycol 24: 313. 5.CentersforDiseaseControlandPrevention,Atlanta,Georgia, 1997. Histoplasmosis:ProtectingWorkersatRisk. PublicationNo.97. 6.BartlettPC,VonbehrenLA,TewariRP,MartinRJ,EagletonL, IsaacMJ,KulkarniPS,1982.Batsinthebelfry:anoutbreak ofhistoplasmosis. AmJPublicHealth72: 1369. 7.CarvajalZamoraJL,1977.Isolationof Histoplasmacapsulatum fromtissuesofbatscapturedintheAguasBuenascaves, AguaBuenas,PuertoRico. Mycopathologia60: 167. 8.McMurrayDN,RussellLH,1982.Contributionofbatstothe maintenanceof Histoplasmacapsulatum inacavemicrofocus. AmJTropMedHyg31: 527. 9.KajihiroES,1965.Occurrenceofdermatophytesinfreshbat guano. ApplMicrobiol13: 720. 10.EmmonsCW,1958.Associationofbatswithhistoplasmosis. PublicHealthRep73: 590. 11.DiSalvoAF,AjelloL,PalmerJW,WinklerWG,1969.Isolation

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903HISTOPLASMOSISOUTBREAKINTEXASof Histoplasmacapsulatum fromArizonabats. AmJEpidemiol89: 606614. 12.GordonMA,ZimentI,1967.Epidemicofacutehistoplasmosis inwesternNewYorkState. NYJMed67: 235. 13.HoffGL,BiglerWJ,1981.Theroleofbatsinthepropagation andspreadofhistoplasmosis:areview. JWildlDis17: 191 196. 14.KaufmanL,KovacsJA,ReissE,1997.ClinicalImmunomycology. ManualofClinicalImmunology. Fifthedition.Washington,DC:AmericanSocietyforMicrobiology,585604. 15.GoodwinRA,DezPrezRM,1978.Histoplasmosis. AmRev RespirDis117: 929. 16.WheatLJ,SlamaTG,NortonJA,KohlerRB,EitzenHE,French MLV,SathapatayavongsB,1982.Riskfactorsfordisseminatedhistoplasmosis. AnnInternMed96: 159. 17.NightingaleSD,ParksJM,PoundersSM,BurnsDK,Reynolds J,HernandezJA,1990.DisseminatedhistoplasmosisinpatientswithAIDS. SouthMedJ83: 624630. 18.EdwardsPQ,KlaerJH,1957.Worldwidedistributionofhistoplasmosisandhistoplasmosissensitivity. AmJTropMedHyg 5: 235. 19.JohnsonJE,RadimerG,DisalvoAF,AjelloL,BiglerW,1970. HistoplasmosisinFlorida.I.Reportofacaseandepidemiologicstudies. AmRevRespirDis101: 299. 20.MurrayJF,LurieHI,KayeJ,KominsC,BorokR,WayM,1957. Benignpulmonaryhistoplasmosis(cavedisease)inSouthAfrica. SouthAfrMedJ31: 245. 21.CentersforDiseaseControlandPrevention,1994.Guidelines forpreventingtransmissionof Mycobacteriumtuberculosis in health-carefacilities. MMWRMorbMortalWklyRep43(RR13): 1.


Description
DAVID A. ASHFORD, RANA A. HAJJEH, MICHAEL F. KELLEY, LEO
KAUFMAN, LORI HUTWAGNER, AND MICHAEL M. McNEIL Meningitis and
Special Pathogens Branch, Division of Bacterial and Mycotic
Diseases, National Center for Infectious Diseases, Centers
for Disease Control and Prevention, Atlanta, Georgia;
Communicable Disease Control, Texas Department of Health,
Austin, Texas Abstract. In June 1994, 18 people developed
serologically confirmed histoplasmosis following cave
exploration associated with the annual National Speleological
Society Convention in Bracketville, Texas. Six others had an
undiagnosed illness suspected to be histoplasmosis. Two
persons were hospitalized. We conducted a survey of con-
vention attendees and a nested case-control study of those
entering caves. We also conducted a histoplasmin skin test
survey of a subgroup of the society, the Texas Cavers
Association, who were attending a reunion in October 1994.
Among the national convention attendees, exposure to two
caves was identified as responsible for 22 (92%) of the 24
cases; 12 (75%) of 16 people exploring one cave (Cave A) and
10 (77%) of 13 exploring a separate cave (Cave B) developed
acute histoplasmosis. Additional risk-factors included fewer
years of caving experience, longer time spent in the caves,
and entering a confined crawl space in Cave A. Of 113
participants in the separate skin test survey, 68 (60%) were
found to be skin test positive, indicating previous exposure
to Histoplasma capsulatum. A positive skin test was
significantly associated with male sex and more years of
caving experience. Those less experienced in caving
associations should be taught about histoplasmosis, and
health care providers should pursue histories of cave
exposure for patients with bronchitis or pneumonia that does
not respond to initial antibiotic therapy.