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RockyMountainSpottedFever(RMSF) ByMeganHietpas EtiologicAgent:Rickettsiarickettsii(7) Transmission:HumansareinfectedwithRickettsiarickettsiithoughthebiteofaninfected.(1) Reservoirs:Ticks.SometickspeciesknownforcarryingthisdiseasearetheAmericandogtick, theRockyMountainwoodtick,andthebrowndogtick.(1) Rickettsiarickettsiicharacteristics:Gram-negativecoccobacilli.0.3-0.5µmx0.8-2.0µm. Aerobic.Obligateintracellularparasite.(2) SignsandSymptoms:Suddenonsetfever,severeheadache,fatigue,musclepain,chills,and petechialrash.Thefirstsymptomsusuallystart5-10daysafterthetickbite.Therashtypically beginstoappear2-5daysafterthefirstsymptomsanddoesnotmanifestasthetypicalrashof small,redspotsuntilabouta7days.Other,lesscommonsymptoms(listedleastcommonto mostcommon)includegangrene,seizures,coma,jaundice,ataxia,lethargy,orconfusion.(3,5, 7)Duetothevarianceinthesymptomsofthisdisease,itisoftendifficulttodiagnose.Some patientsneverevendeveloptherash.(1) KeyTests:Testscanonlybedefinitiveaftertheantibodieshavedeveloped.Theteststhatcan beperformedincludeagglutination,complementfixation,indirectimmunofluorescenceassay (IFA),EIA,Westernblot,andNAT.(9)Aninfectedpatient’simmunesystemwillproduce antibodiesagainstR.rickettsiiandthesecanbetestedforaboutaweekafterthebeginningof theinfection.ThepreferredtestfortheseantibodiesistheIFA.Thistestcomparestwosamples ofthepatient’sserumtoseeiftherewasalargeincreaseinIgGlevels.Thefirstsampleshould betakenasearlyintotheillnessaspossibleandthesecondshouldbetaken2-4weekslater.(1) Historicalinformation:Boise,Idaho,1896,R.rickettsiiwasfirstidentifiedasadiseasebyMajor MarshallH.Wood.Thefirstmedicalcasewasreportedin1899regardingandinfectedperson fromtheSnakeRiverValleyinIdaho.Thenin1902,inBitterrootValley,Montana,7peopledied fromRMSF.R.rickettsiiwasnamedafterHowardRicketts.HestudiedRMSFandidentifiedthe etiologicagentandmethodoftransmissionin1906.R.rickettsiiwasidentifiedasan intracellularpathogenbyS.BurtWolbachin1919.(7)ThefirsttestforRMSFwastheWeil-Felix testanditwasfirstavailablein1921.(9) VirulenceFactors:R.rickettsiahasaproteininitsoutermembranecalledOmpAwhichaidsin adherence,thefirststepinaninfection.R.rickettsiaappearstobeabletocauseahostcellsto performphagocytosis.Thisgetstheorganismintothehostcellwhereiswillavoidphagocytosis andmoveintothecytoplasm.R.rickettsiadoesnotlysethehostcellbutinsteadtheyemerge fromthehostcell’smembrane.Thereisdamagedonetothehostcellbutitisnotclearwhat exactlycausesthisdamage.(11) Treatment:ThetreatmentusedforRMSFdependsontheseverityofthecase.Antibioticsthat canbeusedincludedoxycycline,tetracycline,andchloramphenicol.Ifleftuntreated,this diseasecouldbefatal.(6)Iftheinfectionisnotcaughtearlyorifitisamoresevereinfection, thepatientmayrequirehospitalizationandintravenousantibiotics.Becausethisdiseaseis difficulttodiagnose,doctorsmustusetheirbestjudgementandapatient’srecenthistoryto assumethatthepatientactuallyhasRMSFandtheyshouldbestartedonantibiotics. Doxycyclineisthepreferredantibioticandshouldbestartedwithinthefirstfivedaysafterthe symptomshavestarted.Ifapatientdoesn’trespondtothisantibiotic,theyprobablydonot haveRMSF.(1) Prevention:Ifapersonfindsthemselvesinanareawhereticksareknowntolive,theyshould wearclothesthatcoverasmuchofyourskinaspossible.Lightcoloredclothingisalso recommended.Thiswillpreventtheticksfromgainingaccesstoyouskin,whichisobviously thebestdefense.ApplyinginsectrepellentcontainingDEETwillrepeltickandstayingonpaths ratherthangoingthroughheavilywoodedareasisagoodwaytoavoidcomingincontactwith ticks.Aftercomingbackindoorsforthedayyoushouldcheckyourentirebodyforticks,evenif youhaveworntheaforementionedclothing.Itisalsoagoodideatotakeashowertowashany unattachedticksoffyourbody.(4) LocalCases:CaseshavebeenreportedinallstatesexceptforVermontandHawaii,butRMSFis mostcommoninruralandsuburbanlocationsintheSoutheast,westernSouthCentral,and partsoftheNortheastregionsoftheUnitedStates.RMSFmostcommonlyoccursinthe summermonths.Thenumbersofrecordedcaseshavefluctuatedgreatlysince1920.For example,2005had1,936reportedcaseswhile1998had365.(8)Thenumberofcasesreported eachyearhasusuallyincreasedsince1993to2010.Thepeakwasin2008with2,553cases.(12) GlobalCases:RMSFisonlypresentintheAmericas.(8)Thereisnotmuchdataregarding incidenceoutsideoftheUnitedStatesthough. WorksCited 1. CentersforDiseaseControlandPrevention,RickettsialZoonosesBranch.“Mountain SpottedFever(RMSF);Symptoms,Diagnosis,andTreatment”.September5,2013. http://www.cdc.gov/rmsf/symptoms/index.html#.May3,2016. 2. Todar,Kenneth.“Todar’sOnlineTextbookofBacteriology”.RickettsialDiseases, includingTyphusandRockyMountainSpottedFeverchapter.2012. http://textbookofbacteriology.net/Rickettsia.html.May3,2016. 3. ColumbiaUniversityMedicalCenter.LymeandTick-BorneDiseasesResearchCenter. “RockyMountainSpottedFever”.http://columbialyme.org/patients/tbd_spotted_fever.html.May3,2016. 4. JohnsHopkinsMedicine.HealthLibrary.“RockyMountainSpottedFever”. http://www.hopkinsmedicine.org/healthlibrary/conditions/adult/infectious_diseases/ro cky_mountain_spotted_fever_85,p00645/.May8,2016. 5. Chamberlain,NealR.“SpottedFevers”.March11,2016. https://www.atsu.edu/faculty/chamberlain/website/lectures/tritzid/spotfev.htm.May 8,2016. 6. Walker,DavidH.MedicalMicrobiology.4thedition.1996. http://www.ncbi.nlm.nih.gov/books/NBK7624/.May9,2016. 7. Cunha,BurkeA.“RockyMountainSpottedFever”.October8,2015. http://emedicine.medscape.com/article/228042-overview.May9,2016. 8. Cunha,BurkeA.“RockyMountainSpottedFever”.October8,2015. http://emedicine.medscape.com/article/228042-overview#a6.May9,2016. 9. AABBOrganization.“Rickettsiarickettsii.Appendix2”.August2009. https://www.aabb.org/tm/eid/Documents/184s.pdf.May9,2016. 10. ARUPLaboratories.“Rickettsiarickettsii–RockyMountainSpottedFever”.April2016. https://arupconsult.com/content/rickettsia-rickettsii.May9,2016. 11. Todar,Kenneth.“Todar’sOnlineTextbookofBacteriology”.RickettsialDiseases, includingTyphusandRockyMountainSpottedFeverchapter.2012 http://textbookofbacteriology.net/Rickettsia_2.html.May9,2016. 12. CentersforDiseaseControlandPrevention,RickettsialZoonosesBranch.“Mountain SpottedFever(RMSF);StatisticsandEpidemiology”.September5,2013. http://www.cdc.gov/rmsf/stats/index.html.May9,2016.