Download Rocky Mountain Spotted Fever (RMSF)

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.