Rocky Mountain spotted fever (RMSF) is the most severe tick-borne rickettsial illness in the United States. There are 250 to 1200 cases reported annually in the ...Health311SearchallNYC.govwebsitesMenuPromotingandProtectingtheCity'sHealthText-SizeSearchPromotingandProtectingtheCity'sHealthHomeCOVIDAboutOurHealthServicesProvidersDataBusinessSearchSearchHealthTopicsNeighborhoodHealthEmergencyPrepPublicationsSharePrintRockyMountainSpottedFever(Tick-borneTyphusFever)WhatisRockyMountainspottedfever?RockyMountainspottedfever(RMSF)isthemostseveretick-bornerickettsialillnessintheUnitedStates.Thereare250to1200casesreportedannuallyintheUS.ItisazoonoticdiseasecausedbythebacteriumRickettsiaricketsii.MostcasesofRMSFoccurinthesoutheasternandsouthcentralUnitedStates.RMSFistransmittedtohumansandotheranimalsbythebiteofaninfectedtick.Tickscanbecomeinfectedbyfeedingoninfectedanimalhosts.However,onceinfected,anadulttickcanpasstheinfectiontoitsoffspring.IntheUnitedStates,eastoftheRockyMountainsandalongthePacificcoast,theprimaryvectoristheAmericandogtick,Dermacentorvariabilis.IntheRockyMountainregion,theRockyMountainwoodtick,Dermacentorandersoni,istheprimaryvectorspecies.Otherticks,particularlythelonestartick,Amblyommaamericanum,mayoccasionallytransmitRMSF.Person-to-personspreadofRMSFdoesnotoccur.ItusuallytakesseveralhoursofattachmentbeforeaninfectedtickcantransmitRMSFbacteria.RockyMountainspottedfeverinNewYorkCityNationally,thediseaseisreportedlymostcommoninchildrenunder10yearsofage,butinNYCthemajorityofpatientsaremiddle-aged.ThenumberofcasesreportedinNYChasrangedfrom2to27peryear.FormoreinformationonthenumberofNYCresidentsreportedtohaveRMSF,pleasevisitEpiQuery.TheAmericandogtickcanbefoundinallfiveboroughsofNewYorkCity,aswellasnearlyallparksandwoodlandsintheeasternUnitedStates.In1996,anoutbreakofRMSFoccurredinNewYorkCity,primarilyintheregionofSoundviewParkintheBronx.However,casesofRMSFhaveoccurredinallfiveboroughs.Adultdogtickswillfeedonpeople,andaremostactiveduringthespring,summer,andfa