The expanding spectrum of eschar-associated rickettsioses in the United States.
BACKGROUND
Until recently, Rickettsia rickettsii was the only substantiated cause of tick-borne spotted fever group (SFG) rickettsiosis in humans in the United States. Rickettsia parkeri, originally thought to be nonpathogenic in humans, was recently proved to be another cause of tick-borne SFG rickettsiosis.


METHODS
We report 3 cases of SFG rickettsiosis and discuss the epidemiology, clinical presentation, histopathologic features, and laboratory findings that support confirmed or probable diagnoses of R parkeri infection and describe the expanding list of eschar-associated SFG rickettsioses recognized in US patients.


CONCLUSIONS
The SFG rickettsioses share many clinical manifestations and extensive antigenic cross-reactivity that may hamper specific confirmation of the causative agent.
Cragun
W Chad
WC
Dermatology Service, San Antonio Military Medical Center, 2200 Bergquist Dr, Ste 1, Lackland AFB, TX 78236-9908, USA. chad.cragun@us.army.mil
Bartlett
Brenda L
BL
Ellis
Michael W
MW
Hoover
Aaron Z
AZ
Tyring
Stephen K
SK
Mendoza
Natalia
N
Vento
Todd J
TJ
Nicholson
William L
WL
Eremeeva
Marina E
ME
Olano
Juan P
JP
Rapini
Ronald P
RP
Paddock
Christopher D
CD
D000328:Adult; D000907:Antibodies, Bacterial / Q000032:analysis*; D001706:Biopsy; D003937:Diagnosis, Differential; D019353:Endemic Diseases; D006801:Humans; D008297:Male; D008875:Middle Aged; D012284:Rickettsia rickettsii / Q000276:immunology* / Q000302:isolation & purification; D012373:Rocky Mountain Spotted Fever / Q000175:diagnosis* / Q000453:epidemiology / Q000382:microbiology; D012867:Skin / Q000382:microbiology / Q000473:pathology*; D013781:Texas / Q000453:epidemiology
D000907:Antibodies, Bacterial