title: Inadequacy of IgM antibody tests for diagnosis of Rocky Mountain Spotted Fever.
abstract: Among 13 suspected Rocky Mountain spotted fever (RMSF) cases identified through an enhanced surveillance program in Tennessee, antibodies to Rickettsia rickettsii were detected in 10 (77%) patients using a standard indirect immunofluorescent antibody (IFA) assay. Immunoglobulin M (IgM) antibodies were observed for 6 of 13 patients (46%) without a corresponding development of IgG, and for 3 of 10 patients (30%) at least 1 year post-onset. However, recent infection with a spotted fever group rickettsiae could not be confirmed for any patient, based on a lack of rising antibody titers in properly timed acute and convalescent serologic specimens, and negative findings by polymerase chain reaction testing. Case definitions used in national surveillance programs lack specificity and may capture cases that do not represent current rickettsial infections. Use of IgM antibodies should be reconsidered as a basis for diagnosis and public health reporting of RMSF and other spotted fever group rickettsiae in the United States.
authors.affiliation: Rickettsial Zoonoses Branch, Division of Vectorborne Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia; Tennessee Department of Health, Nashville, Tennessee fzh7@cdc.gov.
authors.forename: Jennifer H
authors.initials: JH
authors.lastname: McQuiston
authors.affiliation: Rickettsial Zoonoses Branch, Division of Vectorborne Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia; Tennessee Department of Health, Nashville, Tennessee.
authors.forename: Caleb
authors.initials: C
authors.lastname: Wiedeman
authors.affiliation: Rickettsial Zoonoses Branch, Division of Vectorborne Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia; Tennessee Department of Health, Nashville, Tennessee.
authors.forename: Joseph
authors.initials: J
authors.lastname: Singleton
authors.affiliation: Rickettsial Zoonoses Branch, Division of Vectorborne Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia; Tennessee Department of Health, Nashville, Tennessee.
authors.forename: L Rand
authors.initials: LR
authors.lastname: Carpenter
authors.affiliation: Rickettsial Zoonoses Branch, Division of Vectorborne Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia; Tennessee Department of Health, Nashville, Tennessee.
authors.forename: Kristina
authors.initials: K
authors.lastname: McElroy
authors.affiliation: Rickettsial Zoonoses Branch, Division of Vectorborne Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia; Tennessee Department of Health, Nashville, Tennessee.
authors.forename: Emily
authors.initials: E
authors.lastname: Mosites
authors.affiliation: Rickettsial Zoonoses Branch, Division of Vectorborne Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia; Tennessee Department of Health, Nashville, Tennessee.
authors.forename: Ida
authors.initials: I
authors.lastname: Chung
authors.affiliation: Rickettsial Zoonoses Branch, Division of Vectorborne Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia; Tennessee Department of Health, Nashville, Tennessee.
authors.forename: Cecilia
authors.initials: C
authors.lastname: Kato
authors.affiliation: Rickettsial Zoonoses Branch, Division of Vectorborne Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia; Tennessee Department of Health, Nashville, Tennessee.
authors.forename: Kevin
authors.initials: K
authors.lastname: Morris
authors.affiliation: Rickettsial Zoonoses Branch, Division of Vectorborne Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia; Tennessee Department of Health, Nashville, Tennessee.
authors.forename: Abelardo C
authors.initials: AC
authors.lastname: Moncayo
authors.affiliation: Rickettsial Zoonoses Branch, Division of Vectorborne Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia; Tennessee Department of Health, Nashville, Tennessee.
authors.forename: Susan
authors.initials: S
authors.lastname: Porter
authors.affiliation: Rickettsial Zoonoses Branch, Division of Vectorborne Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia; Tennessee Department of Health, Nashville, Tennessee.
authors.forename: John
authors.initials: J
authors.lastname: Dunn
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000907:Antibodies, Bacterial / Q000097:blood*; D015331:Cohort Studies; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood*; D007075:Immunoglobulin M / Q000097:blood*; D008875:Middle Aged; D012284:Rickettsia rickettsii / Q000276:immunology* / Q000302:isolation & purification; D012373:Rocky Mountain Spotted Fever / Q000175:diagnosis* / Q000453:epidemiology; D013714:Tennessee / Q000453:epidemiology; D055815:Young Adult
chemical_list: D000907:Antibodies, Bacterial; D007074:Immunoglobulin G; D007075:Immunoglobulin M
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