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Am J Trop Med Hyg. 2014 Oct;91(4):767-70. doi: 10.4269/ajtmh.14-0123. Epub 2014 Aug 4.

Inadequacy of IgM antibody tests for diagnosis of Rocky Mountain Spotted Fever.

Author information

1
Rickettsial Zoonoses Branch, Division of Vectorborne Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia; Tennessee Department of Health, Nashville, Tennessee fzh7@cdc.gov.
2
Rickettsial Zoonoses Branch, Division of Vectorborne Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia; Tennessee Department of Health, Nashville, Tennessee.

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.

PMID:
25092818
PMCID:
PMC4183402
DOI:
10.4269/ajtmh.14-0123
[Indexed for MEDLINE]
Free PMC Article

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