Variables affecting laboratory diagnosis of acute rickettsial infection
Cecilia KatoRickettsial Zoonoses Branch
Division of Vector-Borne Diseases
National Center For Emerging and Zoonotic Infectious Diseases
Centers for Disease Control and Prevention
MailStop H17-3
1600 Clifton Road NE
Atlanta, GA 30333, USA
Office: 404.639.0152
Email: ckato@cdc.gov
Microbiology Australia 39(4) 220-222 https://doi.org/10.1071/MA18068
Published: 12 November 2018
Abstract
The reference standard for the confirmation of a recent rickettsial infection is by the observation of a four-fold or greater rise in antibody titres when testing paired acute and convalescent (two to four weeks after illness resolution) sera by serological assays (Figure 1). At the acute stage of illness, diagnosis is performed by molecular detection methods most effectively on DNA extracted from tissue biopsies (eschars, skin rash, and organs) or eschar swabs. Less invasive and more convenient samples such as blood and serum may also be used for detection; however, the low number of circulating bacteria raises the possibility of false negative results. Optimal sampling practices and enhanced sensitivity must therefore be considered in order to provide a more accurate laboratory diagnosis.
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