title: A prospective evaluation of real-time PCR assays for the detection of Orientia tsutsugamushi and Rickettsia spp. for early diagnosis of rickettsial infections during the acute phase of undifferentiated febrile illness.
abstract: One hundred and eighty febrile patients were analyzed in a prospective evaluation of Orientia tsutsugamushi and Rickettsia spp. real-time polymerase chain reaction (PCR) assays for early diagnosis of rickettsial infections. By paired serology, 3.9% (7 of 180) and 6.1% (11 of 180) of patients were confirmed to have acute scrub or murine typhus, respectively. The PCR assays for the detection of O. tsutsugamushi and Rickettsia spp. had high specificity (99.4% [95% confidence interval (CI): 96.8-100] and 100% [95% CI: 97.8-100], respectively). The PCR results were also compared with immunoglobulin M (IgM) immunofluorescence assay (IFA) on acute sera. For O. tsutsugamushi, PCR sensitivity was twice that of acute specimen IgM IFA (28.6% versus 14.3%; McNemar's P = 0.3). For Rickettsia spp., PCR was four times as sensitive as acute specimen IgM IFA (36.4% versus 9.1%; P = 0.08), although this was not statistically significant. Whole blood and buffy coat, but not serum, were acceptable specimens for these PCRs. Further evaluation of these assays in a larger prospective study is warranted.
authors.forename: Wanitda
authors.initials: W
authors.lastname: Watthanaworawit
authors.forename: Paul
authors.initials: P
authors.lastname: Turner
authors.forename: Claudia
authors.initials: C
authors.lastname: Turner
authors.forename: Ampai
authors.initials: A
authors.lastname: Tanganuchitcharnchai
authors.forename: Allen L
authors.initials: AL
authors.lastname: Richards
authors.forename: Kevin M
authors.initials: KM
authors.lastname: Bourzac
authors.forename: Stuart D
authors.initials: SD
authors.lastname: Blacksell
authors.forename: François
authors.initials: F
authors.lastname: Nosten
mesh_terms: D000818:Animals; D005334:Fever; D006801:Humans; D012285:Orientia tsutsugamushi / Q000302:isolation & purification*; D011446:Prospective Studies; D060888:Real-Time Polymerase Chain Reaction / Q000379:methods*; D012281:Rickettsia / Q000302:isolation & purification*; D012282:Rickettsia Infections / Q000175:diagnosis* / Q000382:microbiology; D012612:Scrub Typhus / Q000175:diagnosis* / Q000382:microbiology