title: Short report: detection of Orientia tsutsugamushi in clinical samples by quantitative real-time polymerase chain reaction.
abstract: Orientia tsutsugamushi infection causes scrub typhus, a common zoonosis of rural Asia. Orientia tsutsugamushi was recently detected by a real-time quantitative polymerase chain reaction (qPCR) assay in animal specimens. We evaluated the same qPCR assay in specimens obtained from patients with serologically proven scrub typhus infections. The 47-kDa qPCR assay was more sensitive than was mouse inoculation; it was reactive in whole blood specimens from all 10 isolate-positive patients and in 7 of 17 isolate-negative individuals (P = 0.003, Fisher's two-tailed exact test). As few as 1,076 O. tsutsugamushi copies/microL were detected in whole blood. Four of 7 sera from isolate-proven scrub typhus infections were also reactive by qPCR. The assay was unreactive in all 12 individuals without scrub typhus infection. This is the first demonstration of a sensitive and specific real-time qPCR assay for human scrub typhus infection.
authors.affiliation: Department of Clinical Tropical Medicine, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand. tmtss@mahidol.ac.th
authors.forename: Tasawan
authors.initials: T
authors.lastname: Singhsilarak
authors.forename: Wattana
authors.initials: W
authors.lastname: Leowattana
authors.forename: Sornchai
authors.initials: S
authors.lastname: Looareesuwan
authors.forename: Varee
authors.initials: V
authors.lastname: Wongchotigul
authors.forename: Ju
authors.initials: J
authors.lastname: Jiang
authors.forename: Allen L
authors.initials: AL
authors.lastname: Richards
authors.forename: George
authors.initials: G
authors.lastname: Watt
mesh_terms: D004269:DNA, Bacterial / Q000032:analysis; D006801:Humans; D012285:Orientia tsutsugamushi / Q000302:isolation & purification*; D016133:Polymerase Chain Reaction / Q000379:methods*; D012612:Scrub Typhus / Q000175:diagnosis*; D012680:Sensitivity and Specificity
chemical_list: D004269:DNA, Bacterial