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. 2015 Nov;53(11):3663-6.
doi: 10.1128/JCM.01680-15. Epub 2015 Sep 9.

Optimal Cutoff Titers for Indirect Immunofluorescence Assay for Diagnosis of Scrub Typhus

Free PMC article

Optimal Cutoff Titers for Indirect Immunofluorescence Assay for Diagnosis of Scrub Typhus

Cherry Lim et al. J Clin Microbiol. .
Free PMC article


We determined the optimal cutoff titers in admission and convalescent-phase samples for scrub typhus indirect immunofluorescence assay using Bayesian latent class models. Cutoff titers of ≥1:3,200 in an admission sample or of a ≥4-fold rise to ≥1:3,200 in a convalescent-phase sample provided the highest accuracy (sensitivity, 81.6%; specificity, 100%).


Unbiased receiver operating characteristic (ROC) curves using Bayesian latent class models (LCMs) for all possible cutoff titers of admission IFA IgM in an admission sample alone (A) and for IFA IgM of either ≥1:3,200 (B), ≥1:1,600 (C), ≥1:800 (D), and ≥1:400 (E) in an admission sample or a ≥4-fold rise to various cutoff titers in a convalescent-phase sample.

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