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Updated: May 20, 2026
Development of a Lateral Flow Immunochromatographic Strip for Rapid and Quantitative Detection of Small Molecule Compounds
Published on: November 13, 2021
Development of new, broadly reactive, rapid IgG and IgM lateral flow assays for diagnosis of scrub typhus
Saowaluk Silpasakorn1, Nujorn Srisamut, Pattama Ekpo
1Department of Medicine, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand. aowaluk_8@yahoo.com
We evaluated the diagnostic accuracy of two broadly reactive rapid immunochromatographic tests (ICTs) for detection of IgM and IgG against Orientia tsutsugamushi by using archived acute-phase serum samples from 102 patients with laboratory-confirmed scrub typhus, and from 62 archived serum samples from patients with other causes of fever as a negative control. These ICTs were constructed by using a mixture of recombinant proteins: 1) C1, a chimeric protein containing epitopes of the 56-kD antigen from Karp and TA763 strains; 2) Ktr56; and 3) Gmr56. Sensitivities of the ICTs for detection of IgM and IgG were 90.2% (95% confidence interval [CI] = 84.4-96.0%) and 86.3% (95% CI = 80.9-93.8%), respectively. Specificities were 85.5% (95% CI = 73.9-92.2%) and 96.8% (95% CI = 90.3-100%), respectively. Both assays were more sensitive and specific than the standard immune immunofluorescence assay for the early diagnosis of scrub typhus.
We evaluated the diagnostic accuracy of two broadly reactive rapid immunochromatographic tests (ICTs) for detection of IgM and IgG against Orientia tsutsugamushi by using archived acute-phase serum samples from 102 patients with laboratory-confirmed scrub typhus, and from 62 archived serum samples from patients with other causes of fever as a negative control. These ICTs were constructed by using a mixture of recombinant proteins: 1) C1, a chimeric protein containing epitopes of the 56-kD antigen from Karp and TA763 strains; 2) Ktr56; and 3) Gmr56. Sensitivities of the ICTs for detection of IgM and IgG were 90.2% (95% confidence interval [CI] = 84.4-96.0%) and 86.3% (95% CI = 80.9-93.8%), respectively. Specificities were 85.5% (95% CI = 73.9-92.2%) and 96.8% (95% CI = 90.3-100%), respectively. Both assays were more sensitive and specific than the standard immune immunofluorescence assay for the early diagnosis of scrub typhus.
