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Diagnostic Accuracy of the InBios Scrub Typhus Detect™ ELISA for the Detection of IgM Antibodies in Chittagong, Bangladesh

Here we estimated the accuracy of the InBios Scrub Typhus Detect™ immunoglobulin M (IgM) ELISA to determine the optimal optical density (OD) cut-off values for the diagnosis of scrub typhus. Patients with undifferentiated febrile illness from Chittagong, Bangladesh, provided samples for reference te...

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Autores principales: Blacksell, Stuart D., Kingston, Hugh W. F., Tanganuchitcharnchai, Ampai, Phanichkrivalkosil, Meghna, Hossain, Mosharraf, Hossain, Amir, Ghose, Aniruddha, Leopold, Stije J., Dondorp, Arjen M., Day, Nicholas P. J., Paris, Daniel H.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: MDPI 2018
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6160969/
https://www.ncbi.nlm.nih.gov/pubmed/30274491
http://dx.doi.org/10.3390/tropicalmed3030095
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author Blacksell, Stuart D.
Kingston, Hugh W. F.
Tanganuchitcharnchai, Ampai
Phanichkrivalkosil, Meghna
Hossain, Mosharraf
Hossain, Amir
Ghose, Aniruddha
Leopold, Stije J.
Dondorp, Arjen M.
Day, Nicholas P. J.
Paris, Daniel H.
author_facet Blacksell, Stuart D.
Kingston, Hugh W. F.
Tanganuchitcharnchai, Ampai
Phanichkrivalkosil, Meghna
Hossain, Mosharraf
Hossain, Amir
Ghose, Aniruddha
Leopold, Stije J.
Dondorp, Arjen M.
Day, Nicholas P. J.
Paris, Daniel H.
author_sort Blacksell, Stuart D.
collection PubMed
description Here we estimated the accuracy of the InBios Scrub Typhus Detect™ immunoglobulin M (IgM) ELISA to determine the optimal optical density (OD) cut-off values for the diagnosis of scrub typhus. Patients with undifferentiated febrile illness from Chittagong, Bangladesh, provided samples for reference testing using (i) qPCR using the Orientia spp. 47-kDa htra gene, (ii) IFA ≥1:3200 on admission, (iii) immunofluorescence assay (IFA) ≥1:3200 on admission or 4-fold rise to ≥3200, and (iv) combination of PCR and IFA positivity. For sero-epidemiological purposes (ELISA vs. IFA ≥1:3200 on admission or 4-fold rise to ≥3200), the OD cut-off for admission samples was ≥1.25, resulting in a sensitivity (Sn) of 91.5 (95% confidence interval (95% CI: 96.8–82.5) and a specificity (Sp) of 92.4 (95% CI: 95.0–89.0), while for convalescent samples the OD cut-off was ≥1.50 with Sn of 66.0 (95% CI: 78.5–51.7) and Sp of 96.0 (95% CI: 98.3–92.3). Comparisons against comparator reference tests (ELISA vs. all tests including PCR) indicated the most appropriate cut-off OD to be within the range of 0.75–1.25. For admission samples, the best Sn/Sp compromise was at 1.25 OD (Sn 91.5%, Sp 92.4%) and for convalescent samples at 0.75 OD (Sn 69.8%, Sp 89.5%). A relatively high (stringent) diagnostic cut-off value provides increased diagnostic accuracy with high sensitivity and specificity in the majority of cases, while lowering the cut-off runs the risk of false positivity. This study underlines the need for regional assessment of new diagnostic tests according to the level of endemicity of the disease given the high levels of residual or cross-reacting antibodies in the general population.
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spelling pubmed-61609692018-10-01 Diagnostic Accuracy of the InBios Scrub Typhus Detect™ ELISA for the Detection of IgM Antibodies in Chittagong, Bangladesh Blacksell, Stuart D. Kingston, Hugh W. F. Tanganuchitcharnchai, Ampai Phanichkrivalkosil, Meghna Hossain, Mosharraf Hossain, Amir Ghose, Aniruddha Leopold, Stije J. Dondorp, Arjen M. Day, Nicholas P. J. Paris, Daniel H. Trop Med Infect Dis Article Here we estimated the accuracy of the InBios Scrub Typhus Detect™ immunoglobulin M (IgM) ELISA to determine the optimal optical density (OD) cut-off values for the diagnosis of scrub typhus. Patients with undifferentiated febrile illness from Chittagong, Bangladesh, provided samples for reference testing using (i) qPCR using the Orientia spp. 47-kDa htra gene, (ii) IFA ≥1:3200 on admission, (iii) immunofluorescence assay (IFA) ≥1:3200 on admission or 4-fold rise to ≥3200, and (iv) combination of PCR and IFA positivity. For sero-epidemiological purposes (ELISA vs. IFA ≥1:3200 on admission or 4-fold rise to ≥3200), the OD cut-off for admission samples was ≥1.25, resulting in a sensitivity (Sn) of 91.5 (95% confidence interval (95% CI: 96.8–82.5) and a specificity (Sp) of 92.4 (95% CI: 95.0–89.0), while for convalescent samples the OD cut-off was ≥1.50 with Sn of 66.0 (95% CI: 78.5–51.7) and Sp of 96.0 (95% CI: 98.3–92.3). Comparisons against comparator reference tests (ELISA vs. all tests including PCR) indicated the most appropriate cut-off OD to be within the range of 0.75–1.25. For admission samples, the best Sn/Sp compromise was at 1.25 OD (Sn 91.5%, Sp 92.4%) and for convalescent samples at 0.75 OD (Sn 69.8%, Sp 89.5%). A relatively high (stringent) diagnostic cut-off value provides increased diagnostic accuracy with high sensitivity and specificity in the majority of cases, while lowering the cut-off runs the risk of false positivity. This study underlines the need for regional assessment of new diagnostic tests according to the level of endemicity of the disease given the high levels of residual or cross-reacting antibodies in the general population. MDPI 2018-09-01 /pmc/articles/PMC6160969/ /pubmed/30274491 http://dx.doi.org/10.3390/tropicalmed3030095 Text en © 2018 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).
spellingShingle Article
Blacksell, Stuart D.
Kingston, Hugh W. F.
Tanganuchitcharnchai, Ampai
Phanichkrivalkosil, Meghna
Hossain, Mosharraf
Hossain, Amir
Ghose, Aniruddha
Leopold, Stije J.
Dondorp, Arjen M.
Day, Nicholas P. J.
Paris, Daniel H.
Diagnostic Accuracy of the InBios Scrub Typhus Detect™ ELISA for the Detection of IgM Antibodies in Chittagong, Bangladesh
title Diagnostic Accuracy of the InBios Scrub Typhus Detect™ ELISA for the Detection of IgM Antibodies in Chittagong, Bangladesh
title_full Diagnostic Accuracy of the InBios Scrub Typhus Detect™ ELISA for the Detection of IgM Antibodies in Chittagong, Bangladesh
title_fullStr Diagnostic Accuracy of the InBios Scrub Typhus Detect™ ELISA for the Detection of IgM Antibodies in Chittagong, Bangladesh
title_full_unstemmed Diagnostic Accuracy of the InBios Scrub Typhus Detect™ ELISA for the Detection of IgM Antibodies in Chittagong, Bangladesh
title_short Diagnostic Accuracy of the InBios Scrub Typhus Detect™ ELISA for the Detection of IgM Antibodies in Chittagong, Bangladesh
title_sort diagnostic accuracy of the inbios scrub typhus detect™ elisa for the detection of igm antibodies in chittagong, bangladesh
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6160969/
https://www.ncbi.nlm.nih.gov/pubmed/30274491
http://dx.doi.org/10.3390/tropicalmed3030095
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