Diagnostic Validation of Selected Serological Tests for Detecting Scrub Typhus

Koraluru, Munegowda and Bairy, Indira and Varma, Muralidhar D (2015) Diagnostic Validation of Selected Serological Tests for Detecting Scrub Typhus. Microbiology and Immunology, 59. pp. 371-374.

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Clinical diagnosis of scrub typhus is often difficult because the symptomsare very similar to those of other febrile illness such as dengue, leptospirosis, malaria and other viral hemorrhagic fevers. Though better diagnostic tests are available for rickettsial diseases and scrub typhus elsewhere, the Weil–Felix test is still commonly used in India, mainly becausemicroimmunofluorescence assays (M-IFA)were not available in India till recently and relevant staff had insufficient training. The present study was performed to investigate the performance of M-IFA, IgM ELISA, and Weil–Felix test on 546 non-repeated serum samples from subjects suspected of having scrub typhus. One hundred and forty-three of these 546 samples were positive byM-IFA; these cases were alsoconfirmed clinically to have scrub typhus based on their dramatic responses todoxycycline therapy. IgMELISAwas positive in 122 of the 143M-IFApositive cases and the Weil–Felix test in 96. Though theWeil–Felix test is a heterophile agglutination test, it was found in this study to have good specificity but far too little sensitivity to use as a routine diagnostic test.IgMELISA can be a good substitute for M-IFA. Incorporation of multiple prototype antigens onM-IFA slides is likely one of the reasons for its superior performance. As newer and better diagnostic assays become available for scrub typhus diagnosis in developed countries, it will be imperative to also use such tests in other endemic countries to prevent over- or under-diagnosis of scrub typhus.

Item Type: Article
Uncontrolled Keywords: IgM ELISA; Microimmunofluorescence assay; Scrub typhus; Weil–Felix test
Subjects: Medicine > MMMC Manipal > Microbiology
Medicine > KMC Manipal > Medicine
Depositing User: KMC Manipal
Date Deposited: 08 Aug 2015 09:30
Last Modified: 08 Aug 2015 09:30
URI: http://eprints.manipal.edu/id/eprint/143790

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