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Diagnostic performance of serological tests to detect antibodies against acute scrub typhus infection in central India.
Indian J Med Microbiol. 2018 Jan-Mar; 36(1):108-112.IJ

Abstract

Background

Differentiating scrub typhus from other acute febrile illness is difficult due to non specificity of clinical symptoms and relative absence of eschar in Indian population. The diagnosis thus relies mainly on laboratory tests. Antibody based serological tests are mainstay of scrub typhus diagnosis. Here, we evaluated the diagnostic performance of IgM ELISA, IgM IFA and ICT to detect antibodies against O. tsutsugamushi in acute serum of febrile patients.

Methodology

The serum samples from 600 randomly selected patients suffering from acute undifferentiated fever were tested by all the three tests mentioned above. We used latent class analysis to generate unbiased results as all the tests for scrub typhus diagnosis are imperfect and none of them can be considered as reference standard.

Results

We found that IgM ELISA with cutoff titer 0.5 OD has high diagnostic accuracy (sensitivity 99.9% and specificity 99.15) than IgM IFA (sensitivity 96.8% and specificity 99.7%) for scrub typhus diagnosis. ICT used in our study had very high specificity 100% but low sensitivity (38%) which would limit its use for acute serum samples. ICT being a screening or point of care test, has to be more sensitive while some compromise with specificity is affordable. Hence, optimal cutoff for ICT should be evaluated under different settings.

Conclusion

IgM ELISA being simple and affordable could be an alternative diagnostic test to IgM IFA which is subjective and costly.

Authors+Show Affiliations

Department of Microbiology, Mahatma Gandhi Institute of Medical Sciences, Sewagram, Wardha, India.Department of Microbiology, Mahatma Gandhi Institute of Medical Sciences, Sewagram, Wardha, India.Department of Community Medicine, Mahatma Gandhi Institute of Medical Sciences, Sewagram, Wardha, India.

Pub Type(s)

Evaluation Study
Journal Article

Language

eng

PubMed ID

29735837

Citation

Pote, Kiran, et al. "Diagnostic Performance of Serological Tests to Detect Antibodies Against Acute Scrub Typhus Infection in Central India." Indian Journal of Medical Microbiology, vol. 36, no. 1, 2018, pp. 108-112.
Pote K, Narang R, Deshmukh P. Diagnostic performance of serological tests to detect antibodies against acute scrub typhus infection in central India. Indian J Med Microbiol. 2018;36(1):108-112.
Pote, K., Narang, R., & Deshmukh, P. (2018). Diagnostic performance of serological tests to detect antibodies against acute scrub typhus infection in central India. Indian Journal of Medical Microbiology, 36(1), 108-112. https://doi.org/10.4103/ijmm.IJMM_17_405
Pote K, Narang R, Deshmukh P. Diagnostic Performance of Serological Tests to Detect Antibodies Against Acute Scrub Typhus Infection in Central India. Indian J Med Microbiol. 2018 Jan-Mar;36(1):108-112. PubMed PMID: 29735837.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Diagnostic performance of serological tests to detect antibodies against acute scrub typhus infection in central India. AU - Pote,Kiran, AU - Narang,Rahul, AU - Deshmukh,Pradeep, PY - 2018/5/9/entrez PY - 2018/5/8/pubmed PY - 2018/9/28/medline KW - Immunoglobulin M enzyme-linked immunosorbent assay KW - immunochromatographic test KW - indirect immunofluorescence assay KW - latent class analysis KW - scrub typhus KW - serology SP - 108 EP - 112 JF - Indian journal of medical microbiology JO - Indian J Med Microbiol VL - 36 IS - 1 N2 - Background: Differentiating scrub typhus from other acute febrile illness is difficult due to non specificity of clinical symptoms and relative absence of eschar in Indian population. The diagnosis thus relies mainly on laboratory tests. Antibody based serological tests are mainstay of scrub typhus diagnosis. Here, we evaluated the diagnostic performance of IgM ELISA, IgM IFA and ICT to detect antibodies against O. tsutsugamushi in acute serum of febrile patients. Methodology: The serum samples from 600 randomly selected patients suffering from acute undifferentiated fever were tested by all the three tests mentioned above. We used latent class analysis to generate unbiased results as all the tests for scrub typhus diagnosis are imperfect and none of them can be considered as reference standard. Results: We found that IgM ELISA with cutoff titer 0.5 OD has high diagnostic accuracy (sensitivity 99.9% and specificity 99.15) than IgM IFA (sensitivity 96.8% and specificity 99.7%) for scrub typhus diagnosis. ICT used in our study had very high specificity 100% but low sensitivity (38%) which would limit its use for acute serum samples. ICT being a screening or point of care test, has to be more sensitive while some compromise with specificity is affordable. Hence, optimal cutoff for ICT should be evaluated under different settings. Conclusion: IgM ELISA being simple and affordable could be an alternative diagnostic test to IgM IFA which is subjective and costly. SN - 1998-3646 UR - https://www.unboundmedicine.com/medline/citation/29735837/Diagnostic_performance_of_serological_tests_to_detect_antibodies_against_acute_scrub_typhus_infection_in_central_India_ L2 - https://linkinghub.elsevier.com/retrieve/pii/IndianJMedMicrobiol_2018_36_1_108_231673 DB - PRIME DP - Unbound Medicine ER -