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Published on: November 4, 2025
Serodiagnosis of Scrub Typhus at a Tertiary Care Hospital from Southern India
K S Roopa1, K Karthika2, Madhan Sugumar3
1PhD scholar, Department of Microbiology, Jawaharlal Institute of Post Graduate Medical Education and Research , Puducherry, India .
Introduction:
Scrub typhus, a zoonotic disease is one of the most covert emerging and re-emerging Rickettsial infections. There is an upsurge in the incidence of the disease worldwide with ever-changing habitat. Clinical diagnosis of scrub typhus is challenging as the signs and symptoms of scrub typhus are similar to other febrile illnesses. In developing countries, among the various laboratory tests to diagnose scrub typhus, Weil-Felix test is commonly performed despite its low sensitivity. The Immunofluorescence antibody (IFA) test has its limitations in terms of cost and expertise required. The present study was conducted to determine the seropositivity of IgM ELISA for scrub typhus in clinically suspected cases.
Materials And Methods:
Weil-Felix test and IgM ELISA were performed using clinically suspected cases of scrub typhus using commercially available kits.
Results:
Out of 482 samples tested, 109 were positive by both Weil-Felix test and IgM ELISA. One hundred and sixteen samples which were negative by Weil-Felix test reacted positive by IgM ELISA. Fourteen samples which were positive by Weil-Felix test were negative by ELISA.
Conclusion:
Owing to the limitations of the Weil-Felix test and IFA, commercially available recombinant IgM ELISA which has a good sensitivity and specificity may be an alternative in laboratories with moderate set up.
Insights
Scrub typhus diagnosis is challenging due to overlapping symptoms with other febrile illnesses. IgM ELISA shows higher sensitivity than the Weil-Felix test for detecting scrub typhus in suspected cases.
Area of Science:
- Medical Microbiology
- Infectious Diseases
- Epidemiology
Background:
- Scrub typhus is an emerging and re-emerging zoonotic Rickettsial infection with increasing global incidence.
- Clinical diagnosis is difficult due to non-specific febrile symptoms.
- Traditional diagnostic methods like Weil-Felix test have low sensitivity, and Immunofluorescence antibody (IFA) test requires specialized expertise and is costly.
Purpose of the Study:
- To evaluate the seropositivity of IgM ELISA for scrub typhus diagnosis in clinically suspected individuals.
- To compare the diagnostic performance of IgM ELISA against the Weil-Felix test.
Main Methods:
- Clinically suspected scrub typhus cases were tested using commercially available kits for both Weil-Felix test and IgM ELISA.
- A total of 482 samples were analyzed.
Main Results:
- Out of 482 samples, 109 were positive by both Weil-Felix and IgM ELISA.
- IgM ELISA identified an additional 116 samples as positive that were negative by Weil-Felix test.
- 14 samples positive by Weil-Felix test were negative by IgM ELISA.
Conclusions:
- Commercially available IgM ELISA demonstrates good sensitivity and specificity for scrub typhus diagnosis.
- IgM ELISA can serve as a viable alternative diagnostic tool in laboratories with moderate infrastructure, overcoming limitations of Weil-Felix and IFA tests.
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