微生物および生化学技術ジャーナル

概要

Scrub Typhus and Leptospirosis: The fallacy of Diagnosing with IgM Enzyme Linked Immunosorbant Assay

Nitin Gupta, Rama Chaudhry, Bijay Mirdha, Bimal Das, Lalit Dar, Sushil Kabra, Rakesh Lodha, Aparajit Dey, Rita Sood, Naveet Wig and Vishnubhatla Sreenivas

Introduction: Leptospirosis and scrub typhus are important causes of acute febrile illness in India. IgM Enzyme Linked Immunosorbant Assay (ELISA) is the most common diagnostic modality used for their diagnosis. The common epidemiology of both the diseases creates an opportunity of dual infections with these diseases. Therefore, the objective of the study was to detect and evaluate the cases of serological and molecular dual infections.

Methodology: A cross-sectional diagnostic study from October 2013 to October 2015 was conducted on 258 patients with acute febrile illness. All the samples were subjected to IgM ELISA for scrub typhus and leptospirosis. The samples that were positive for both scrub typhus and leptospirosis were subjected to serological tests for other infections. They were also subjected to PCR assays to find out the cases of molecular dual infections.

Results: A total of twenty serum samples were positive by IgM ELISA for leptospirosis while thirty five serum samples were positive by IgM ELISA for scrub typhus. Among these, ten samples were positive for both the serological tests. These dual positives were additionally positive by serology for some other infections [Dengue (n = 2), Mycoplasma pneumoniae (n = 1), Malaria (n = 1), Chlamydia pneumoniae (n = 6), Typhoid (n = 2) and Legionella pneumophila (n = 1)]. Only one case of molecular dual infection was confirmed.

Conclusion: The possibility of serological co-infections should be investigated in endemic areas. In a case of serological dual infection, since there are high chances of serological cross reactivity, molecular confirmation should be sought for. The choice of therapy in inconclusive cases should include those drugs that cover for both the infections.