Background: Scrub typhus is a rickettsial infection which is caused by Orientia tsutsugamushi and transmitted by the bite of chigger. It is an important cause of acute undifferentiated febrile illness. Delay in diagnosis may prove to be life threatening.
Objective: The aim of this study was to determine the diagnostic accuracy and clinical usefulness of polymerase chain reaction (PCR) for the diagnosis of scrub typhus through a comparison of PCR and IgM Micro-IFA with IgM ELISA positive cases.
Material and Methods: All cases clinically suspected of scrub typhus over a period of 1 year were analysed. EDTA blood and sera were collected for PCR and serologic evaluation by IgM ELISA and IgM Micro- IFA respectively. Results: Out of 327 clinically suspected cases of scrub typhus, 177 cases were positive by IgM ELISA which were further subjected to IgM Micro- IFA and PCR. Out of 177 IgM ELISA positive cases, 174(98.3%) cases were positive for IgM IFA and 17(9.6%) cases were positive by PCR. The results of PCR showed a sensitivity and specificity of 9.6% and 100% respectively. Conclusion: Due to uncommon presentation of rash, lymphadenopathy, eschar heavy reliance on these features to clinically diagnose scrub typhus should be discouraged. PCR showed high specificity but low sensitivity as most patients had received antibiotics. Late presentation in most cases decreased chances of isolating DNA from the blood.
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