Serological Detection and Epidemiological Factors Associated with Scrub Typhus among Undifferentiated Febrile Illness Patients in a Tertiary Care Hospital

Scrub typhus is an arthropod-borne zoonotic bacterial infection caused by Orientia tsutsugamushi. It presents clinically as a non-specific febrile illness that need a high index of clinical suspicion for diagnosis. The mortality rate can be as high as 30% if not treated appropriately. Laboratory diagnosis is therefore important for confirming the cause of illness prior to initiating appropriate therapy. Hence we aimed to detect scrub typhus in serum samples of undifferentiated febrile illness patients and to correlate with the socioeconomic status of these individuals. We also aimed to study the seasonal variation associated with the disease. Serum samples from 143 febrile patients who were negative for other febrile illnesses were subjected to scrub typhus IgM ELISA. Scrub typhus IgM antibodies were found in 14 (9.8%) individuals of which 41-60 years being the most affected age group. Scrub typhus positivity was high during the months of October to December (P value 0.0056) with the individuals from the rural areas being the most affected (P value 0.027). To conclude, this study emphasises the importance of serological tests to detect scrub typhus and to include it as a differential diagnosis among undifferentiated febrile illnesses.