Scrub Typhus in the Modern Era: Clinical Spectrum, Organ Involvement, and Outcomes in a South Indian Tertiary Care Setting

Background Scrub typhus, an acute febrile illness caused by Orientia tsutsugamushi, is re-emerging in India, with varied clinical presentations and potentially life-threatening complications. However, data from southern India remain limited. Aim This study aimed to describe the clinical characteristics and outcomes of patients diagnosed with scrub typhus based on positive IgM antibody results detected by enzyme-linked immunosorbent assay (ELISA). Methods We conducted a prospective hospital-based observational study at a tertiary care center in Bengaluru from September 2022 to February 2024. Fifty adult patients with IgM ELISA-confirmed scrub typhus were enrolled. Demographic details, clinical features, laboratory parameters, complications, and outcomes were systematically recorded and analyzed. Results The mean age of patients was 50.5 ± 13.2 years, with equal male-to-female distribution (25 (50%) males and 25 (50%) females). Fever was present in 50 (100%) patients, followed by myalgia in 33 (66%) and gastrointestinal symptoms in 25 (50%) patients; eschar was detected in 12 (24%) patients. Laboratory abnormalities included elevated transaminases (AST > 3× upper limit of normal) in 15 (30%) patients, thrombocytopenia (<100 × 10³/μL) in 11 (22%) patients, and raised CRP (>5 mg/dL) in 48 (96%) patients. Major complications included acute respiratory distress syndrome (11, 22%), pneumonia (10, 20%), myocarditis (8, 16%), and acute kidney injury (6, 12%). Intensive care unit (ICU) admission was required in 39 (78%) patients, with ventilatory support required in 12 (24%) patients. All patients survived with appropriate treatment. Conclusion Scrub typhus presents with nonspecific clinical features and significant morbidity due to multi-organ involvement; however, favorable outcomes can be achieved with early recognition and timely treatment. Our findings emphasize the need for heightened clinical suspicion and routine testing for scrub typhus in patients with acute undifferentiated febrile illness in endemic regions.