The Rising Tide of Scrub Typhus: Understanding Prevalence, Epidemiology and Outbreak Dynamics in Thiruvallur District

BACKGROUND: Scrub typhus, a vector-borne zoonotic disease caused by Orientia tsutsugamushi, poses a significant public health challenge in South and Southeast Asia. Despite its increasing incidence, data regarding its epidemiology and clinical patterns within specific Indian districts remain limited. OBJECTIVE: This study aimed to determine the prevalence, demographic distribution, seasonal trends, spatial clustering, occupational risk, and clinical features of scrub typhus among febrile patients in Thiruvallur district, Tamil Nadu, India. METHODS: A retrospective observational study was conducted analyzing medical records of 1,030 febrile patients tested from December 2022 to April 2025. Confirmed scrub typhus cases were identified via IgM ELISA. Data on demographics, clinical presentation, temporal distribution, and residential location were extracted and analyzed using descriptive statistics, time series plots, and spatial mapping. RESULTS: Scrub typhus prevalence was 12.62%, with near-equal gender distribution. Age-wise, cases peaked among 41–60 years. Seasonal analysis revealed marked post-monsoon incidence surges. Spatial mapping identified Poonamallee, Minjur, and Gummidipoondi blocks as hotspots. Occupational risk was highest among housewives (26.15%), agricultural workers (20.77%), and MGNREGS laborers (16.92%). Clinically, fever was universal, and eschar occurred in over 74% of cases, alongside systemic symptoms including headache, myalgia, and respiratory and gastrointestinal involvement. CONCLUSIONS: This study elucidates the epidemiological and clinical characteristics of scrub typhus in Thiruvallur district, emphasizing the influence of occupational, environmental, and seasonal factors. Findings support the need for targeted public health interventions, improved diagnostics, and enhanced clinical awareness to mitigate disease burden in endemic settings.