Infant Scrub Typhus: A 10-Year Experience from a Tertiary Center in South India (The ScrubIn Study)

Scrub typhus is a potentially fatal and neglected tropical infectious disease caused by the bacterium Orientia tsutsugamushi; limited information is available on scrub typhus in infants. In the present retrospective study, the clinical presentation, laboratory findings, and outcomes of infants with scrub typhus admitted to a tertiary care hospital in India were investigated over a decade. A retrospective review of 49 infants (<1 year) with laboratory-confirmed scrub typhus admitted between 2014 and 2023 was conducted. Clinical, laboratory, and outcome data were analyzed to identify predictors of severe disease. A total of 49 infants, with a mean age of 5 months, were diagnosed with scrub typhus. Most cases clustered between October and January, indicating seasonality of the infection. Despite their limited indoor exposure, nearly half of the infants had an identifiable eschar, predominantly on the head or neck and in the inguinal region. Severe disease, defined by organ dysfunction (acute respiratory distress syndrome, shock, myocarditis, encephalitis, renal failure, or hepatic failure), was observed in 24 (49.0%) infants, all of whom required pediatric intensive care unit care. Elevated leukocyte count, severe thrombocytopenia, and elevated hepatic transaminases predicted severity, whereas the presence of an eschar was protective. The overall mortality was 10.2%, which was considerably higher than the 1% to 3% reported in broader pediatric cohorts, underscoring infants as a uniquely vulnerable group. This was one of the largest infant scrub typhus cohorts, highlighting distinctive epidemiological and clinical features, possible transmission pathways, susceptibility, outcomes, and early markers of severity, underscoring the need for heightened clinical suspicion and timely doxycycline therapy in endemic regions.