Atypical Clinical Manifestations and Laboratory Predictors of Severe Scrub Typhus in Hospitalized Adults at Two Tertiary Care Hospitals in North India

INTRODUCTION: Scrub typhus is a re-emerging, neglected tropical disease in India, often presenting with nonspecific symptoms. While classical features are well-documented, atypical and severe manifestations are underreported and frequently misdiagnosed. OBJECTIVES: Our objective was to describe uncommon clinical manifestations of scrub typhus in hospitalized patients at two tertiary care hospitals in Northern India. METHODS: This prospective cross-sectional study included 22 adult patients (no controls) with serologically confirmed scrub typhus (IgM ELISA positive) presenting between January 2024 and June 2025. Only cases with atypical manifestations were included. Demographic, clinical, laboratory, and imaging data were analysed descriptively. RESULTS: The study of 22 hospitalized scrub typhus cases with atypical presentations revealed the presence of multi-organ involvement with marked hepatic and renal impairment. In severe cases, mean values of urea (97.7 vs. 10.2 mg/dL, p = 0.001), creatinine (2.14 vs. 0.84 mg/dL, p = 0.004), ALT (218.7 vs. 11.5 IU/L, p = 0.011), AST (208.5 vs. 37.2 IU/L, p = 0.008), and ALP (427.6 vs. 95.6 IU/L, p = 0.001) were markedly elevated. ROC analysis of urea (AUC = 0.902), creatinine (AUC = 0.888), and ALP (AUC = 0.875) confirmed them as strong predictors of severe disease. CONCLUSION: The correlation heatmap and boxplots highlighted strong associations between ALT and AST (r = 0.98) as well as urea and creatinine (r = 0.83), along with distinguishing outliers indicating associated hepatic injury, renal impairment, and thrombocytopenia.