Expanding scrub typhus beyond territories with a varied presentation in the holy Himalayas (DPST–AIIMS Rishikesh study)

Abstract

Background: Scrub typhus, a rickettsial zoonosis, is endemic in Indian sub-continent, but is rare in holy Himalayan region due to natural adverse to both organism and vector. The study sought to describe the clinical profile of scrub typhus in the Himalayan region and adjoining plain lands. Methods and materials: We did a retrospective observational study of the positive cases from July 2018 to June 2019 in a tertiary care center. All possible risk factors, demographic details, clinical presentations, laboratory parameters, treatment, and outcomes were analyzed. Results: A total of 80 cases were analysed. Maximum cases were observed in month of September (post-monsoon). Major symptoms noted were fever, abdominal pain, headache, cough, breathlessness, and myalgia. Atypical presentations included were capillary syndrome and demyelinating polyneuropathy. Eschar detection rate was low. Among organ involvement, hematology system (70%) was most commonly observed followed by liver, kidney, brain, lungs, and heart respectively. Case fatality rate was 6.82%. Himalayan and non-Himalayan cohorts (n = 32 vs 48 respectively) did not show any statistically significant differences in clinical profile, although one could observe that Himalayan cohorts had higher incidences of leukopenia, splenomegaly, and myocarditis, while fever for >7days at admission, hepatomegaly, acute respiratory distress syndrome (ARDS) and requirement of mechanical ventilation, and major organ involvement and resulting admission in high definition unit and mortality were higher in the non-Himalayan cohorts. Uncontrolled diabetes, leucocytosis, liver and lung involvements were found to be predictor of hospital stay of >5days. Leucocytosis, kidney, liver, and brain involvements were found predictor for high dependency unit admission while development of shock was associated with liver, kidney, heart, and lung involvements. Similarly smoking >40 pack-years and presence of leucocytosis, kidney and brain involvements were significantly associated with mortality. Conclusion: The study reveals several atypical presentations and complications differing from the classical description, calling for redefining the clinical profile of scrub typhus. Himalayan cohorts have higher incidences of leukopenia, splenomegaly, and myocarditis compared to sub-Himalayan populations who have more incidence of ARDS. Brain and kidney involvements are found to have a higher incidence compared to other Indian scrub typhus cases. Ongoing study will answer more hidden truths of emerging scrub typhus.