Clinical Profile and Predictors of Severity in Infantile Scrub Typhus - A Prospective observational study from a Tertiary Care Teaching Hospital in Southern India.

Background objectives: Scrub typhus (ST), a tropical infection caused by Orientia tsutsugamushi, has re-emerged as a global concern in the Asia-Pacific region. Limited data on ST in infants reveals unique presentations, complications, and severity predictors. This study was conducted to evaluate the occurrence of ST in infants, comparing clinical, laboratory and outcomes with ST in older children.

Methods: This is a prospective cohort study conducted in the Pediatrics department of a teaching hospital in South India. Children of < 12y years presenting with fever for > 5 days with serology confirmed ST using IgM ELISA for ST were included after excluding other common tropical infections.

Results: Out of 650 children, 60 (10%) were infants. Fever (100%) was the commonest presentation with mean duration of 9 days followed by cough and fast breathing. Eschar (33, 55%) was commonly seen in face (14, 23.3%) and were atypical (10, 16.6%) in appearance. Findings such as pallor, oedema, hepatosplenomegaly, lung crackles and hematological abnormalities like anemia, leukocytosis, elevated transaminases were more prevalent in infants compared to older children. Severe ST was observed in 34 (56.7%) infants, commonly presenting with pneumonia and shock. Doxycycline showed quicker defervesence with no adverse events in infants. Logistic regression identified hypoalbuminemia as a significant predictor of severe ST in infants.

Interpretation conclusion: ST in infants is common and pose diagnostic challenge due to overlapping features of other tropical infections. Timely therapy and risk stratification can improve the outcomes in resource limited setting.