Clinical Manifestations and Risk Factors of Pediatric Leptospirosis: A Cross-Sectional Study at a Tertiary Care Center in Northern Vietnam

Background: Leptospirosis causes around 1 million cases and 60,000 deaths globally annually, predominantly affecting flood-prone tropical regions. Transmitted through contact with water or soil contaminated by animal urine infected with Leptospira spp., this bacterial zoonosis is classified as a high-risk Group B infectious disease in Vietnam. However, epidemiological and clinical data are scarce, particularly in pediatric populations. This study evaluated clinical and laboratory characteristics of leptospirosis cases at the National Children's Hospital, Hanoi, from January 2023 to August 2025. Methodology : All children admitted with probable or confirmed leptospirosis were enrolled. Clinical and laboratory data were analyzed to characterize disease manifestations and identify risk factors for severe leptospirosis. This was defined by the presence of organ dysfunction, including liver or renal failure, hemorrhage (particularly pulmonary), aseptic meningitis, cardiac arrhythmias, pulmonary insufficiency, or hemodynamic collapse. Principal Findings : Of 84 patients (37 confirmed, 47 probable), the mean age was 9.4 years, with 52.4% male and over half aged [≥] 10 years. Fever was the most common presenting symptom (85.7%); gastrointestinal and renal manifestations were frequent, including oliguria in 26.2% of cases. Key laboratory abnormalities included elevated D-dimer (81.8%), elevated C-reactive protein (75.6%), hypoalbuminemia (74.3%), increased liver enzymes (AST 63.3%, ALT 53.2%), and renal impairment ({approx} 46%). Severe disease developed in 48.8% of patients, most frequently as acute kidney injury. Hematuria was independently associated with increased severity (OR = 4.89). Conversely, fever, higher baseline albumin, and longer symptom duration prior to hospitalization were associated with a significantly reduced risk of severe disease. Conclusions : Pediatric leptospirosis in this cohort frequently presented with systemic inflammation and multi-organ involvement, particularly renal impairment. Nearly half the patients developed severe disease. Early recognition of renal signs, especially hematuria, and careful monitoring of albumin levels are critical to identifying children at risk for severe progression and optimizing clinical management.