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 (≈ 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.

AUTHOR SUMMARY

Leptospirosis is a neglected infectious disease that poses a significant global burden, particularly in tropical countries. Infection spreads from animals to humans via contact with water or soil contaminated by animal urine. While it causes severe illness or even death, information on how it impacts children in Vietnam remains extremely limited.

To fill this gap, this study tracked 84 children treated for leptospirosis in Hanoi between 2023 and 2025. The results revealed that the vast majority experienced a fever alongside damage to multiple organs, especially the kidneys. Nearly half the patients experienced severe illness, with acute renal failure being the most common complication. The presence of red blood cells in the urine was a major warning sign for severe disease progression. Conversely, higher blood albumin levels, fever, and longer illness before hospitalization were each linked to a lower risk of a severe outcome.

Leptospirosis is often misdiagnosed as it has symptoms in common with other tropical fevers. These findings underscore the importance of simple laboratory tests to check for signs of kidney damage and to monitor blood proteins to identify vulnerable children early, thereby enabling timely treatment and thus improving their chances of making a full recovery.