# Leptospirosis in Central Romania: A 17-Year Single-Center Cohort Study of Hospitalized Adults

## TL;DR

This study analyzed 17 years of hospitalized leptospirosis cases in central Romania, finding a male predominance, late-summer peak, and significant severe disease burden.

## Contribution

The study provides a long-term, single-center analysis of leptospirosis epidemiology and severity in a temperate region.

## Key findings

- Hospitalized leptospirosis showed a marked male predominance and a peak in August–September.
- Severe disease occurred in 40.6% of cases and was more frequent in men and pre-pandemic years.
- Severe cases were associated with renal and liver symptoms, lab abnormalities, and longer hospital stays.

## Abstract

Leptospirosis is an important zoonosis that can present as a self-limited influenza-like illness or progress to severe, including life-threatening multiorgan dysfunction. We report the epidemiology, clinical profile, and correlates of severity among adults hospitalized patients with leptospirosis diagnosed in central Romania over a period of 17 years. We conducted a retrospective, single-center cohort study of adults admitted between 1 January 2008 and 1 December 2025 with laboratory-confirmed leptospirosis. Confirmation was based on positive anti-Leptospira IgM serology, with repeat testing when the initial result was equivocal and confirmation with a microscopic agglutination test. We extracted demographic, exposure, clinical, laboratory, treatment, and outcome data from medical records. The modified Faine score was also calculated using admission data. Sixty-four patients were included in this analysis, of which 53 (82.8%) were male patients. Admissions peaked in 2023–2025 (34/64, 53.1%) and in the August–September months. Reported exposures were predominantly peri-domestic (46.9%), followed by rural/animal-related occupations (20.3%) and freshwater contact (17.2%). Severe disease occurred in 26/64 (40.6%), was more frequent in men (p = 0.021), and was more common pre-pandemic than during/after the pandemic (p < 0.001). Severe cases were associated with oliguria/anuria, hematuria, and jaundice, alongside higher urea/creatinine and bilirubin, lower hemoglobin and lymphocyte percentages, and a longer hospitalization period. One in-hospital death occurred (1.6%). Serogroup identification was available for 10 patients (15.6%) (pre-pandemic only). The mean modified Faine score was 27.5 ± 6.0. In this temperate-region cohort study, hospitalized leptospirosis showed a marked male predominance, a late-summer peak, and a substantial burden of severe disease. Early renal and hepatobiliary manifestations with concordant laboratory abnormalities may support timely risk stratification and escalation of care, while expanded molecular diagnostics and systematic typing are needed to clarify temporal trends and guide prevention.