Beyond Fever-The Changing Face of Acute Leptospirosis: A Retrospective Observational Study from Western India

Leptospirosis is a zoonotic infection caused by pathogenic Leptospira species and remains a significant cause of acute febrile illness in tropical regions. Its clinical spectrum ranges from mild, self-limiting illness to severe multi-organ dysfunction. The disease is broadly classified into anicteric and icteric (Weil's disease) forms, the latter associated with jaundice and increased morbidity. In India, diagnosis is often challenging due to overlapping features with other endemic infections such as dengue and scrub typhus. Coinfections and changing epidemiological patterns, including increasing urban cases, further complicate clinical assessment. This study evaluated the demographic profile, clinical characteristics, organ involvement, coinfections, severity, management, and outcomes of adults hospitalized with acute leptospirosis, with comparison between icteric and anicteric phenotypes.

This retrospective observational study included 78 adults with laboratory-confirmed acute leptospirosis admitted over 30 months to a tertiary care hospital in Rajasthan, India. Diagnosis was established by positive Leptospira-specific immunoglobulin M (IgM) serology (>11 NTU) and/or polymerase chain reaction (PCR). Data regarding demographics, comorbidities, clinical features, organ involvement, coinfections, treatment, and outcomes were extracted from medical records. Organ involvement was defined using predefined clinical and laboratory criteria across major systems. Severe disease was defined as dysfunction of two or more organ systems. Icteric leptospirosis was defined by clinical jaundice and/or serum bilirubin ≥3 mg/dL. Coinfections were confirmed through appropriate laboratory testing. Continuous variables were expressed as median (interquartile range) and categorical variables as frequency (%). Subgroup comparisons were performed using the Mann-Whitney U test and Fisher's exact test.

The median age was 57 years (interquartile range 41-68), with slight male predominance (52.6%). Although 59% of patients were from rural areas, 41% were urban residents. Hypertension (25.6%) and diabetes mellitus (29.5%) were common comorbidities, while 42.3% had no prior illnesses. Anicteric disease predominated (84.6%), and 15.4% had icteric leptospirosis. Fever was present in 93.6% of patients. Hepatic (69.2%) and respiratory (66.7%) involvement were most frequent, and multi-organ dysfunction occurred in 61.5%. Coinfections were identified in 52.6% of cases, most commonly dengue (17.9%) and scrub typhus (14.1%). Coinfected patients were younger and had fewer comorbidities, with lower rates of renal, respiratory, and neurological involvement and reduced need for ventilatory support. Icteric patients were significantly younger (median 31.5 vs 58 years) and had longer hospital stays (10.5 vs 7 days). Hepatic involvement was universal in the icteric group, and secondary hemophagocytic lymphohistiocytosis (HLH) was markedly more frequent. Mortality was higher among icteric patients but did not reach statistical significance. Mechanical ventilation was required in 10.3% of patients. The median hospital stay was 7 days, and overall mortality was 2.6%, with both deaths occurring in patients with severe multi-organ dysfunction.

Acute leptospirosis exhibits diverse clinical presentations with frequent multi-organ involvement in hospitalized adults. Coinfections are common but did not consistently worsen outcomes. Icteric disease represents a more severe phenotype associated with greater complications and prolonged hospitalization. Early diagnosis and timely supportive management are critical to achieving favorable outcomes in endemic settings.