Severe Leptospirosis With Diffuse Alveolar Hemorrhage Following Contact With a Sick Dog: A Case Report

Leptospirosis is a zoonotic infection with a broad spectrum of clinical manifestations, ranging from mild self-limiting illness to Weil's disease, its classic severe form.Humans can become infected through exposure to contaminated water or the urine of infected animals, including dogs.Diffuse alveolar hemorrhage is a rare but life-threatening manifestation that may initially present with hemoptysis.A 29-year-old man presented with fever, hemoptysis, anorexia, and asthenia, progressing to acute respiratory distress and jaundice.Two weeks before symptom onset, he had cared for an abandoned dog with a clinical presentation compatible with leptospirosis according to veterinary assessment.The patient's laboratory evaluation revealed anemia, severe thrombocytopenia, acute kidney injury, markedly elevated creatine kinase levels, and increased total and direct bilirubin.Chest CT demonstrated bilateral ground-glass opacities and consolidations.Weil's disease with diffuse alveolar hemorrhage was suspected, and leptospirosis was subsequently confirmed.Hematologic and renal dysfunction improved with conservative management, but progressive respiratory failure required invasive mechanical ventilation for five days.The patient completed a seven-day course of antibiotic therapy with progressive clinical and laboratory improvement.Regarding the dog, veterinary clinicians suspected leptospirosis; however, it died before confirmatory testing.This case underscores the importance of obtaining a thorough animal exposure history in patients presenting with hemoptysis, as early suspicion of leptospirosis is essential for prompt diagnosis and treatment.