Objective To explore the clinical characteristics, diagnosis and treatment of severe pulmonary hemorrhagic leptospirosis (PHL), and enhance the understanding of this disease.

Methods A comprehensive clinical analysis was conducted by combining one 45-year-old male with severe PHL admitted to the respiratory ICU and 49 cases of severe PHL published at home and abroad.

Results This patient was admitted to the emergency department due to fever, hemoptysis and breathing difficulties, with a history of exposure to epidemic water. Metagenomic next-generation sequencing (mNGS) was performed on bronchoalveolar lavage fluid (BALF) for diagnosis. After treatment with mechanical ventilation, glucocorticoids and penicillin, etc., the patient was cured and discharged. Comprehensive literature analysis: This disease is more common in males. Among the 50 cases, 42 cases (84.0%) were male, and 39 cases (78.0%) of the patients had a clear history of contact with epidemic water or rodents. The clinical manifestations were mostly fever, cough, hemoptysis, etc. The diagnosis mainly relied on the detection of serum leptospira antibodies, among which 10 cases were diagnosed by mNGS. All 50 patients were treated with antibiotics. Among them, 27 cases (54.0%) received glucocorticoid treatment, 40 cases (80.0%) received invasive mechanical ventilation, and 15 cases (30.0%) received extracorporeal membrane oxygenation (ECMO). This disease progressed rapidly, often complicated with multiple organ injuries, and had a relatively high mortality rate. In this group, 8 cases (16.0%) of patients died, among which 4 cases (8.0%) died within 72 hours of admission.

Conclusions The clinical manifestations of severe PHL are atypical, and it progresses rapidly with a high mortality rate. Early detection and early treatment can prevent the disease progression, and reduce the mortality rate. The mNGS technology is of great significance for the diagnosis of such diseases.