钩端螺旋体病（英语：Leptospirosis，又译细螺旋体症）简称钩体病，是一种人畜共通传染病，由钩端螺旋体类细菌引起的感染。患者可能无症状或表现轻度头痛、肌肉疼痛、发热到严重的肺出血或脑膜炎。如果此感染造成黄疸、肾衰竭或出血，此时疾病又称为威尔氏病（英语：Weil's disease）。如果造成肺部大量出血则称作严重肺出血症候群。钩端螺旋体病在1886年的德国由威尔氏发现。

Leptospirosis is an infection caused by corkscrew-shaped bacteria called Leptospira. Signs and symptoms can range from none to mild such as headaches, muscle pains, and fevers; to severe with bleeding from the lungs or meningitis. If the infection causes the person to turn yellow, have kidney failure and bleeding, it is then known as Weil's disease. If it causes lots of bleeding from the lungs it is known as severe pulmonary haemorrhage syndrome.