Leptospire

Leptospire is a term sometimes used to refer to a single organism of the genus Leptospira; in modern taxonomy, the genus name Leptospira is used to denote individual cells or strains. Leptospira are slender, spiral-shaped bacteria that cause leptospirosis. They are motile spirochetes with periplasmic flagella, enabling movement through viscous environments such as tissue and urine-contaminated water.

These bacteria inhabit a wide range of environments and are maintained in reservoir hosts including rodents, livestock, and dogs. Transmission to humans and other animals occurs through contact with urine or body fluids from infected animals, typically via skin abrasions or mucous membranes, often via contaminated water or soil. Infections can be mild or progress to severe disease.

Clinical presentation ranges from a mild febrile illness to a severe form known as Weil disease, which can involve jaundice, renal failure, and hemorrhagic manifestations. Diagnosis is based on clinical suspicion supported by laboratory testing, including serologic assays such as the microscopic agglutination test (MAT) and molecular methods like PCR; culture is slow and specialized. Treatment typically involves antibiotics such as doxycycline or penicillin, with early therapy reducing complications.

Prevention focuses on reducing exposure, using protective clothing for people in risk settings, rodent control, and vaccination of animals; human vaccines are limited to certain regions and contexts.