Leptospira is a genus of spirochaete

Spirochaete

Spirochaetes belong to a phylum of distinctive Gram-negative bacteria, which have long, helically coiled cells...

 bacteria, including a small number of pathogenic and saprophytic species. Leptospira was first observed in 1907 in kidney

Kidney

The kidneys, organs with several functions, serve essential regulatory roles in most animals, including vertebrates and some invertebrates. They are essential in the urinary system and also serve homeostatic functions such as the regulation of electrolytes, maintenance of acid–base balance, and...

 tissue slices of a leptospirosis

Leptospirosis

Leptospirosis is caused by infection with bacteria of the genus Leptospira, and affects humans as well as other mammals, birds, amphibians, and reptiles.The...

 victim who was described as having died of "yellow fever

Yellow fever

Yellow fever is an acute viral hemorrhagic disease. The virus is a 40 to 50 nm enveloped RNA virus with positive sense of the Flaviviridae family....

."
Leptospira, together with the genera Leptonema

Leptonema

Leptonema is a genus of flowering plant belonging to the family Phyllanthaceae....

 and Turneria

Turneria

Turneria is a genus of ants that belongs to the ant subfamily Dolichoderinae. They form small colonies of fewer than 500 workers, and nest in trees and twigs....

, is a member of the family Leptospiraceae

Leptospiraceae

Leptospiraceae is a family of spirochetes.It includes the genus Leptospira....

. The genus Leptospira is divided into 20 species based on DNA hybridization studies.

Pathogenic Leptospira

Leptospira interrogans

Leptospira kirschneri

Leptospira noguchii

Leptospira alexanderi

Leptospira weilii

Leptospira genomospecies 1

Leptospira borgpetersenii

Leptospira santarosai

Leptospira kmetyi

Intermediates or opportunistic Leptospira

Leptospira inadai

Leptospira fainei

Leptospira broomii

Leptospira licerasiae

Leptospira wolffii

Non-pathogenic Leptospira

Leptospira biflexa

Leptospira meyeri

Leptospira wolbachii

Leptospira genomospecies 3

Leptospira genomospecies 4

Leptospira genomospecies 5

Members of Leptospira are also grouped into serovars according to their antigenic relatedness.