Gr. leptos = slender, and speira = coil.

Genus of bacteria consisting of single, finely coiled,motile, aerobic cells. In 1886, German physician Adolf Weil described a clinical syndrome characterized by splenomegaly, jaundice, and nephritis, although the disease was likely recognized in ancient China as an occupationalhazard of rice farming. The organism was first describedin 1907 by Arthur Stimson, who observed spirochetes with curved ends in the kidneys of a patient thought to have died of yellow fever. He named it Spirochaeta interrogansbecause it looked like a question mark.

The cause of Weil’s disease was isolated independently in 1915 in Japan and Germany. In Japan, Inada et al. detected spirochetes, which they named Spirochaeta icterohaemorrhagiae, in the blood of coal miners with infectious jaundice. In Germany, 2 groups of physicians (Uhlenhuth etal. and Hubener et al.) studied soldiers afflicted with “Frenchdisease” in the trenches of northeastern France. The Germans were arguing over priority, however, and overlooked the publications by Inada’s group, which predated their own by 8 months. The genus Leptospira was suggested in 1917 byHideyo Noguchi “on account of its fine and minute windings.”