Color enhanced Scanning Electron Micrograph (SEM) of Leptospira interrogans strain RGA. Two spirochetes bound to a 0.2 micrometer filter. Strain RGA was isolated in 1915 by Uhlenhuth and Fromme from the blood of a soldier in Belgium. Leptospira is known to cause the infectious disease leptospirosis, which attacks the liver and kidneys of humans and some animals. The disease can be transmitted via contact with infected water or urine. Leptospira is a genus of spirochaete bacteria, including a small number of pathogenic and saprophytic species. Leptospira was first observed in 1907 in kidney tissue slices of a leptospirosis victim who was described as having died of yellow fever. Magnification: unknown.