Coloured scanning electron micrograph (SEM) of Leptospira interrogans spirochete (LAI) bacteria. This spiral or helical shaped prokaryote is an obligate aerobe that is highly motile. It causes the disease leptospirosis, the most widespread bacterial infection in the world, affecting both animals and humans. It is a bacterial infection passed from animals to humans by way of contaminated urine. Leptospirosis is also know as canicola fever, haemorrhagic jaundice, infectious jaundice, mud fever, spirochaetal jaundice, swamp fever, swineherd's disease and caver's flu. The rare acute form of human infection that can lead to death is known as Weil's Disease. Magnification: x3,000 when shortest axis printed at 25 millimetres.