Leptospirosis (also known as Weil's disease, canicola fever, canefield fever, nanukayami fever or seven day fever) is a bacterial disease. It is caused by spirochaetes of the genus Leptospira. This bacterium affects humans and many animals, including mammals, birds, amphibians, and reptiles. It was first described by Adolf Weil in 1886. At the time he reported an "acute infectious disease with enlargement of spleen, jaundice and nephritis". The pathogen, Leptospira-genus bacteria was isolated in 1907 from a post mortem kidney slice.
Leptospirosis is a relatively rare bacterial infection in humans. The infection is commonly transmitted to humans by allowing fresh water that has been contaminated by animal urine (often from rats) to come in contact with the skin, eyes or with the mucous membranes.
It usually causes heart failure, kidney failure or liver failure, and most sufferers die if they are not treated urgently. The disease causes little concern, as it is quite rare
Except for tropical areas, Leptospirosis seems to occur most often in the months August to September, in the Northern Hemisphere.