Leptospirosis Leptospirosis is a bacterial disease that affects humans and animals. It is caused by bacteria of the genus Leptospira. Leptospirosis can cause a wide range of symptoms, including high fever, body ache, vomiting, jaundice, rash and renal failure. It can treated with antibiotics, such as doxycycline or penicillin, which should be given early in the course of the disease. Intravenous antibiotics may be required for persons with more severe symptoms.