Leptospirosis is caused by Leptospira bacteria. It is most commonly transmitted through direct contact with urine, blood, or tissue of an infected animal. Direct contact commonly occurs when broken skin, open wounds, or the lining of the eyes, nose, sinuses, and mouth come in contact with infected material; in ordinary circumstances, this usually happens through contact with infected water (e.g. wading in floodwater) or soil. This also means that infection can occur even if a person has no cuts or wounds, contrary to popular belief. Person-to-person transmission is possible, but rare. The bacteria can incubate for as long as 28 days, which means symptoms can take as long as one month after contact with infected material or environment to manifest.