Leptospirosis is an acute febrile systemic disease caused by infection with Leptospira bacteria. Leptospirosis is caused by epidemic or sporadic occurrence. Pandemics are closely related to climatic conditions such as torrential rains and floods (August to November in our country). Sporadic occurrence occurs at any time of the year when residents living in indigenous areas are exposed to contaminated environments during outdoor activities. Leptospirosis is classified as the third-class infectious disease of legal infectious diseases in Korea. It is also called wale seed disease, harvest salt, and paddy farmer's disease. It can be infected by humans and animals (a common factor epidemic), and it is transmitted to humans by infecting rodents, especially rats. In our country, it is known to occur frequently to farmers, soldiers, and volunteers who are engaged in crop damage prevention or disaster recovery work when torrential rains or floods occur during the harvest season.