Human leptospirosis is a zoonotic disease caused by bacteria of the genus Leptospira. Due to its frequent inapparent course or mild severity with unspecific symptoms and limited availability of diagnostic laboratories the incidence of leptospirosis is likely to be underestimated. The hospital of Val Müstair is the major healthcare provider of a rural mountain valley in the canton of Graubünden/ Switzerland with approximately 1500 inhabitants. A relevant prevalence of Leptospira spp. antibodies in the population of the Val Müstair due to its geographic and social risk profile for Leptospira infection, namely the close contact of the population to both livestock and wildlife in agriculture and hunting is estimated. The aim of this study is to analyze the burden of this disease in order to evaluate the need of preventive measures. In addition, seroepidemiological data for the Hepatitis E virus (HEV) and for tularemia will be collected.