Epidemiology of Post-Travel Illnesses

International travel is becoming increasingly popular. Information on epidemiology of specific post-travel illnesses provides guidance for pretravel intervention strategies as well as differential diagnoses in ill returned travelers. Lack of surveillance data for imported infectious diseases prompted the establishment of large-scale travel-related sentinel surveillance networks. Various approaches to risk characterization in travel medicine research provide a wide spectrum of data, but also have considerable limitations. The chapter summarizes results of available systematic studies investigating the epidemiology of post-travel illness in ill returned in- and outpatients, including data on these large-scale surveillance systems. In addition, available methods and limitations of post-travel research are discussed.