Monitoring disease trends among travelers can inform both pretravel advice and posttravel management. Data from sentinel travelers upon their return to medically sophisticated environments can also benefit local populations in resource-limited countries.
Provider-based surveillance of travelers is increasingly sophisticated. Recently, networks such as GeoSentinel have provided cumulative trends in travel-related illness to assess pretravel risk for a mass gathering event--the Beijing Olympic Games. Data provided by the GeoSentinel also helped in determining the seasonality of dengue by region of travel and risk of acquiring schistosomiasis after a single short exposure. For chikungunya fever, detailed study of returned travelers exposed new clinical aspects of a disease previously studied in the tropics only. Clusters of hepatitis A, a vaccine-preventable disease, among European travelers, illustrated continued gaps in the preparation of the traveling public. Plasmodium knowlesi has emerged as the fifth human malaria parasite and is now a consideration in the diagnosis of febrile travelers from Asia. Automated global news scanning software is increasingly being able to detect and prioritize disease events.
Every year millions of travelers visit countries where they are exposed to pathogens that are usually rare in their home countries. Global surveillance of travel-related disease represents a powerful tool for the detection of infectious diseases. These data should encourage clinicians to take a detailed travel history during every patient encounter.