In 2012, the number of international tourist arrivals worldwide was projected to reach a new high of 1 billion arrivals, a 48% increase from 674 million arrivals in 2000. International travel also is increasing among U.S. residents. In 2009, U.S. residents made approximately 61 million trips outside the country, a 5% increase from 1999. Travel-related morbidity can occur during or after travel. Worldwide, 8% of travelers from industrialized to developing countries report becoming ill enough to seek health care during or after travel. Travelers have contributed to the global spread of infectious diseases, including novel and emerging pathogens. Therefore, surveillance of travel-related morbidity is an essential component of global public health surveillance and will be of greater importance as international travel increases worldwide.