Typhoid fever is an acute, life-threatening febrile illness caused by the bacterium Salmonella enterica Typhi. An estimated 16 million cases of typhoid fever and 600,000 related deaths occur worldwide each year. Approximately 2.6 cases of typhoid fever were reported to the Centers for Disease Control and Prevention per 1 million U.S. citizens and residents traveling abroad during the period 1992–1994.