This study will evaluate a new (conjugate) vaccine for typhoid fever, which remains a serious disease especially difficult to treat in developing countries. Salmonella typhi, the bacteria causing typhoid fever, have become resistant to several antibiotics increasing the difficulty of treating the disease. The disease may have serious complications effecting bones, brain, and intestines, with permanent injury or death. Methods to control typhoid fever, such as a sanitary water and food supply, along with effective sewage treatment, are not likely to be available soon in those countries.