The Typhoid-fever is a life-threatening illness caused by the bacterium Salmonella typhi. This disease is mainly founded among the developing nations. According to a survey, about 12.5 million people are affected every year just because of the Typhoid-fever. The Salmonella typhi lives among the humans only. Persons with typhoid fever carry the bacteria in the bloodstream and intestinal tract. In addition, a small number of persons, called carriers, recover from typhoid fever but continue to carry the bacteria. Both ill persons and carriers shed Salmonella typhi in their stools.