Typhoid is caused by the bacterium Salmonella Typhi (S. Typhi). It spreads primarily through contaminated food, water, or drink that has been contaminated by the feces or urine of an infected person. The bacteria enter the body through consumption of these contaminated sources, travel into the intestines, and then into the bloodstream, affecting various organs. Poor sanitation, lack of clean water, and improper hygiene are major contributors to the spread of typhoid. It is a human-only infection, with no animal reservoirs, and can also be spread by asymptomatic carriers who continue to shed the bacteria.