The bacterium that causes typhoid fever, Salmonella typhi, spreads through food, water or contaminated drinks. If you eat or drink something that is contaminated, the bacteria enter the body. They travel to the intestine and then to the bloodstream. In the blood, they travel to the lymph nodes, gallbladder, liver, spleen and other parts of the body.
Some people may become carriers of Salmonella typhi bacteria and continue to expel bacteria in their faeces for years, spreading the disease.
Typhoid fever is common in developing countries, but less than 400 cases are reported in the United States each year. Most cases in the United States come from other countries where typhoid fever is common.