The infectious disease caused by ingesting drinking water or food contaminated with the bacterium Salmonella typhi is called thyphoid fever. It is common in areas of poor sanitation, where sewage may mix with drinking water, or flies may carry the bacteria from feces to food. A similar disease, called paratyphoid fever, is caused by a related bacterium.
The typhoid bacilli incubate for one to three weeks in the carrier and pass from the stomach and intestines to the bloodstream, traveling to the spleen, liver, and gallbladder. Once infected with the bacteria, a person may carry them in the gallbladder for years and excrete them in the feces.
Typhoid epidemics are common in developing countries, but fewer than 600 cases occur annually in the United States. Improved santitation and immunization programs can prevent the spread of the disease. Infected individuals should be isolated until the disease passes.
Typhoid fever is diagnosed by growing a culture of typhoid bacteria from samples of blood, feces, or urine, or by testing the blood for typhoid antibodies. The early symptoms are fever, headache, weakness, appetite loss, a tender abdomen, constipation, and confusion. As the illness progresses, red spots appear on the chest and belly, and the spleen and liver enlarge. The illness usually lasts about four weeks with treatment of chloramphenicol and antibiotics. If left untreated, severe complications (intestinal bleeding, urinary tract infection, renal failure, or peritonitis) may occur. Infection bestows lifelong immunity.
Immunization against typhoid fever is recommended for travel outside the United States, Canada, Northern Europe, Australia, and New Zealand. The typhoid vaccine is given as two shots and requires a booster shot after two to three years.