Typhoid fever is an acute illness associated with fever
caused by the Salmonella typhi bacteria. It can also be caused by
Salmonella paratyphi, a related bacterium that usually causes a less
severe illness. The bacteria are deposited in water or food by a human
carrier and are then spread to other people in the area.
incidence of typhoid fever in the United States has markedly decreased
since the early 1900s, when tens of thousands of cases were reported in
the U.S. Today, less than 400 cases are reported annually in the United
States, mostly in people who have recently traveled to Mexico and South
America. This improvement is the result of better environmental
sanitation. India, Pakistan, and Egypt are also known as high-risk areas
for developing this disease. Worldwide, typhoid fever affects more than
21 million people annually, with about 200,000 people dying from the
How Do People Get Typhoid Fever?
Typhoid fever is
contracted by drinking or eating the bacteria in contaminated food or
water. People with acute illness can contaminate the surrounding water
supply through stool, which contains a high concentration of the
bacteria. Contamination of the water supply can, in turn, taint the food
supply. The bacteria can survive for weeks in water or dried sewage.
3%-5% of people become carriers of the bacteria after the acute
illness. Others suffer a very mild illness that goes unrecognized. These
people may become long-term carriers of the bacteria -- even though
they have no symptoms -- and be the source of new outbreaks of typhoid
fever for many years.
How Is Typhoid Fever Diagnosed?
the ingestion of contaminated food or water, the Salmonella bacteria
invade the small intestine and enter the bloodstream temporarily. The
bacteria are carried by white blood cells in the liver, spleen, and bone
marrow, where they multiply and reenter the bloodstream. People develop
symptoms, including fever, at this point. Bacteria invade the
gallbladder, biliary system, and the lymphatic tissue of the bowel.
Here, they multiply in high numbers. The bacteria pass into the
intestinal tract and can be identified in stool samples. If a test
result isn't clear, blood samples will be taken to make a diagnosis.