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What is typhoid fever?

Typhoid fever is an acute illness associated with fever that is most often caused by the Salmonella typhi bacteria. It can also be caused by Salmonella paratyphi, a related bacterium that usually leads to 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.

The incidence of typhoid fever in the United States has markedly decreased since the early 1900s. Today, approximately 400 cases are reported annually in the United States, mostly in people who recently have traveled to endemic areas. This is in comparison to the 1920s, when over 35,000 cases were reported in the U.S. This improvement is the result of improved environmental sanitation. Mexico and South America are the most common areas for U.S. citizens to contract typhoid fever. India, Pakistan, and Egypt are also known high-risk areas for developing this disease. Worldwide, typhoid fever affects more than 13 million people annually, with over 500,000 patients dying of the disease.

If traveling to endemic areas, you should consult with your health-care professional and discuss if you should receive vaccination for typhoid fever.
How do patients get typhoid fever?

Typhoid fever is contracted by the ingestion of the bacteria in contaminated food or water. Patients 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. About 3%-5% of patients become carriers of the bacteria after the acute illness. Some patients suffer a very mild illness that goes unrecognized. These patients can become long-term carriers of the bacteria. The bacteria multiplies in the gallbladder, bile ducts, or liver and passes into the bowel. The bacteria can survive for weeks in water or dried sewage. These chronic carriers may have no symptoms and can be the source of new outbreaks of typhoid fever for many years.

How does the bacteria cause disease, and how is it diagnosed?

After 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. The bacteria then multiply in the cells of these organs and reenter the bloodstream. Patients develop symptoms, including fever, when the organism reenters the bloodstream. 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 for diagnosis in cultures from the stool tested in the laboratory. Stool cultures are sensitive in the early and late stages of the disease but often must be supplemented with blood cultures to make the definite diagnosis.

What are the symptoms of typhoid fever?

The incubation period is usually one to two weeks, and the duration of the illness is about four to six weeks. The patient experiences

poor appetite,


headaches,


generalized aches and pains,


fever,


lethargy,


diarrhea.

People with typhoid fever usually have a sustained fever as high as 103 F-104 F (39 C-40 C).

Chest congestion develops in many patients, and abdominal pain and discomfort are common. The fever becomes constant. Improvement occurs in the third and fourth week in those without complications. About 10% of patients have recurrent symptoms (relapse) after feeling better for one to two weeks. Relapses are actually more common in individuals treated with antibiotics.
How is typhoid fever treated, and what is the prognosis?

Typhoid fever is treated with antibiotics that kill the Salmonella bacteria. Prior to the use of antibiotics, the fatality rate was 20%. Death occurred from overwhelming infection, pneumonia, intestinal bleeding, or intestinal perforation. With antibiotics and supportive care, mortality has been reduced to 1%-2%. With appropriate antibiotic therapy, there is usually improvement within one to two days and recovery within seven to 10 days.

Several antibiotics are effective for the treatment of typhoid fever. Chloramphenicol was the original drug of choice for many years. Because of rare serious side effects, chloramphenicol has been replaced by other effective antibiotics. The choice of antibiotics needs to be guided by identifying the geographic region where the organism was acquired and the results of cultures once available. (Certain strains from South America show a significant resistance to some antibiotics.) Ciprofloxacin (Cipro), ampicillin (Omnipen, Polycillin, Principen), and trimethoprim-sulfamethoxazole (Bactrim, Septra) are frequently prescribed antibiotics. If relapses occur, patients are retreated with antibiotics.

The carrier state, which occurs in 3%-5% of those infected, can be treated with prolonged antibiotics. Often, removal of the gallbladder, the site of chronic infection, will cure the carrier state.

For those traveling to high-risk areas, vaccines are now available.
Typhoid Fever At A Glance

Typhoid fever usually is caused by Salmonellae typhi bacteria.
Typhoid fever is contracted by the ingestion of contaminated food or water.
Diagnosis of typhoid fever is made when the Salmonella bacteria is detected with a stool culture.
Typhoid fever is treated with antibiotics.
Typhoid fever symptoms are poor appetite, headaches, generalized aches and pains, fever, and lethargy.
Approximately 3%-5% of patients become carriers of the bacteria after the acute illness.

REFERENCE:

United States. Centers for Disease Control and Prevention. "Typhoid Fever." Oct. 24, 2005. .