Typhoid fever is caused by the bacteria Salmonella typhi or the related bacteria, Salmonella paratyphi.
Typhoid fever can be spread by consuming food or water contaminated with the stool or urine of an infected person.
People have flu-like symptoms, sometimes followed by delirium, cough, exhaustion, occasionally rash, and diarrhea.
Samples of blood, stool, other body fluids, or tissues are sent to a laboratory to grow (culture) the bacteria.
To prevent infection, people traveling to areas where typhoid fever is common should be vaccinated and, when there, should avoid certain foods and not drink unbottled water.
Infected people with or without symptoms are treated with antibiotics.
Typhoid fever is one type of infection caused by salmonella bacteria.
Typhoid fever is common in developing countries where sanitary conditions are poor. Most cases in the United States are acquired while traveling in these countries.
Salmonella typhi is present only in people. People who are infected excrete the bacteria in stool and, rarely, in urine. A few infected people develop chronic infection of the gallbladder or urinary tract. They continue to excrete the bacteria in stool or urine, even though they no longer have any symptoms. Such people are called carriers. Thus, they do not know they can spread the infection. During the early 20th century, one such woman, a cook named Mary Mallon, spread typhoid fever to many people and became known as Typhoid Mary.
The bacteria may contaminate food or drink when hands are inadequately washed after defecation or urination. Water supplies may be contaminated when sewage is inadequately treated. Flies may spread the bacteria directly from stool to food. Occasionally, the infection is spread by direct contact among children during play or between adults during anal-oral sex.
Like all salmonella bacteria, many of these bacteria must be consumed for infection to develop, unless the immune system is impaired or people have a deficiency of stomach acid.
The bacteria spread from the digestive tract to the bloodstream (causing bacteremia) and may infect distant organs such as the liver, spleen, gallbladder, lungs (causing pneumonia), joints (causing infectious arthritis), kidneys (causing pyelonephritis), heart valves (causing endocarditis), genital tract, the tissues covering the brain and spinal cord (causing meningitis), and bone (causing osteomyelitis). These infections develop mainly when people are not treated or when treatment is delayed.
Typically, a flu-like illness begins about 8 to 14 days (up to 30 days) after infection. Typhoid fever symptoms begin gradually. People may have a fever, headache, sore throat, muscle and joint pains, abdominal pains, and a dry cough. They may lose their appetite.
After a few days, the temperature peaks at about 103 to 104° F (39 to 40° C), remains high for another 10 to 14 days, and returns to normal during the fourth week after symptoms started. Often the heartbeat is slow, and people feel exhausted and sometimes become delirious.
During the second week, a rash of flat, rose-colored spots develops on the chest and abdomen of about 10 to 20% of people.
People may be constipated at first, but after 2 weeks, diarrhea may occur. In about 1 to 2% of people, the intestine is torn (perforated) or bleeds. A few people have severe, sometimes life-threatening bleeding.
If infection spreads to other organs, symptoms of those infections may also develop.
In about 8 to 10% of people, symptoms may recur about 2 weeks after the fever goes away.
Without treatment, about 12% of people die. Most people who die are malnourished, very young, or very old. Stupor (unresponsiveness that requires vigorous stimulation to be aroused), coma, and shock are signs of severe infection and a poor prognosis.
To confirm the diagnosis, doctors take samples of blood, stool, urine, other body fluids, or tissues and send them to a laboratory where the bacteria can be grown (cultured). The samples are examined and tested to determine whether the bacteria are present.
Tests to determine which antibiotics are likely to be effective (susceptibility tests) are also done.
People who travel to areas where typhoid fever is common should avoid eating raw vegetables and other foods served or stored at room temperature. Generally, people can safely consume foods that are served very hot immediately after cooking, bottled or canned beverages that are sealed, hot tea or coffee, and fruit that they have peeled themselves. People should assume that ice and water (unless it is boiled or chlorinated before use) are unsafe. Sealed bottled water should be used for brushing teeth.
A vaccine given by mouth and a polysaccharide vaccine given by injection can help prevent typhoid fever. Both vaccines have few side effects. Vaccination is recommended for
People are usually protected for at least 2 years after vaccination by injection and for 5 years after taking the vaccine by mouth. However, they can be infected if many bacteria are ingested. In the United States, 80% of cases of typhoid fever occur in travelers returning from parts of the world where typhoid fever is common. Most of these cases could have been prevented if people had been vaccinated.
When antibiotics are used, fever lasts only 3 to 5 days, rather than 3 to 4 weeks, and the risk of death is reduced to less than 1%. Complete recovery may take weeks or months.
The preferred antibiotics include ceftriaxone given by injection, fluoroquinolones (such as ciprofloxacin, levofloxacin, or moxifloxacin) given by mouth or injection, and azithromycin given by mouth. Chloramphenicol is used worldwide. However, it can damage cells in bone marrow that make blood cells. Also, Salmonella typhi bacteria are becoming increasingly resistant to it.
If the infection is severe, corticosteroids are also given, particularly when people are delirious, comatose, or in shock.
While people have a fever, bed rest is advised. A clear liquid diet can help minimize diarrhea. People should not use aspirin, laxatives, and enemas.
In 10 to 20% of people given antibiotics, the infection recurs, typically about 1 week after treatment is stopped. This infection is milder than the initial illness and is treated the same way.
Carriers must report to the local health department and are prohibited from working with food. Taking antibiotics for 4 to 6 weeks may eradicate the bacteria in many carriers. If carriers have gallbladder disease, surgery to remove the gallbladder may be effective. However, such surgery does not guarantee that the bacteria are eradicated.