Typhoid fever is an infection caused by Salmonella enterica subtype typhi (abbreviated by the CDC to Salmonella typhi), a bacteria that grows only in the digestive systems and bloodstreams of humans. People who are infected with S. typhi can shed the bacteria in their stools, and people who are not infected can pick up S. enterica typhi from the stools of infected people or from eating or drinking food or liquids that have been contaminated with the stools of infected people. After ingesting S. typhi, the bacteria begin to multiply in your body.
Actual contact and ingestion of stools is very rare (thank goodness). Eating or drinking something contaminated with an infected person's stools is not rare at all. Outbreaks of typhoid fever are occasionally seen in developed areas with clean water supplies and good sewage systems, but are quite common in developing countries where the water used for drinking and washing is not clean and all too often comes in contact with sewage.
People infected with S. typhi usually have a fever (thus the term typhoid fever) -- sometimes up to 103-104 degrees F. Often they have abdominal pains, loss of appetite, headaches, malaise (feeling lousy) and may feel weak as well. Some patients develop a rash that consists of reddish macules (flat spots). These symptoms and signs aren't all that uncommon, and typhoid fever can be diagnosed only by testing the patient's stool for S. typhi.
If left untreated, typhoid fever can last for up to 4 weeks, and from 12 to 30% of infected and untreated patients may die of the infection. About 1 in 20 infected people become carriers who continue to shed the bacteria, sometimes for over a year after their apparent "recovery".
Treatment with antibiotics -- usually ampicillin, trimethoprim/sulfamethoxazole, azithromycin, or ciprofloxacin -- will usually start relieving the symptoms in 2-3 days, although a full course of antibiotics (10-14 days) must be taken for complete treatment. Your doctor may choose the antibiotic based on cultures of your particular S. typhi. Sometimes S. typhi is resistant to several different antibiotics, and a patient with a multiply-resistant strain may need two or more different antibiotics at the same time. 10-15% of patients relapse after antibiotic treatment, and may need to be retreated with different antibiotics; relapse is more likely if you do not finish the original antibiotics as they were prescribed for you. People who are carriers may need to be treated a little differently. Some adults with gallstones are more prone to becoming carriers and may need to have their gall bladders removed.
As with any disease, the best treatment is not to get sick in the first place. There are currently two vaccines available in the United States against S. typhi. One is an injectable vaccine made from the capsule that surrounds the bacteria's cells: this is given in a single dose, gives you immunity for about 2 years (you need another booster dose after that time), and works in children as young as 2 years. The other is an oral vaccine consisting of live but weakened S. typhi and comes as a set of four capsules. To use this vaccine you must take one capsule every other day for four days, each one about 1 hour before eating (you have to keep each capsule in the refrigerator until you take it). This vaccine works only down to age 6 years, and must be boosted every 5 years. You should finsh the oral vaccine at least 1 week before entering an area where typhoid is common; the injectable vaccine takes 2 weeks to give full protection.
Although the vaccines provide some protection against typhoid fever, they are not perfect. You should get the vaccine before going to an area where S. typhi is prevalent -- in other words, most developing countries -- but you should still be careful about what you eat or drink. The safest rule is "boil it, peel it, cook it, or forget it":