Typhoid Fever

Typhoid fever (enteric fever) is caused by the gram-negative bacilli Salmonella typhi and is characterized by prolonged fever, abdominal pain, and a rash.
Salmonella typhi is passed in the stool and urine of infected people. Inadequate hand washing after defecation or urination may spread the bacteria to food or drink; inadequate treatment of sewage may lead to contamination of water supplies. Flies may spread the bacteria directly from
stool to food. Rarely, hospital workers who have not taken adequate precautions develop typhoid fever after handling soiled bed linens or contaminated bandages from infected people.
About 3% of the infected people who do not receive treatment continue to pass bacteria in their stool for more than a year. Some of these carriers never have symptoms. Most of the carriers are older women with chronic gallbladder disease. In the past, one such woman (a cook named Mary Mallon) was responsible for spreading typhoid fever to numerous people and became
known as Typhoid Mary.
Typhoid bacteria enter the digestive tract and gain access to the bloodstream. Inflammation of the small and large intestine follows. In severe infections, which can be life threatening, sores may develop in the small intestine. These sores bleed and sometimes perforate the intestinal
wall.

Symptoms and Diagnosis
Usually, symptoms begin gradually 8 to 14 days after infection. The first symptoms include loss of appetite, fever, headache, joint pain, sore throat, constipation (or, less commonly, diarrhea), and abdominal pain and tenderness. A brassy, nonproductive cough is common. Nosebleed may occur.
As the illness progresses, fever remains high, and the person may become delirious. This sustained fever is often accompanied by a slow heartbeat and extreme exhaustion. Diarrhea may continue, although some people become constipated. In about 10% of infected people, clusters of small, pink spots appear on the chest and abdomen during the second week and last 2 to 5 days. After 2 weeks, intestinal bleeding or perforation occurs in 3 to 5% of infected people.
Pneumonia may develop during the second or third week and usually results from a pneumococcal infection, although typhoid bacteria can also cause pneumonia. Infection of the gallbladder and liver also may occur. A blood infection (bacteremia) occasionally leads to infection of bones (osteomyelitis) , heart valves (endocarditis) , kidneys (glomerulitis) , the
genitourinary tract, or the tissues covering the brain and spinal cord (meningitis) . Infection of muscles may lead to abscesses (collections of pus).
Although the history and symptoms of illness may suggest typhoid fever, the diagnosis must be confirmed by identifying the bacteria in cultures of blood, stool, urine, or other body fluids or tissues.

Prevention and Treatment
People who travel to areas where typhoid fever is common should avoid eating raw vegetables and other foods served or stored at room temperature. Foods served very hot, bottled carbonated beverages, and raw foods that can be peeled are generally safe. Unless water is known to be safe, it should be boiled or chlorinated before being used for drinking or brushing teeth. Both oral and injectable vaccines against typhoid fever are available, but they provide only partial protection. The vaccine is given only to people who have been exposed to the bacterium and to those who are at high risk of exposure, including laboratory workers studying the organism and people traveling to areas where the disease is common.
With prompt antibiotic therapy, more than 99% of the people with typhoid fever are cured, although convalescence may last several months. The antibiotic chloramphenicol is used worldwide, but increasing resistance to it has prompted the use of other antibiotics (such as trimethoprim- sulfamethoxazole or ciprofloxacin) . If the person is delirious, comatose, or in shock, corticosteroids may be given to reduce brain inflammation. Typically, people who die are malnourished, very young, or very old. Stupor, coma, and shock are signs of severe infection and a poor prognosis.
People who recover do so in 3 to 4 weeks. Between 10% and 30% of untreated people with typhoid fever die. In about 10% of untreated people, symptoms of the initial infection recur 2 weeks later. For unknown reasons, antibiotics taken during the initial illness increase the recurrence rate to 15 to 20%. If antibiotics are given for the relapse, the fever goes away much more quickly than in the original illness, but occasionally another relapse occurs.
Relapses are treated the same way as the initial illness, but antibiotics are usually needed for only 5 days. Carriers (people who do not have symptoms but who pass the bacteria in their stool) must report to the local health department and are prohibited from working with food. The bacteria may be eradicated in many carriers after 4 to 6 weeks of antibiotic therapy.
(Merck)