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.
The 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 disease.
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.
About 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?
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, 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.
The protean manifestations of typhoid fever make this disease a true diagnostic challenge. The classic presentation includes fever, malaise, diffuse abdominal pain, and constipation. Untreated, typhoid fever is a grueling illness that may progress to delirium, obtundation, intestinal hemorrhage, bowel perforation, and death within 1 month of onset. Survivors may be left with long-term or permanent neuropsychiatric complications.
S typhi has been a major human pathogen for thousands of years, thriving in conditions of poor sanitation, crowding, and social chaos. It may have responsible for the Great Plague of Athens at the end of the Pelopennesian War.[1] The name S typhi is derived from the ancient Greek typhos, an ethereal smoke or cloud that was believed to cause disease and madness. In the advanced stages of typhoid fever, the patient's level of consciousness is truly clouded. Although antibiotics have markedly reduced the frequency of typhoid fever in the developed world, it remains endemic in developing countries.[2]
S paratyphi causes the same syndrome but appears to be a relative newcomer. It may be taking over the typhi niche, in part, because of immunological naivete among the population and incomplete coverage by vaccines that target typhi.
Note that some writers refer to the typhoid and paratyphoid fever as distinct syndromes caused by the typhi versus paratyphi serovars, while others use the term typhoid fever for a disease caused by either one. We use the latter terminology. We refer to these serovars collectively as typhoidal salmonella.
How is typhoid fever spread?
Salmonella Typhi lives only in humans. Persons with typhoid fever carry the bacteria in their bloodstream and intestinal tract. In addition, a small number of persons, called carriers, recover from typhoid fever but continue to carry the bacteria. Both ill persons and carriers shed Salmonella Typhi in their feces (stool).
You can get typhoid fever if you eat food or drink beverages that have been handled by a person who is shedding Salmonella Typhi or if sewage contaminated with Salmonella Typhi bacteria gets into the water you use for drinking or washing food. Therefore, typhoid fever is more common in areas of the world where handwashing is less frequent and water is likely to be contaminated with sewage.
Once Salmonella Typhi bacteria are eaten or drunk, they multiply and spread into the bloodstream. The body reacts with fever and other signs and symptoms.
Where in the world do you get typhoid fever?
Typhoid fever is common in most parts of the world except in industrialized regions such as the United States, Canada, western Europe, Australia, and Japan. Therefore, if you are traveling to the developing world, you should consider taking precautions. Over the past 10 years, travelers from the United States to Asia, Africa, and Latin America have been especially at risk.
How can you avoid typhoid fever?
Two basic actions can protect you from typhoid fever:
Avoid risky foods and drinks.
Get vaccinated against typhoid fever.
It may surprise you, but watching what you eat and drink when you travel is as important as being vaccinated. This is because the vaccines are not completely effective. Avoiding risky foods will also help protect you from other illnesses, including travelers' diarrhea, cholera, dysentery, and hepatitis A.
Symptoms
By Mayo Clinic Staff
Signs and symptoms are likely to develop gradually — often appearing one to three weeks after exposure to the disease.
Early illness
Once signs and symptoms do appear, you're likely to experience:
Fever that starts low and increases daily, possibly reaching as high as 104.9 F (40.5 C)
Headache
Weakness and fatigue
Muscle aches
Sweating
Dry cough
Loss of appetite and weight loss
Abdominal pain
Diarrhea or constipation
Rash
Extremely swollen abdomen
Later illness
If you don't receive treatment, you may:
Become delirious
Lie motionless and exhausted with your eyes half-closed in what's known as the typhoid state
In addition, life-threatening complications often develop at this time.
In some people, signs and symptoms may return up to two weeks after the fever has subsided.
When to see a doctor
See a doctor immediately if you suspect you have typhoid fever. If you become ill while traveling in a foreign country, call the U.S. Consulate for a list of doctors. Better yet, find out in advance about medical care in the areas you'll visit, and carry a list of the names, addresses and phone numbers of recommended doctors.
If you develop signs and symptoms after you return home, consider consulting a doctor who focuses on international travel medicine or infectious diseases. A specialist may be able to recognize and treat your illness more quickly than can a doctor who isn't familiar with these areas.
Typhoid fever is caused by virulent bacteria called Salmonella typhi (S. typhi). Although they're related, S. typhi and the bacteria responsible for salmonellosis, another serious intestinal infection, aren't the same.
Fecal-oral transmission route
The bacteria that cause typhoid fever spread through contaminated food or water and occasionally through direct contact with someone who is infected. In developing nations, where typhoid fever is endemic, most cases result from contaminated drinking water and poor sanitation. The majority of people in industrialized countries pick up typhoid bacteria while traveling and spread it to others through the fecal-oral route.
This means that S. typhi is passed in the feces and sometimes in the urine of infected people. You can contract the infection if you eat food handled by someone with typhoid fever who hasn't washed carefully after using the toilet. You can also become infected by drinking water contaminated with the bacteria.
Typhoid carriers
Even after treatment with antibiotics, a small number of people who recover from typhoid fever continue to harbor the bacteria in their intestinal tracts or gallbladders, often for years. These people, called chronic carriers, shed the bacteria in their feces and are capable of infecting others, although they no longer have signs or symptoms of the disease themselves.
Typhoid fever remains a serious worldwide threat — especially in the developing world — affecting an estimated 26 million or more people each year. The disease is endemic in India, Southeast Asia, Africa, South America and many other areas.
Worldwide, children are at greatest risk of getting the disease, although they generally have milder symptoms than adults do.
If you live in a country where typhoid fever is rare, you're at increased risk if you:
Work in or travel to areas where typhoid fever is endemic
Work as a clinical microbiologist handling Salmonella typhi bacteria
Have close contact with someone who is infected or has recently been infected with typhoid fever
Drink water contaminated by sewage that contains S. typhi
Intestinal bleeding or holes
The most serious complications of typhoid fever — intestinal bleeding or holes (perforations) in the intestine — may develop in the third week of illness. A perforated intestine occurs when your small intestine or large bowel develops a hole, causing intestinal contents to leak into your abdominal cavity and triggering signs and symptoms, such as severe abdominal pain, nausea, vomiting and bloodstream infection (sepsis). This life-threatening complication requires immediate medical care.
Other, less common complications
Other possible complications include:
Inflammation of the heart muscle (myocarditis)
Inflammation of the lining of the heart and valves (endocarditis)
Pneumonia
Inflammation of the pancreas (pancreatitis)
Kidney or bladder infections
Infection and inflammation of the membranes and fluid surrounding your brain and spinal cord (meningitis)
Psychiatric problems, such as delirium, hallucinations and paranoid psychosis
With prompt treatment, nearly all people in industrialized nations recover from typhoid fever. Without treatment, some people may not survive complications of the disease