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.
Typhoid fever is rare in industrialized countries. However, it remains a serious health threat in the developing world, especially for children.
If typhoid is caught early, it can be successfully treated with antibiotics; if it is not treated, typhoid can be fatal. If untreated, around 1 in 4 cases of typhoid end in death. If treatment is given, less than 4 in 100 cases are fatal.
In the developing world, however, typhoid is a much more common risk. Globally, in 2010, there were 26.9 million reported cases and around 200,000 reported deaths from typhoid.
How Do People Get Typhoid Fever?
The bacterium that causes typhoid fever may be spread through poor hygiene habits and public sanitation conditions, and sometimes also by flying insects feeding on faeces. Public education campaigns encouraging people to wash their hands after defecating and before handling food are an important component in controlling spread of the disease.
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.
Transmission through sexual contact, especially among men who have sex with men, has been documented rarely.
No animals carry this disease, so transmission is always human to human.
Faecal-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 travelling and spread it to others through the faecal-oral route.
This means that S. typhi is passed in the faeces 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.
Even after treatment with antibiotics, a small number of people who recover from typhoid fever continue to harbour the bacteria in their intestinal tracts or gallbladders, often for years. These people, called chronic carriers, shed the bacteria in their faeces and are capable of infecting others, although they no longer have signs or symptoms of the disease themselves.
Sanitation and hygiene are important to prevent typhoid. Typhoid does not affect animals other than humans. Typhoid can only spread in environments where human faeces or urine are able to come into contact with food or drinking water. Careful food preparation and washing of hands are crucial to prevent typhoid.
Wash your hands. Frequent hand-washing in hot, soapy water is the best way to control infection. Wash before eating or preparing food and after using the toilet. Carry an alcohol-based hand sanitizer for times when water isn't available.
Avoid drinking untreated water. Contaminated drinking water is a particular problem in areas where typhoid fever is endemic. For that reason, drink only bottled water or canned or bottled carbonated beverages, wine and beer. Carbonated bottled water is safer than un-carbonated bottled water is.
Ask for drinks without ice. And if you must take ice, be sure of its source to be safe. Use safe drinking water to brush your teeth, and try not to swallow water in the shower.
Wash raw fruits and vegetables thoroughly with safe water. Because raw produce may have been washed in unsafe water, avoid fruits and vegetables that you can't peel if you are not sure of the water used in washing it.
Choose hot foods. Avoid food that's stored or served at room temperature. Steaming hot foods are best. And although there's no guarantee that meals served at the finest restaurants are safe, it's best to avoid food from street vendors — it's more likely to be contaminated.
Who Is At Risk?
Typhoid fever is most common in parts of the world that have poor sanitation and limited access to clean water.
Worldwide, children are thought to be most at risk of developing typhoid fever. This may be because their immune system (the body's natural defence against infection and illness) is still developing. However, children with typhoid fever tend to have milder symptoms than adults.
Typhoid fever is rare in industrialized regions such as the United States, Canada, Western Europe, Australia, and Japan, so travellers to the developing world should consider taking precautions. Travellers to Asia, Africa, and Latin America are especially at risk, and the highest risk for typhoid is in South Asia.
The areas with the highest rates of typhoid fever are:
the Indian subcontinent
South and South East Asia
the Middle East
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 re-enter 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.
Typhoid is diagnosed by detecting the presence of S. typhi via blood, stool, urine, or bone marrow sample.
What Are The Symptoms Of Typhoid Fever?
Signs and symptoms are likely to develop gradually — often appearing one to three weeks after exposure to the disease.
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)
Weakness and fatigue
Loss of appetite and weight loss
Diarrhoea or constipation
Extremely swollen abdomen
If you don't receive treatment, you may:
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.
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)
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.
How Is Typhoid Fever Treated?
Typhoid fever is treated with antibiotics which 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 is guided by identifying the geographic region where the infection was contracted (certain strains from South America show a significant resistance to some antibiotics.) If relapses occur, patients are retreated with antibiotics.
Those who become chronically ill (about 3%-5% of those infected), can be treated with prolonged antibiotics. Often, removal of the gallbladder, the site of chronic infection, will provide a cure.
For those travelling to high-risk areas, vaccines are now available.
Typhoid Fever At A Glance
Typhoid fever 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 are 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.