Typhoid fever is a systemic illness caused by the bacterium Salmonella enterica serotype Typhi (S. Typhi). This infection is a type of enteric fever, affecting the intestinal tract before spreading throughout the body. If not treated promptly, the condition can result in severe complications or death. Typhoid remains a significant public health challenge globally, especially where sanitation and clean water access are limited.
The Spread of Salmonella Typhi
Transmission of S. Typhi occurs almost exclusively through the fecal-oral route, where bacteria pass from the feces of an infected person to the mouth of another. This spread is directly related to poor sanitation and hygiene practices. When human waste contaminates water sources or food supplies, the bacteria can easily be ingested.
The bacterium is resilient and can survive in water and sewage for extended periods, creating an environmental reservoir. Contaminated water is a frequent vehicle for transmission, but food can also become contaminated, especially if handled by an infected person who has not washed their hands thoroughly.
A distinct feature of typhoid fever is the existence of asymptomatic carriers, individuals who harbor the bacteria but show no symptoms. These carriers continue to shed S. Typhi in their stool, sometimes for years, becoming silent vectors of the disease. This carrier state is a major factor in the persistence and spread of typhoid, particularly in endemic areas.
Clinical Progression and Symptoms
After ingesting the bacteria, the incubation period typically ranges from one to three weeks before symptoms appear. The onset is usually gradual, making it difficult to distinguish from a common viral infection early on. The disease’s progression is classically described in stages, each lasting about a week.
During the first week, a characteristic symptom is a slow, rising fever that increases daily and can reach up to 104°F (40°C). This high fever is often accompanied by headache, malaise, weakness, and a dry cough. Abdominal discomfort and constipation are also common early complaints.
By the second week, the fever tends to plateau at consistently high levels, and the patient becomes severely fatigued. A faint, temporary rash known as “rose spots” may appear on the lower chest and abdomen in a small percentage of cases. These small, salmon-colored, blanching spots are caused by the bacteria spreading throughout the bloodstream.
If the illness progresses into the third week without treatment, severe complications arise. The infection can lead to delirium, historically called the “typhoid state,” marked by confusion and apathy. Intestinal complications, such as internal bleeding or bowel perforation, represent the most serious risks during this phase.
Medical Diagnosis and Treatment
Confirming typhoid fever requires isolating the S. Typhi bacteria in a laboratory setting. The gold standard for diagnosis, especially early in the illness, is a blood culture. A blood sample is taken and incubated to identify the presence of the organism in the bloodstream.
As the disease progresses, the bacteria can also be isolated from other body fluids, making stool or bone marrow cultures valuable diagnostic tools. Bone marrow cultures are highly sensitive and often remain positive even after antibiotic treatment begins. Serological tests, such as the Widal test, detect the body’s antibody response but are often less accurate than cultures, particularly where the disease is common.
Antibiotic therapy is the only effective treatment for typhoid fever and must be started quickly to prevent complications. Fluoroquinolones, such as ciprofloxacin, were once the first-line choice. However, the rise of multidrug-resistant (MDR) S. Typhi has significantly complicated treatment protocols.
MDR strains resist older antibiotics like chloramphenicol, ampicillin, and trimethoprim-sulfamethoxazole. The emergence of extensively drug-resistant (XDR) strains, which also resist fluoroquinolones and third-generation cephalosporins, necessitates using macrolides like azithromycin or carbapenems for severe cases. The antibiotic choice is determined by the geographic region of infection and local resistance patterns.
Methods of Prevention
Prevention relies on improving public health infrastructure and providing individual protection through vaccination. Access to safe drinking water and adequate sanitation (WASH: Water, Sanitation, and Hygiene) is the foundation for reducing typhoid transmission. This includes proper sewage disposal to prevent water source contamination.
Individual protective measures focus on personal hygiene, especially thorough handwashing after using the restroom and before handling food. Travelers to endemic regions should follow the rule: “Boil it, cook it, peel it, or forget it.” This means avoiding untreated water, unpasteurized dairy products, and raw or undercooked foods.
Vaccination offers an additional layer of protection, especially for travelers or those living in endemic areas. Two main types of vaccines are available: an oral live-attenuated vaccine and injectable vaccines (polysaccharide or conjugate varieties). The injectable polysaccharide vaccine is typically recommended for those two years of age and older, while newer typhoid conjugate vaccines can be given to children as young as six months.