Typhoid Fever is a bacterial infection caused by Salmonella enterica serovar Typhi. This organism is unique among Salmonella because it is restricted solely to human hosts, meaning there is no animal reservoir. Once a common global threat, the infection now primarily affects regions with limited public health infrastructure and inadequate sanitation. The disease poses a burden, with an estimated 9 million people falling ill and 110,000 deaths occurring annually worldwide.
Understanding Transmission Pathways
The spread of S. typhi occurs almost exclusively through the fecal-oral route. The bacteria are ingested via food or water contaminated by the feces of an infected person. In environments lacking proper sanitation, human waste can easily compromise drinking water sources, leading to widespread outbreaks.
Contamination results from poor hygiene practices among food handlers or from using contaminated water to wash or prepare food. The bacteria can persist in the environment long enough to facilitate transmission. A challenge in controlling the disease is the existence of chronic asymptomatic carriers.
These carriers (typically 2–5% of those infected) continue to shed the bacteria in their stool for over a year, often harboring the organism within the gallbladder. They act as a persistent reservoir, unknowingly spreading the infection even after their symptoms have resolved or if they never experienced acute illness. Identifying and treating these carriers is an important strategy in curbing long-term transmission.
Recognizing the Clinical Stages of Infection
The progression of Typhoid Fever is divided into distinct weekly stages following an incubation period ranging from six to thirty days. The first week is marked by an insidious onset, beginning with malaise and a characteristic “step-ladder” pattern of fever, where the temperature rises gradually each day. A relative bradycardia (a slower than expected heart rate despite the high fever) is a distinct physical sign present during this initial phase.
By the second week, the fever becomes sustained at a high plateau, often reaching 103–104°F. Abdominal symptoms, including distention, pain, and either severe constipation or “pea soup” diarrhea, become pronounced as the bacteria multiply within the intestinal lymphoid tissue. A transient, sparse rash called “rose spots” may appear on the trunk and abdomen in a minority of patients, consisting of small, pink, blanching maculopapules.
The third week of untreated illness can lead to the most severe complications, as the patient becomes severely ill, sometimes entering a state of apathy and confusion known as the “typhoid state.” Necrosis of the Peyer’s patches in the small intestine can lead to intestinal hemorrhage or perforation. These events necessitate immediate medical intervention and are the main causes of death in untreated cases.
Diagnosis and Medical Management
Confirming a diagnosis of Typhoid Fever relies on isolating S. typhi from a clinical specimen. Blood culture is considered the gold standard, especially during the first week when the bacteria are circulating in the bloodstream. Stool or urine cultures can be used later in the disease course, though their sensitivity is lower than that of blood or bone marrow cultures.
Antibiotic therapy is the only effective treatment, and supportive care is necessary to manage dehydration and nutritional needs. Historically, first-line treatments included ampicillin, chloramphenicol, and trimethoprim-sulfamethoxazole. However, the emergence of Antimicrobial Resistance (AMR) has complicated management over the past decades.
Many strains are now Multidrug Resistant (MDR), showing resistance to all three traditional first-line drugs. Fluoroquinolone non-susceptibility (FQNS) is widespread, particularly in high-incidence areas like South Asia, forcing clinicians to rely on macrolides (such as azithromycin) or third-generation cephalosporins. The recent rise of Extensively Drug Resistant (XDR) strains, which are resistant to most common antibiotics, has made treatment challenging, sometimes requiring the use of carbapenems like meropenem.
Prevention Through Vaccination and Hygiene
Preventative strategies focus on improving public health infrastructure and utilizing immunization. Access to safe water, adequate sanitation, and good hygiene practices (the WASH protocol) form the foundation of long-term control. This includes meticulous handwashing and ensuring food is cooked thoroughly, served hot, or peeled before consumption.
Vaccination provides protection, especially for travelers and those living in endemic regions. The older vaccines include the injectable Vi polysaccharide vaccine (Vi-PS) and the oral live-attenuated Ty21a vaccine, which require multiple doses or boosters. The newer Typhoid Conjugate Vaccine (TCV) is the preferred option, offering longer-lasting immunity and suitability for children as young as six months of age.
The World Health Organization recommends the TCV for routine immunization in countries with a high burden of the disease due to its improved performance and single-dose simplicity. Combining these vaccine programs with consistent efforts to ensure safe drinking water and food preparation is the most effective approach to reducing the global incidence of Typhoid Fever.