Typhoid fever

Typhoid fever, also known simply as typhoid, is a bacterial infectious disorder caused by Salmonella enterica subsp. enterica serovar Typhi. The organism is strictly adapted to human hosts and does not infect other animals. The disease is contracted through the oral ingestion of contaminated food or water and represents one of the enteric fevers, alongside paratyphoid fever. The bacterium exhibits a predilection for the intestinal lymphoid tissue, including Peyer's patches, as well as the mesenteric lymph nodes, spleen, liver, gallbladder, bone marrow, and bloodstream.

Clinical manifestations range from mild to severe, with an incubation period typically spanning six to thirty days following exposure. The illness classically presents with a gradual onset of sustained high fever accompanied by constitutional symptoms including weakness, headache, and abdominal discomfort. Gastrointestinal manifestations commonly include constipation rather than diarrhea, though diarrhea may occur in some cases and can be severe when present. A characteristic rose-colored skin rash may develop in certain patients. Neurological complications such as confusion may emerge in severe cases. Without appropriate antimicrobial treatment, the symptomatic phase may persist for weeks or months. A notable epidemiological feature is the existence of asymptomatic carriers who harbor the bacterium and remain contagious despite lacking clinical illness.

Typhoid fever is endemic in developing countries where access to clean drinking water is limited and sanitation infrastructure is inadequate. The disease burden falls disproportionately on populations with these environmental risk factors. Global phylogeographical analysis has identified haplotype 58 (H58), now designated as genotype 4.3.1, as the dominant circulating strain; this haplotype emerged in India during the late 1980s and has disseminated worldwide in association with multi-drug resistance. Humans serve as the exclusive reservoir for S. Typhi, and transmission is maintained through both acute clinical cases and chronic asymptomatic carriers who may excrete the organism in stool for extended periods following recovery.

The primary mode of transmission is the fecal-oral route, occurring through consumption of food or water contaminated with fecal matter from infected individuals. Both symptomatic patients and asymptomatic carriers contribute to environmental contamination. The risk of infection is highest among individuals who have not previously been exposed to the pathogen and who consume contaminated drinking water or food. Poor sanitation conditions and limited access to potable water facilitate the perpetuation of transmission cycles within affected communities.

Populations with limited access to clean drinking water and inadequate sanitation facilities face the highest risk of typhoid fever acquisition. Individuals without prior exposure to S. Typhi who consume contaminated water or food in endemic areas are particularly susceptible. Household contacts of infected individuals may also be at elevated risk due to shared environmental exposures and potential carrier status among family members.

Prevention strategies center on ensuring access to safe drinking water and improving sanitation infrastructure to interrupt fecal-oral transmission. Antibiotic therapy is effective for treatment of active infection, though the emergence of multi-drug resistant strains, including the H58 haplotype, complicates therapeutic management. Public health measures targeting carrier identification and hygiene education in affected communities represent important supplementary prevention approaches.

Surveillance for typhoid fever should account for the disease's focal distribution in areas with inadequate water and sanitation infrastructure. The presence of asymptomatic carriers complicates case identification and outbreak source attribution. Laboratory confirmation relies on blood, bone marrow, or stool cultures, with the Widal test providing serological support in resource-limited settings where culture capacity may be constrained. Monitoring for antimicrobial resistance patterns is essential given the documented global spread of resistant haplotypes.

1. 1 WHO Health Topics. Health topics.
2. 2 WHO Q&A. News.
3. 3 Wikidata. typhoid fever.
4. 4 Wikipedia. Typhoid fever - Wikipedia.

ICD-10

ICD-11

Total cases

4K

Peak month

2025-02

Coverage

3 reporting countries · 2000-01-01 → 2026-05-09