Open Outbreak

Typhoid fever

Also known as: Salmonella Typhi, enteric fever, XDR typhoid

Typhoid fever is a bacterial infection caused by Salmonella enterica serovar Typhi, usually shortened to Salmonella Typhi. People get it by swallowing food or water contaminated with human feces or urine from an infected person or a healthy carrier. It is not known to have an animal reservoir; humans are the main reservoir described in the sources. Symptoms usually start about 1 to 3 weeks after exposure, though one source gives a wider range of 6 to 30 days. Illness can be mild or severe and commonly includes high fever, headache, weakness, belly pain, constipation or diarrhea, and sometimes a faint rash. Antibiotics can treat typhoid fever, but drug resistance is a growing problem, including extensively drug-resistant strains reported in Pakistan. Vaccines exist, and WHO reporting and a Cochrane review describe typhoid conjugate vaccine as the preferred option, alongside older oral and injectable vaccines. The disease is most strongly associated with places where safe water, sanitation, and hygiene are inadequate.

Key facts

TransmissionFood or drink contaminated with feces or urine from infected people or carriers; healthy carriers can continue to spread it.
IncubationUsually 1–3 weeks after exposure; one overview source says 6–30 days.
Case fatalityunknown
Reproduction numberunknown
VaccineAvailable. Sources describe oral Ty21a, injectable Vi polysaccharide, and typhoid conjugate vaccine (TCV); WHO-related sources describe TCV as the preferred vaccine.
TreatmentAntibiotics are used, but resistance to common antimicrobials is widespread; XDR strains reported in Pakistan were resistant to first- and second-line antibiotics and third-generation cephalosporins.
ReservoirHumans
Endemic regionsHighest burden described in south-central and southeast Asia; outbreaks are also reported in parts of Africa and elsewhere where water and sanitation are unsafe.

Transmission

Typhoid fever spreads through the fecal-oral route. In plain language, that means people become infected by swallowing food or water contaminated with stool, or sometimes urine, from an infected person. WHO’s Uganda outbreak notice says contaminated drinking water and juices were identified as the main sources there. The same WHO notice also warns that healthy carriers can remain after acute illness and should be kept away from food handling, because they can still pass the bacteria on. An overview source says symptoms usually begin 6 to 30 days after exposure, while WHO describes a usual incubation of 1 to 3 weeks. The sources used here describe humans, not animals, as the reservoir for Salmonella Typhi. This is why safe water, sewage control, hand hygiene, and food safety matter so much for prevention.

Symptoms and severity

Typhoid fever often begins gradually. WHO lists high fever, malaise, headache, constipation or diarrhea, rose-coloured spots on the chest, and an enlarged spleen and liver. The overview source adds weakness, abdominal pain, mild vomiting, and in severe cases confusion. Symptoms can be mild or severe. In outbreaks, some patients develop serious complications: WHO’s 2023 notice from the Republic of the Congo described many suspected cases and noted an unusually high number of patients needing surgery for intestinal perforation, a dangerous bowel complication. The same notice reported 52 deaths among 2,389 suspected cases in that mixed outbreak of suspected typhoid fever, shigellosis, and cholera, but that figure does not give a clean typhoid-only fatality rate. Because the sources returned here do not provide a clear general typhoid case-fatality estimate, the case fatality is listed as unknown.

Treatment and vaccines

Typhoid fever can be treated with antibiotics, but the choice of drug has become harder because resistance is widespread. WHO’s Uganda notice states plainly that typhoid can be treated with antibiotics, while the 2015 review on invasive Salmonella infections says resistance emerged first to older first-line drugs and later to fluoroquinolones. WHO’s Pakistan outbreak report shows why this matters: the XDR strain circulating there was resistant to first- and second-line antibiotics and also to third-generation cephalosporins. Prevention by vaccination is therefore important. A 2018 Cochrane review says two older vaccines are widely available: the oral Ty21a vaccine and the injectable Vi polysaccharide vaccine. The same review notes that WHO had recommended a Vi tetanus toxoid typhoid conjugate vaccine, Typbar-TCV, as the preferred vaccine. Pakistan’s outbreak report also describes emergency use and wider rollout plans for typhoid conjugate vaccine.

Where it occurs

Typhoid fever is strongly linked to places where access to safe water, sanitation, and hygiene is poor. The 2004 global burden paper says typhoid and paratyphoid remain important causes of illness and death, particularly among children and adolescents in south-central and southeast Asia. WHO outbreak notices in this session show that the disease is not limited to one region. WHO documented outbreaks in Uganda in 2015 and in the Republic of the Congo in 2023, both linked to unsafe water and sanitation problems. The Pakistan report from 2018 describes a large outbreak of extensively drug-resistant typhoid in Sindh province and also notes travel-associated cases detected in the United Kingdom and the United States after travel to Pakistan. That does not mean typhoid is established in those countries; it shows that international travel can export cases from outbreak areas.

Recent history

On this site’s archive, typhoid has appeared in 8 WHO-related outbreak entries since 1996. The history list returned in this session includes notices for Algeria in 1996, Tajikistan in 1996 and 1997, Kyrgyzstan in 1998, Haiti in 2003, Democratic Republic of the Congo in 2004, Uganda in 2015, and Pakistan in 2018. More recently, WHO published a 2023 notice on a suspected triple outbreak in the Republic of the Congo that included Salmonella Typhi among the confirmed causes. The 2018 Pakistan report is especially important because it describes a prolonged outbreak of extensively drug-resistant typhoid beginning in 2016, with 5,274 XDR cases among 8,188 typhoid cases reported in Sindh province through 2018. Overall, the archive suggests typhoid repeatedly reappears as a water-and-sanitation disease, with antimicrobial resistance becoming a bigger part of the story in recent years.

What to watch

The clearest warning signs are practical ones. First, watch for spread into new regions, especially where health systems are not expecting typhoid, or for more travel-associated cases linked to one outbreak source. Second, watch for more evidence of antimicrobial resistance. WHO’s Pakistan report shows that XDR typhoid can remove several standard treatment options at once, so any reports of resistance spreading geographically or into new lineages would be concerning. Third, watch for breakdowns in water, sanitation, and food safety after floods, displacement, or urban service failures, because WHO reports link these directly to outbreaks. Fourth, watch vaccine supply and coverage. WHO reporting from Pakistan and the Cochrane review both point to typhoid conjugate vaccine as an important control tool. If vaccine campaigns stall, coverage drops, or supplies tighten in high-burden settings, outbreak risk could rise.

Updated