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NCID > For Healthcare Professionals > Diseases and Conditions > Typhoid and Paratyphoid Fever

Typhoid and Paratyphoid Fever

Typhoid and Paratyphoid Fever

Causative Agents

Salmonella typhi (Typhoid fever)
Salmonella paratyphi A, B and C (Paratyphoid fever).

Incubation Period

1 - 3 weeks

Infectious Period

During acute infection and until stool and urine clearance.


Faeco-oral route through contaminated food or water. Transmission through sexual contact, especially among men who have sex with men have been documented.
There is no animal reservoir so ultimately the disease always involves human-to- human spread.


During the period 2005-2009, there were 349 reported cases of typhoid (94% imported) and 139 reported cases of paratyphoid (88.5% imported). The disease is endemic in Southeast Asia and the Indian subcontinent.

  • Typhoid fever
    • 1st week of illness: Rising, “stepwise” fever, bacteraemia and diarrhoea (78% of children) or constipation (more frequent in adults).
    • 2nd week of illness: Abdominal pain and rash (rose spots)
    • 3rd week of illness: Hepatosplenomegaly, intestinal bleeding and perforation
  • Complications (rare if diagnosed and treated early)
    • Intestinal haemorrhage or perforation
    • Toxic myocarditis
    • Confusion, convulsions, encephalitis
    • Haemolytic anaemia (especially in G6PD deficiency)
    • Renal failure
    • Abscesses in liver, spleen, bone etc.
  • Paratyphoid fever
    • Maybe clinically mild or asymptomatic
    • Nausea, vomiting, fever, diarrhoea, and cramping—usually occur within 8 to 72 hours of ingesting contaminated food or water
    • Less than 5% of non-typhoidal salmonella gastroenteritis develop bacteraemia and may result in extra-intestinal manifestations including endocarditis, mycotic aneurysm and osteomyelitis.

  • Blood test frequently show anaemia, elevated hepatic transaminases and either leucopoenia or leucocytosis.
  • Isolation of organism is the gold standard for diagnosis.
  • Blood culture usually positive for 1st two weeks only.
  • Stool and urine culture positive from 2nd to 4th weeks.
  • The yield from bone marrow culture is high and is usually positive even after antibiotics have been initiated.
  • The Widal test is unreliable in itself, but may provide additional support for the diagnosis when the clinical picture is suggestive.

A legally notifiable disease in Singapore. Notify Ministry of Health (Form MD 131 or electronically via CD-LENS) not later than 24 hours from the time of diagnosis.


  • Patients should be hospitalised during antibiotic treatment.
  • Rehydration and other supportive care.
  • Current drugs of choice:
    • PO Ciprofloxacin 500 mg bd x 7-10 days (if sensitive to ciprofloxacin andnalidixic acid)
    • IV Ceftriaxone 2-3g once daily x 10-14 days
    • Alternative: PO Azithromycin 1g once then 500mg once daily x 5-7 days
    • N.B. 70-90 % of isolates in some parts of Nepal, India and Vietnam are nalidixic acid resistant strains.
  • Dexamethasone 3mg/kg then 1mg/kg 6 hourly x 8 doses for severe typhoid fever (as suggested by delirium, shock and altered mental status) decreases mortality.
  • Relapse rate 1-6% with newer antibiotics (10-25% with chloramphenicol)
  • One to four percent of adults become chronic carriers despite antibiotics.
  • Follow-up stool evaluation to document stool clearance after treatment:
    • Three consecutive stool samples taken at weekly intervals no sooner than two weeks after completion of antibiotic treatment.
    • Chronic carriers (positive stool samples after 6 months): give prolonged course of ciprofloxacin (750 bd orally for 1 month) and perform abdominal ultrasound; cholecystectomy may be necessary if gallstones are present and prolonged antibiotic treatment fails.

  • Public health measures: education on good personal and food hygiene.
  • Vaccination for travellers: (see section on travel vaccination in Appendix 3).
  • Follow up stool examinations recommended for all cases and mandatory for food handlers.
  • Food handlers require further stool examination (three consecutive daily stool samples) at three and six months post treatment.
  • Carriers (convalescent, temporary and chronic) must not work as food handlers.


  1. Teoh YL, Goh KT, Neo KS et al. A nationwide outbreak of coconut-associated paratyphoid A fever in Singapore. Ann Acad Med Singapore 1997; 26:544-8.
  2. Parry CM, Hien TT, Dougan G et al. Typhoid fever. N Engl J Med 2002; 347: 1770-82.
  3. Slinger R, Desjardins M, McCarthy AE et al. Suboptimal clinical response to ciprofloxacin in patients with enteric fever due to Salmonella spp. with reduced fluoroquinolone susceptibility: a case series. BMC Infect Dis 2004; 20:4-36.
  4. Effa EE, Bukirwa H. Azithromycin for treating uncomplicated typhoid and paratyphoid fever (enteric fever). Cochrane Database Syst Rev. 2008;(4):CD006083.
  5. Connor B, Schwartz E. Typhoid and paratyphoid fever in travellers. Lancet Infect Dis 2005; 5:623-8
  6. Bhan M, Bahl R, Bhatnager S. Typhoid and paratyphoid fever. Lancet 2005; 366: 749-62.
  7. Ty AU, Ang GY, Ang LW et al. Changing epidemiology of enteric fevers in Singapore. Ann Acad Med 2010;39:889-96.

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