Typhoid fever is the third topic of Sivakumar and Pelly's chapter on tropical diseases in Oh's Manual. It has not been interrogated in the SAQs directly, and is an infrequent differential.

As an alternative, the 2003 WHO document on this disease offers a detailed overview.

Microbiology

  • Salmonella typhi is an anaerobic Gram-negative rod.
  • Genetically, it closely resembles E.coli
  • During an acute infection, S. typhi multiplies in mononuclear phagocytic cells before being released into the bloodstream (this is why azithromycin is such an effective agent)
  • Incubation periods ranging from 3 days to more than 60 days have been reported.

Clinical manifestations and features of history

  • Returned traveller, or a consumer of "international food"
    • Given the faeco-oral rote of transmission, inoculation may have occurred by some sort of a non-standard route.
  • Fever, chills, rigors
  • Constipation in adults is more common than diarrhoea
  • Abdominal pain (usually right lower quadrant)
  • Hepatosplenomegaly
  • Erythematous rash- the "rose spots exanthem"
  • Relative bradycardia (apparently, "a useful clue")
  • A bronchitic cough is frequently present in early disease

Characteristic laboratory findings

  • Anaemia
  • Leukopenia or leucocytosis
  • Deranged LFTs

Critical complications

  • Intestinal perforation -classically, the ileum perforates around the third week of illness
  • Vasodilated shock
  • GI haemorrhage
  • Jaundice
  • Hepatic and septic encephalopathy
  • Neuropsychiatric manifestations
  • Septic arthritis
  • Pericarditis

Diagnostic approach

  • Blood cultures are usually positive in severe cases
  • Clinical illness is usually accompanied by a sustained bacteraemia
  • The volue of cultured blood is the most important determinant of success
  • Bone marrow culture is the most sensitive
  • Stool culture may be helpful, but does not discriminate active disease from chronic carriers
  • IgM serology may be useful

Management

  • The Sanford Guide recomends ciprofloxacin or ceftriaxone.
  • Azithromycin is an alternative
  • A 14 day course may be required for complicated infection
  • Dexamethasone reduces mortality in severe typhoid fever (i.e. whenever any of the abovementioned "critical complications" occur).

References

Chapter 73  (pp. 743) Tropical  diseases  by Ramachandran  Sivakumar  and  Michael  E  Pelly

Kothari, V. R., D. Karnad, and Lata S. Bichile. "Tropical infections in the ICU."JOURNAL-ASSOCIATION OF PHYSICIANS OF INDIA 54.R (2006): 291.

World Health Organization. "Background document: the diagnosis, treatment and prevention of typhoid fever." (2003).

Felman, Yehudi M., and N. B. Ricciardi. "Sexually transmitted enteric diseases." Bulletin of the New York Academy of Medicine 55.6 (1979): 533.

Trivedi, N. A., and P. C. Shah. "A meta-analysis comparing the safety and efficacy of azithromycin over the alternate drugs used for treatment of uncomplicated enteric fever." Journal of postgraduate medicine 58.2 (2012): 112.