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.
- 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)
- Erythematous rash- the "rose spots exanthem"
- Relative bradycardia (apparently, "a useful clue")
- A bronchitic cough is frequently present in early disease
Characteristic laboratory findings
- Leukopenia or leucocytosis
- Deranged LFTs
- Intestinal perforation -classically, the ileum perforates around the third week of illness
- Vasodilated shock
- GI haemorrhage
- Hepatic and septic encephalopathy
- Neuropsychiatric manifestations
- Septic arthritis
- 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
- 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).