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Organism

Salmonella typhi

Incubation: 10-21 days

Transmission

Through food or water contaminated by faeces or urine of carrier

Epidemiology

Highest incidence ages 5-19

1% become chronic carriers

Pathogenesis

Causes a systemic septicaemia (also known as Enteric fever)

If organisms escape destruction by gastric acid they can penetrate small bowel and be taken up by mesenteric lymphatics. Then it may enter the bloodstream via the thoracic duct and disseminate to organs

Salmonelli typhi:

  • Can survive and multiple inside macrophages
  • Eventual release back to blood (corresponds with symptom onset
  • Secondary bowel invasion from infected bile
  • Macrophages collect in large numbers
    • In the ileum (= peyers patches)
    • In other organs (=typhoid nodules)

It follows that disorders resulting in decreased gastric acid have increased risk of developing infection. 

Clinical features and Complications

Typhoid clinical features and complications

Typhoid clinical features and complications

Diagnosis

  • WCC normal/leukopenia (except with perforation)
  • Patients may haemolyse
  • BC positive (80%n in first week)
  • Stool cultures

Treatment

  • Fluid and electrolyte balance
  • Chloramphenicol or amoxicillin/cotrimoxazole
  • Steroids
  • Surgery is required for perforations

Prevention

  • Sanitation and hygiene
  • Vaccine is available- between 50% to 80% protective – recommended for travellers to endemic areas.

References

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