Trypanosoma cruzi

Trypanosoma cruzi

 

Chagas Disease is caused by Trypanosoma cruzi, a protozoan that is transmitted by infected Triatominae bugs.

Epidemiology

  • Prevalence
    • In US, almost exclusively in immigrants from Central and South America
    • 16-18 million individuals infected worldwide; roughly 50,000 people die each year from chronic Chagas disease
  • Transmission
    • Triatomine bugs
    • Also occurs via maternal transplacental transfer, blood  transfusion, organ transplantation and rarely from ingestion of contaminated water

Organism

  • The genus Trypanosoma contains many species of protozoans
    • Only 3 cause human disease – T. cruzi, T. brucei gambiense and T. brucei rhodesiense
    • Vector-borne from the reduviid bug, Triatoma gerstaeckeri
      • Human exposure to feces from infected bugs

Clinical Presentation

  • Acute infection
    • Mild symptoms occur for 2 weeks to 3 months
    • Initial signs include malaise, fever, anorexia, rash and edema
    • Most recognized marker is Romaña sign (unilateral painless edema of palpebral and periocular tissues)
    • An indurated area of erythema and swelling (chagoma) may indicate the site of entry into the body
  • Chronic infection may manifest decades later
    • Cardiomyopathy
    • Digestive system complications
      • Megacolon
      • Megaesophagus

Diagnosis

  • Indications for testing
    • Endemic area of residency
    • Recent travel exposure
    • Development of cardiomyopathy or gastrointestinal disease without obvious etiology
  • Acute phase (first 60-90 days)
    • Direct detection of parasites on blood smear
    • IgM useful in acute infection
  • Chronic phase (>90 days)
    • IgG confirms chronic disease