Trypanosoma cruzi - Chagas Disease

Chagas disease or American trypanosomiasis is caused by Trypanosoma cruzi, a protozoan transmitted by infected Triatominae insects.

Epidemiology

• Prevalence
  • Almost exclusively in immigrants from Central and South America in U.S.
  • 16-18 million individuals infected worldwide
• Transmission
  • Triatominae vector species (kissing bug)
  • Maternal transplacental transfer (congenital)
  • Blood transfusion from infected donor
  • Organ transplantation
  • Ingestion of contaminated food/water (rare)

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 insect, Triatoma gerstaeckeri, and others
    • Exposure to feces deposited on skin by infected bugs

Clinical Presentation

• Acute phase
  • Mild symptoms occur for 2 weeks to 3 months
    • Romaña sign – unilateral painless edema of palpebral and periocular tissues
  • Initial signs include malaise, fever, anorexia, rash, and edema
  • Acute myocarditis in in small percentage of cases
  • Indurated area of erythema and swelling (chagoma) may indicate parasite entry site
  • Frequently undetected at this stage
• Chronic phase
  • May manifest decades later
  • Cardiomyopathy with arrhythmia
    • ~20-30% of patients (Bern, 2015)
    • Earliest sign is conduction defects – patient usually asymptomatic
    • Symptoms of biventricular failure – peripheral edema, hepatomegaly
    • ~60% experience sudden cardiac death
  • Digestive system complications
    • Megacolon
    • Ranges from mild achalasia to megaesophagus
• Congenital disease
  • Highest risk for infection when high maternal parasitemia during acute phase
  • Prematurity, hepatosplenomegaly, meningitis/encephalitis
• Immunocompromised hosts
  • Organ transplant recipients – more severe clinical spectrum including acute myocarditis and congestive heart failure
  • Immunocompromised patient with reactivation – most common are meningoencephalitis, brain abscess, and acute myocarditis