Trypanosoma cruzi - Chagas Disease


Indications for Testing

  • Residency in endemic area
  • Recent travel to endemic area
  • Cardiomyopathy or prototypical gastrointestinal disease without obvious etiology

Laboratory Testing 

  • CDC trypanosomiasis diagnosis 
  • Acute phase (first 60-90 days)
    • Direct detection of parasites on blood smear (Giemsa stain)
    • IgM may be useful in acute infection
  • Chronic phase (>90 days)
    • IgG confirms chronic disease – by IFA, ELISA, IHA
      • WHO recommends ≥2 tests to confirm disease
    • Cross-reactivity with Leishmania spp may occur
    • PCR requires further validation

Differential Diagnosis

Clinical Background

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


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


  • 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
  • Indeterminate phase
    • Usually asymptomatic, although symptoms of cardiomyopathy may be present
  • Chronic phase
    • May manifest decades later
    • Cardiomyopathy with arrhythmia
      • Symptoms of biventricular failure – peripheral edema, hepatomegaly
      • ~60% experience sudden cardiac death
    • Digestive system complications
      • Megacolon
      • Megaesophagus
  • Congenital disease
    • Highest risk for infection when high maternal parasitemia during acute phase
    • Prematurity, hepatosplenomegaly, meningitis/encephalitis

Indications for Laboratory Testing

  • Tests generally appear in the order most useful for common clinical situations
  • Click on number for test-specific information in the ARUP Laboratory Test Directory
Test Name and Number Recommended Use Limitations Follow Up
Trypanosoma cruzi Antibody, IgG 0051076
Method: Semi-Quantitative Enzyme-Linked Immunosorbent Assay
Preferred test if exposure to T. cruzi is suspected and Chagas disease symptoms exist (chronic phase test)

Travel history required

If test results equivocal, repeat testing in 10-14 days

Trypanosoma cruzi Antibody, IgM 0051075
Method: Semi-Quantitative Indirect Fluorescent Antibody

Detect antibodies specific to T. cruzi in patients with congruent clinical history (acute phase test)