Trypanosoma cruzi - Chagas Disease

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

  • Diagnosis
  • Background
  • Lab Tests
  • References
  • Related Topics

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
    • Polymerase chain reaction (PCR) is very sensitive when available
  • Nonacute (chronic) phase (>90 days)
    • IgG confirms chronic disease – by IFA, ELISA, IHA
      • World Health Organization (WHO) recommends ≥2 tests to confirm disease
    • Cross-reactivity with Leishmania spp may occur
    • PCR requires further validation

Differential Diagnosis


  • Prevalence
    • Almost exclusively in immigrants from Central and South America in the 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)


  • 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 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 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 maternal parasitemia is high 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
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.

Parasites Smear (Giemsa Stain), Blood 0049025
Method: Stain

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

Trypanosoma cruzi Antibody, IgG 0051076
Method: Semi-Quantitative Enzyme-Linked Immunosorbent Assay


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

General References

Bern C, Montgomery SP, Herwaldt BL, Rassi A, Marin-Neto JA, Dantas RO, Maguire JH, Acquatella H, Morillo C, Kirchhoff LV, Gilman RH, Reyes PA, Salvatella R, Moore AC. Evaluation and treatment of chagas disease in the United States: a systematic review. JAMA. 2007; 298(18): 2171-81. PubMed

Bern C. Chagas' Disease. N Engl J Med. 2015; 373(5): 456-66. PubMed

Hemmige V, Tanowitz H, Sethi A. Trypanosoma cruzi infection: a review with emphasis on cutaneous manifestations. Int J Dermatol. 2012; 51(5): 501-8. PubMed

Lescure F, Le Loup G, Freilij H, Develoux M, Paris L, Brutus L, Pialoux G. Chagas disease: changes in knowledge and management. Lancet Infect Dis. 2010; 10(8): 556-70. PubMed

Rassi A, Rassi A, de Rezende JM. American trypanosomiasis (Chagas disease). Infect Dis Clin North Am. 2012; 26(2): 275-91. PubMed

Woodhall D, Jones JL, Cantey PT, Wilkins PP, Montgomery SP. Neglected parasitic infections: what every family physician needs to know. Am Fam Physician. 2014; 89(10): 803-11. PubMed

References from the ARUP Institute for Clinical and Experimental Pathology®

Malan AK, Avelar E, Litwin SE, Hill HR, Litwin CM. Serological diagnosis of Trypanosoma cruzi: evaluation of three enzyme immunoassays and an indirect immunofluorescent assay. J Med Microbiol. 2006; 55(Pt 2): 171-8. PubMed

Medical Reviewers

Last Update: October 2017