Indications for Testing

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

Laboratory Testing 

• 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 testing requires further validation

Differential Diagnosis

• Muscular disease
  • Trichinella spiralis infection
  • Inflammatory myopathies
• Cardiomyopathy
  • High-output failure
    • Anemia
    • Beriberi
    • Paget disease
    • Hyperthyroidism
  • Acute rheumatic fever
  • Valvular disease
    • Congenital heart disease
    • Acute myocarditis
• Megaesophagus
  • Achalasia
  • Strictures
  • Esophageal cancer
• Megacolon
  • Hirschsprung disease
  • Diabetic gastroenteropathy
  • Colonic stricture
  • Systemic sclerosis
  • Amyloidosis
• Neurologic disease
  • Myotomic dystrophy
  • Parkinson disease
  • Chronic opiate ingestion
  • Severe hyperthyroidism

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

Epidemiology

• Prevalence
  • In U.S., almost exclusively in immigrants from Central and South America
  • 16-18 million individuals infected worldwide; roughly 50,000 deaths annually from chronic Chagas disease
• Transmission
  • Common Triatominae vector species (kissing bugs) for trypanosomiasis belong to the genera Triatoma, Rhodnius, and Panstrongylus
  • Maternal transplacental transfer (congenital)
  • Blood transfusion from infected donor
  • Organ transplantation
  • Ingestion of contaminated 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
  • Initial signs include malaise, fever, anorexia, rash and edema
  • Acute myocarditis in 5% of cases
  • Most recognized marker is Romaña sign – unilateral painless edema of palpebral and periocular tissues
  • Indurated area of erythema and swelling (chagoma) may indicate parasite entry site
  • Frequently undetected at this stage
• Indeterminate phase
  • Begins after acute phase
  • Usually asymptomatic, although symptoms of cardiomyopathy may be present
• Chronic phase
  • May manifest decades later (~30% of those infected)
  • Cardiomyopathy with arrhythmia
    • Symptoms of biventricular failure – peripheral edema, hepatomegaly
    • ∼60% experience sudden cardiac death
  • Digestive system complications
    • Megacolon
    • Megaesophagus
• Congenital disease
  • Highest risk with high maternal parasitemia during acute phase
  • Prematurity, hepatosplenomegaly, meningitis/encephalitis

Treatment

• Antiprotozoal therapy is effective if patient diagnosed in acute phase

Tests generally appear in the order most useful for common clinical situations

General

• Bern C, Montgomery SP, Herwaldt BL, Rassi A Jr, 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) :2171-2181.PubMed
• Brutus L, Schneider D, Postigo J, Romero M, Santalla J, Chippaux JP. Congenital Chagas disease: diagnostic and clinical aspects in an area without vectorial transmission, Bermejo, Bolivia. Acta Trop. 2008; 106 (3) :195-199.PubMed
• Dubner S, Schapachnik E, Riera AR, Valero E. Chagas disease: state-of-the-art of diagnosis and management. Cardiol J. 2008; 15 (6) :493-504.PubMed
• Fitzwater S, Calderon M, Lafuente C, Galdos-Cardenas G, Ferrufino L, Verastegui M, Gilman RH, Bern C. Polymerase chain reaction for chronic Trypanosoma cruzi infection yields higher sensitivity in blood clot than buffy coat or whole blood specimens. Am J Trop Med Hyg. 2008; 79 (5) :768-770.PubMed
• Gorlin J, Rossmann S, Robertson G, Stallone F, Hirschler N, Nguyen KA, Gilcher R, Fernandes H, Alvey S, Ajongwen P, Contestable P, Warren H. Evaluation of a new Trypanosoma cruzi antibody assay for blood donor screening. Transfusion. 2008; 48 (3) :531-540.PubMed
• Lescure FX, 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) :556-570.PubMed
• Moncayo A, Ortiz Yanine MI. An update on Chagas disease (human American trypanosomiasis). Ann Trop Med Parasitol. 2006; 100 (8) :663-677.PubMed
• Rassi A Jr, Rassi A, Marin-Neto JA. Chagas disease. Lancet. 2010; 375 (9723) :1388-1402.PubMed
• Sanchez-Sancho F, Campillo NE, Paez JA. Chagas disease: progress and new perspectives. Curr Med Chem. 2010; 17 (5) :423-452.PubMed
• Teixeira AR, Nitz N, Guimaro MC, Gomes C, Santos-Buch CA. Chagas disease. Postgrad Med J. 2006; 82 (974) :788-798.PubMed

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) :171-178.PubMed