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FeedbackChagas disease or American trypanosomiasis is caused by Trypanosoma cruzi, a protozoan transmitted by infected Triatominae insects. Diagnosis is generally made by testing with at least two different serologic tests; IgG confirms chronic disease.
Diagnosis
Indications for Testing
- Residency in endemic area
- Recent travel to endemic area
- Cardiomyopathy or prototypical gastrointestinal disease without obvious etiology
Laboratory Testing
- Trypanosomiasis diagnosis (CDC, 2014)
- 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 indirect fluorescent antibody (IFA), enzyme-linked immunosorbent assay (ELISA), or indirect hemagglutination antibody (IHA)
- World Health Organization (WHO) recommends at least two tests to confirm disease
- Cross-reactivity with Leishmania spp may occur
- PCR requires further validation
- IgG confirms chronic disease – by indirect fluorescent antibody (IFA), enzyme-linked immunosorbent assay (ELISA), or indirect hemagglutination antibody (IHA)
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
- High-output failure
- 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
Background
Epidemiology
- Prevalence
- U.S. – almost exclusively found in immigrants from Central and South America
- Worldwide – 16-18 million individuals infected
- 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 three cause human disease – T. cruzi, T. brucei gambiense, and T. brucei rhodesiense
- Vectorborne 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
- Mild symptoms occur for 2 weeks to 3 months
- 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 that can include acute myocarditis and congestive heart failure
- Immunocompromised patient with reactivation – most common presentations are meningoencephalitis, brain abscess, and acute myocarditis
ARUP Laboratory Tests
Screen for and detect spirochetes and blood parasites, including microfilaria, Babesia, Trypanosoma, and Plasmodium species
Patient's travel history is necessary to aid in test interpretation
Method
Stain
Aid in the diagnosis of Chagas disease (T. cruzi); may be useful in acute phase of disease
Order in conjunction with blood parasite screen
Method
Semi-Quantitative Indirect Fluorescent Antibody
Aid in the diagnosis of nonacute (chronic phase) Chagas disease (T. cruzi)
If test results are equivocal, repeat testing in 10-14 days
Method
Semi-Quantitative Enzyme-Linked Immunosorbent Assay
Medical Experts
Contributor
Couturier
Associate Professor of Clinical Pathology, University of Utah
Medical Director, Parasitology/Fecal Testing, Infectious Disease Antigen Testing, Bacteriology, and Molecular Amplified Detection, ARUP Laboratories
Contributor
Slev
Associate Professor of Clinical Pathology, University of Utah
Section Chief, Immunology; Medical Director, Immunology Core Laboratory, ARUP Laboratories
References
Additional Resources
18000201
Bern C, Montgomery SP, Herwaldt BL, et al. Evaluation and treatment of chagas disease in the United States: a systematic review. JAMA. 2007; 298 (18): 2171-81.
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Bern C. Chagas' Disease. N Engl J Med. 2015; 373 (5): 456-66.
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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
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Lescure FX, Le Loup G, Freilij H, et al. Chagas disease: changes in knowledge and management. Lancet Infect Dis. 2010; 10 (8): 556-70.
PubMed
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Rassi A, Rassi A, de Rezende JMarcondes. American trypanosomiasis (Chagas disease). Infect Dis Clin North Am. 2012; 26 (2): 275-91.
PubMed
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Woodhall D, Jones JL, Cantey PT, et al. Neglected parasitic infections: what every family physician needs to know. Am Fam Physician. 2014; 89 (10): 803-11.
PubMed
Resources from the ARUP Institute for Clinical and Experimental Pathology®
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Malan AK, Avelar E, Litwin SE, et al. 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
