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Interpretive Handbook

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Test 86159 :
Trypanosoma cruzi Antibody, IgG, Serum

Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

Chagas disease (American trypanosomiasis) is an acute and chronic infection caused by the protozoan hemoflagellate, Trypanosoma cruzi which is endemic in many areas of South and Central America. The parasite is usually transmitted by the bite of reduviid (or "kissing") bugs of the genus Triatoma, but also has been transmitted by blood transfusion, organ transplantation, and apparently also by food ingestion. The acute febrile infection is most often undiagnosed and often resolves spontaneously. The actively motile (trypomastigote) form may be demonstrated in peripheral blood by stained smears during the acute phase. Chronic infections are often asymptomatic but may progress to produce disabling and life-threatening cardiac (cardiomegaly, conduction defects) and gastrointestinal (megaesophagus and megacolon) disease. These damaged tissues contain the intracellular (amastigote) of Trypanosoma cruzi. The parasite is not seen in the blood during the chronic phase. Diagnosis at this time is made by serology or tissue biopsy. A positive serology is considered presumptive evidence of active infection. Serologically positive asymptomatic persons are capable of transmitting the infection.

Useful For Suggests clinical disorders or settings where the test may be helpful

Diagnosis of Chagas disease (infection with Trypanosoma cruzi)

Interpretation Provides information to assist in interpretation of the test results

A positive serology is suggestive of recent infection or past exposure.  Results should be correlated with clinical presentation and other laboratory findings.

 

Infected individuals usually begin producing antibodies to Trypanosoma cruzi during the first month following exposure to the parasite. Antibody levels may fluctuate during the chronic phase of the disease and may become undetectable after several months. Uninfected individuals are not expected to have detectable levels of antibodies to Trypanosoma cruzi.

Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

No significant cautionary statements

Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.

Negative

Clinical References Provides recommendations for further in-depth reading of a clinical nature

1. Kirchhoff LV: American trypanosomiasis (Chagas' disease). In Topical Infectious Diseases. Edited by RL Guerrant, et al. Philadelphia, Churchill Livingstone, 1999, pp 785-796

2. Umezawa ES, Stolf AM, Corbett CE, Shikanai-Yasuda MA: Chagas' disease. Lancet 2001;357:797-799

3. Leiby DA, Read EJ, Lenes BA, et al: Seroepidemiology of Trypanosoma cruzi, etiologic agent of Chagas' disease, in US blood donors. J Infect Dis 1997;176:1047-1052

4. Grant IH, Gold JW, Wittner M, et al: Transfusion-associated acute Chagas' disease acquired in the United States. Ann Intern Med 1989;111:849-851


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