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Diagnosis of Chagas disease (infection with Trypanosoma cruzi)
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.
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.
No significant cautionary statements
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