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Myocardial parasite persistence in chronic chagasic patients
1Facultad de Ciencias, Instituto de Cardiologia, Universidad de Los Andes, Mérida, Venezuela.
Summary
Persistent Trypanosoma cruzi (T. cruzi) infections were found in the heart muscle of chronic Chagas disease patients. These tissue-bound parasites, detected by PCR and PAP staining, indicate ongoing myocarditis and potential for significant heart damage.
Area of Science:
- Infectious Diseases
- Cardiology
- Molecular Biology
Background:
- Chagas disease, caused by Trypanosoma cruzi, often leads to chronic cardiac complications.
- The persistence of T. cruzi in cardiac tissue is a key factor in the development of chronic chagasic cardiomyopathy.
- Detecting low-level parasite presence in chronic cases is crucial for understanding disease progression.
Purpose of the Study:
- To detect persistent Trypanosoma cruzi tissue forms in the myocardium of chronic Chagasic patients.
- To evaluate the efficacy of immunohistochemical (peroxidase-anti-peroxidase [PAP] staining) and molecular (polymerase chain reaction [PCR]) techniques in identifying T. cruzi in endomyocardial biopsies (EMBs).
- To correlate parasite detection with histopathological findings and cardiac abnormalities.
Main Methods:
- Endomyocardial biopsies (EMBs) were obtained from clinically diagnosed chronic Chagasic patients.
- Immunohistochemical (peroxidase-anti-peroxidase [PAP] staining) and molecular (PCR) techniques were used to detect T. cruzi.
- Indirect immunofluorescence was employed to detect antigenic deposits in cardiac tissue.
- Histopathological analysis of EMBs was performed to identify signs of myocarditis.
Main Results:
- Persistent T. cruzi amastigotes were detected in the myocardium of a high percentage of patients using both PAP staining (84.6%) and PCR (91.3%).
- Antigenic deposits were found in 88.9% of patients via indirect immunofluorescence.
- Histopathology revealed necrosis, inflammation, and fibrosis, with some abnormalities not detected by conventional imaging.
- Strong agreement was observed between PCR and PAP techniques (k=0.68) and PCR and serologic tests (k=0.77).
Conclusions:
- Trypanosoma cruzi persists in the myocardium of chronic Chagasic patients, even at low levels.
- PAP staining and PCR are effective methods for detecting T. cruzi in EMBs, confirming active myocarditis.
- The presence of parasites, even in low numbers, contributes to cardiac damage comparable to the acute phase, highlighting the need for new long-term treatments.