Myocardial parasite persistence in chronic chagasic patients.

Abstract

Abstract. The persistence of Trypanosoma cruzi tissue forms was detected in the myocardium of seropositive individuals clinically diagnosed as chronic chagasic patients following endomyocardial biopsies (EMBs) processed by immunohistochemical (peroxidase-anti-peroxidase [PAP] staining) and molecular (polymerase chain reaction [PCR]) techniques. An indirect immunofluorescent technique revealed antigenic deposits in the cardiac tissue in 24 (88.9%) of 27 patients. Persistent T. cruzi amastigotes were detected by PAP staining in the myocardium of 22 (84.6%) of 26 patients. This finding was confirmed with a PCR assay specific for T. cruzi in 21 (91.3%) of 23 biopsy specimens from the same patients. Statistical analysis revealed substantial agreement between PCR and PAP techniques (k ϭ 0.68) and the PCR and any serologic test (k ϭ 0.77). The histopathologic study of EMB specimens from these patients revealed necrosis, inflammatory infiltrates, and fibrosis, and made it possible to detect heart abnormalities not detected by electrocardiogram and/or cineventriculogram. These indications of myocarditis were supported by the detection of T. cruzi amastigotes by the PAP technique or its genome by PCR. They suggest that although the number of parasites is low in patients with chronic Chagas' disease, their potential for heart damage may be comparable with those present during the acute phase. The urgent necessity for testing new drugs with long-term effects on T. cruzi is discussed in the context of the present results.

Trypanosoma cruzi persistence at oral inflammatory foci in chronic chagasic patients

“…Indeed, the fact that 7 of 31 (22.6%) gum biopsy specimens from selected unquestionable CCP showing different degree of gingivitis revealed the presence of specific T. cruzi-DNA appears to suggest that the persistence of the parasite in such inflammatory foci may be a relatively frequent event. This statement, supported by the present data, seems to corroborate previous results in which the persistence of T. cruzi infection was confirmed by PCR in 91% endomyocardial biopsy specimens performed under CCP (Añez et al, 1999). Similarly, studies carried out in murine models have served to demonstrate a correlation between the persistence of T. cruzi and disease manifestation in tissues other than the heart .…”

“…This statement is supported by previous reports from experimental hosts or natural infected individuals (Tarleton et al, 1997;Olivares-Villagomez et al, 1998). The finding of persistent myocardial T. cruzi forms in CCP has been correlated with the presence and degree of inflammatory lesions which tend to be diffuse and progressive (Almeida et al, 1984;Tavares-Neto, 1990;Jones et al, 1993;Añez et al, 1999). In addition, identification of T. cruzi tissue forms in organs other than the heart from individuals who had suffered myocarditis has been associated with discrete inflammatory foci.…”

“…Whatever the mechanism allowing the parasite persistence in the inflamed gums in CCP, it may be considered as one of the reasons to explain the low parasitemia detected when serial hemoculture or xenodiagnosis are applied to confirm diagnosis in chronic individuals. The cycle transformation of the amastigote from the small foci at the gums into trypomastigote forms and its intermittent discharge into the circulating blood may explain the infrequent finding of little amount of circulating parasites, a mechanism previously suggested for the T. cruzi tissue forms persisting in the heart and other organs (Añez et al, 1999;Tarleton, 2001). In addition, the same argument may serve to explain the constant high anti-T. cruzi IgG level found in sera of CCP, which should likely be due to the persistent stimuli produced for the discharged T. cruzi trypomastigote blood forms coming from the small foci made up at the inflamed gums.…”

“…To detect seropositivity by circulating anti-T. cruzi antibodies three serologic tests were used. These were the same used in previous diagnosis and/or patient follow up, and included a direct agglutination test (DAT), an indirect immunofluorescence antibody test (IFAT), both for polyvalent and specific IgM/IgG subtypes, and an enzyme-linked immunosorbent assay (ELISA), following the conditions and procedures previously described (Añez et al, 1999).…”

“…The persistence of Trypanosoma cruzi tissue form in chronic chagasic patients (CCP) seems to be a common event in the behavior of this organism judging for the detection of the parasite itself, or parts of its genome, in treated and/or untreated long-term infected people (Añez et al, 1999;Britto et al, 2001). This statement is supported by previous reports from experimental hosts or natural infected individuals (Tarleton et al, 1997;Olivares-Villagomez et al, 1998).…”