American trypanosomiasis (Chagas' disease) and blood banking in Mexico City: seroprevalence and its potential transfusional transmission risk.

BACKGROUND: American trypanosomiasis (Chagas' disease), an anthropozoonosis fairly common in rural Latin America, has become an urban disease due to continuous migration, intra- and internationally. Blood transfusion, the second important pathway for transmission, increases its impact. Recognition of seropositive subjects among blood donors is now recommended, and clinical and serological screening enforced. Maneuvers to inactivate or remove Trypanosoma cruzi present in collected blood are recommended. METHODS: We surveyed voluntary donors at the National Institute of Cardiology in Mexico City in search of anti-T. cruzi by indirect immunofluorescence, ELISA, and Western blot analysis. Seropositive donors were identified and tested for immunoglobulin. We used types and fractions of donated blood to extract DNA and perform the PCR technique using kinetoplast primers seeking parasite DNA in blood. RESULTS: After 3,300 donors were screened, we identified 10 seropositive subjects (0.3%). These subjects were considered as indeterminate chagasic patients, came mainly from rural areas, and had IgG (100%) and IgA (30%) antibodies against a crude extract as well as a recombinant T. cruzi antigen. Identification of parasite DNA in red cell and platelet fraction was achieved from eight blood units. CONCLUSIONS: The present data provide evidence that blood donors at an urban hospital are seropositive for T. cruzi and at least 50% of donors carry the parasite potentially able to transmit T. cruzi in their cellular blood products. Serological screening should be included in routine blood-making. It is also necessary to adopt measures to inactivate or eliminate organisms in donated blood.

Chronic chagasic cardiopathy with parasitemic state (preliminary report).

Seven patients with diagnosis of dilated myocardiopathy, who fulfilled epidemiological, clinical, and serological criteria for chronic American Trypanosomosis, were submitted to hemoculture. Parasites were isolated in two patients (29%) confirming diagnosis and indicating an infection. Antibody titers did not show any relationship with the presence or absence of parasitemia nor were clinical differences noticed. Isolated Trypanosoma cruzi parasites belonged to biodeme III.

[Detection of Trypanosoma cruzi in experimental samples by the DNA polymerase chain reaction method]. / Detección de Trypanosoma cruzi en muestras experimentales por el método de reacción en cadena de la ADN polimerasa.

Chagas' disease (American Trypanosomiasis) affects more than 20 million people in Latin America. Almost 30% of those people may develop a chronic disease, which is expressed mainly as a chronic chagasic cardiopathy (CCC). Recent studies in Mexico have shown that 40% of patients suffering dilated cardiomyopathy do have serum antibodies against Trypanosoma cruzi. It is well known the difficulties of parasitologic diagnosis of CCC, which in less extent does exist for serologic diagnosis. Here we report a diagnostic method based on a molecular approach. It is able to recognize parasite DNA, and may have a clinical application. Two oligonucleotides (KNS1 and KNS2) designed from kinetoplast minicircle DNA, were used to amplify the hypervariable region by PCR technology. The method allowed an amplification of 0.8 to 1.5 minicircle DNA molecules, which equals 1/12,000 of parasite. When tissue DNA samples from mice infected with T. cruzi were subjected to amplification, a product was obtained that was recognized by a DNA probe specific for minicircle. These results correlate with immunohistochemical studies showing tissular parasites. Molecular diagnosis of American Trypanosomiasis, could be applied in human studies.

[Detection of antibodies against Trypanosoma cruzi in blood donors]. / Detección de anticuerpos contra Trypanosoma cruzi en donadores de sangre.

American trypanosomiasis is an endemic disease in Mexico. Blood transfusion has been recognized as the second main mechanism of transmission in South American countries. There is no definitive information available for Mexico. We obtained the prevalence of IgG antibodies against Trypanosoma cruzi among 1076 blood donors at the Instituto Nacional de Cardiología "Ignacio Chávez" in Mexico City. We used an antigen freshly prepared from local isolates, and the complete and soluble antigen preparations were analyzed with the Western blot technique using sera previously characterized as reactive. Blood donors' antibodies were studied with DOT-ELISA and Western blot. All donors were asked in regard to place of birth, and blood samples were serologically tested as usual in transfusion practice. The presence of IgG antibodies to T. cruzi, confirmed with a high-specificity test, showed a prevalence of 0.28 per cent. Screening for antibodies to T. cruzi; should be included in the evaluation of blood donors in Mexico.