Evaluation of cross reactivity between Trypanosoma cruzi and Leishmania infantum in serologically ineligible blood donors due to chagas diseas

Inconclusive serological screening for Trypanosoma cruzi has been a problem for blood banks. This study examined the performance of serological techniques for Chagas disease in reagent samples from blood bank screenings and verified the possibilities of cross reactivity with visceral leishmaniasis. 68 samples of reagent donors tested with ELISA for Chagas disease were evaluated by other techniques and for the detection of anti-Leishmania antibodies. Four donors (5.9%) with positive results for T. cruzi were positive for ELISA Kalazar Detect (visceral leishmaniasis),three of which were confirmed by Western blot. This study confirms the specificity of the tests for Chagas disease in blood banks and reinforces the urgent adoption of measures to assess the real risk of transfusion transmission of visceral leishmaniasis

Length and caliber of the rectosigmoid colon among patients with Chagas disease and controls from areas at different altitudes

Introduction In this study, we investigated radiological changes in the sigmoid colon in chagasic patients by comparing their colon lengths and caliber with those of non-chagasic living in the same region and non-chagasic living at high altitudes. Methods A total of 317 individuals were evaluated using clinical, serological and radiological methods and divided into three groups: 1) one hundred and nine non-chagasic individuals from Uberaba, Brazil; 2) sixty-one non-chagasic from Puno, Peru; 3) one hundred forty-seven chagasics examined in Uberaba, being 62 without megacolon (3A), 72 with megacolon (3B) and 13 with doubtful diagnosis of megacolon (3C). Results In group 2, the sigmoid colon had a significantly larger caliber (p=0.001) and the rectosigmoid colon was longer (p<0.001) than group 1. In subgroup 3A, the sigmoid colon (p<0.001) and rectum (p<0.001) had a significantly larger caliber and the rectosigmoid was longer (p<0.001) than that of the non-chagasic individuals. In subgroup 3B, the rectosigmoid was longer in all patients, and the caliber of the sigmoid was significantly larger than that of subjects in subgroups 3A and 3C (p<0.001). Conclusions Morphometric analysis confirms that Chagas disease may increase the caliber and length of the rectosigmoid. Our results suggest that altitude, ethnicity and diet may have influenced the size and length of the rectosigmoid of andean patients. .

Performance of six diagnostic tests to screen for Chagas disease in blood banks and prevalence of Trypanosoma cruzi infection among donors with inconclusive serology screening based on the analysis of epidemiological variables

OBJECTIVE: The frequent occurrence of inconclusive serology in blood banks and the absence of a gold standard test for Chagas'disease led us to examine the efficacy of the blood culture test and five commercial tests (ELISA, IIF, HAI, c-ELISA, rec-ELISA) used in screening blood donors for Chagas disease, as well as to investigate the prevalence of Trypanosoma cruzi infection among donors with inconclusive serology screening in respect to some epidemiological variables. METHODS: To obtain estimates of interest we considered a Bayesian latent class model with inclusion of covariates from the logit link. RESULTS: A better performance was observed with some categories of epidemiological variables. In addition, all pairs of tests (excluding the blood culture test) presented as good alternatives for both screening (sensitivity > 99.96% in parallel testing) and for confirmation (specificity > 99.93% in serial testing) of Chagas disease. The prevalence of 13.30% observed in the stratum of donors with inconclusive serology, means that probably most of these are non-reactive serology. In addition, depending on the level of specific epidemiological variables, the absence of infection can be predicted with a probability of 100% in this group from the pairs of tests using parallel testing. CONCLUSION: The epidemiological variables can lead to improved test results and thus assist in the clarification of inconclusive serology screening results. Moreover, all combinations of pairs using the five commercial tests are good alternatives to confirm results.

O controle da transmissão transfusional / Control of transfusional transmission

A alta prevalência de doadores chagásicos nos bancos de sangue do Brasil (6,9 por cento) e da América Latina (6,5 por cento), nas décadas de 60 e 70, aliada ao combate ao vetor a partir dos anos setenta, fez com que a doença de Chagas transfusional, a partir da década de oitenta, se tornasse o principal mecanismo de transmissão da doença na maioria dos países endêmicos. Contudo, os resultados altamente favoráveis do combate ao vetor e da cobertura sorológica dos doadores, reduziu a prevalência de soropositividade para 0,2 por cento e 1,3 por cento, respectivamente, no Brasil e América Latina e o índice de transmissão anual, via transfusão de sangue no Brasil, de 20.000 para 13 em quatro décadas. Entretanto, paralelamente aos grandes avanços obtidos pelos países endêmicos, a doença de Chagas alcançou, via processo migratório, os países não endêmicos da América do Norte e da Europa, além do Japão e Austrália, colocando em risco os receptores de sangue destes países e transformando a doença de Chagas num problema de saúde global. A segurança transfusional, propiciada pela triagem sorológica, trouxe, porém outro importante problema, qual seja, a alta proporção de reações inconclusivas e dois grandes desafios: o significado de tais exames e que orientação proporcionar ao doador. Contudo, as estratégias adotadas pelos países não endêmicos e os avanços alcançados pelos endêmicos, prenunciam o breve, auspicioso e intensamente sonhado controle vetorial e transfusional da doença de Chagas.

The high prevalence of chagasic blood donors in blood centers in Brazil (6.9 percent) and in Latin America (6.5 percent) in the 60's and 70's, together with the combat to the vector since the 70's have made transfusion Chagas disease the main mechanism of the disease transmission in the 80's. However, the highly favorable results achieved to eliminate the vector and the serologic screening of blood donors, reduced the prevalence of serum positivity to 0.2 percent and 1.3 percent, respectively and the rate of annual transmission through blood transfusion from 20.000 to 13 in four decades in Brazil. Nevertheless, despite outstanding advancements in endemic countries, Chagas disease reached, via migration, non-endemic countries in North America and Europe besides Japan and Australia, placing their blood recipients at risk and turning Chagas disease into a worldwide health problem. Transfusion safety through serologic selection raised another big issue i.e. high proportion of inconclusive reactions as well as two great challenges: the meaning of such exams and what guidelines to provide the donor. However, the strategies adopted by non-endemic countries and the advancements achieved by endemics so far forecast the highly wished vector and transfusion control of Chagas disease.