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Blood safety has been of paramount concern worldwide over the last decades, and Latin America and Mexico are no exception. Factors of utmost importance include the use of highly efficient screening tests and the encouragement of voluntary donation. This review summarizes the current situation in Latin America and particularly in Mexico with respect to these key issues. Except for some specific regions, there is a lack of progress of voluntary donation in Mexico compared with other Latin American countries. A more efficient voluntary donation system could provide donors with lower prevalence of infectious agents such as human immunodeficiency, hepatitis B, and hepatitis C viruses. In Latin America, and specifically in countries such as Argentina, Brazil and Nicaragua, voluntary donation and blood safety are strongly encouraged. However, to date, in Mexico there has not been a specific blood safety project because of fragmentation of the health system model with structural differences among organisations. Although national policies are established to grant health coverages in Mexico, blood safety is still limited and outdated because of oversights in technical fields and regulations. Individual molecular biological tests for donor screening have recently been incorporated into the Mexican national regulations. Although the routine use of these tests as part of effective donor screening is still not compulsory, it is enabling a progressive improvement of blood safety.

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Nearly 100,000 patients are waiting for a kidney transplant, yet each year only 11,000 undergo transplantation with a deceased donor kidney. Annual death rates among waitlist registrants range from 5% to 15%; many die before receiving a transplant. Not surprisingly, registrants turn to family and friends to become living kidney donors on their behalf. Living kidney donor selection practices aim to quantify lifetime risk for kidney failure based on a candidate's predonation demographic and health characteristics. It has been established that estimated lifetime risk for kidney failure varies considerably based on predonation comorbid conditions, and as such, it is of paramount importance that potential living donor candidates undergo proper medical, surgical, and psychosocial screening before donation. This installment of AJKD's Core Curriculum in Nephrology provides readers with the tools necessary for proper evaluation of living kidney donor candidates.

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Donor-derived Strongyloides stercoralis infections in transplant recipients are a rare but recognized complication. In this case series, we report donor-derived allograft transmission of Strongyloides in three solid organ transplant recipients. Following detection of infection in heart and kidney-pancreas recipients at two different transplant centers, a third recipient from the same donor was identified and diagnosed. S. stercoralis larvae were detected in duodenal aspirates, bronchial washings, cerebrospinal fluid, urine and stool specimens. Treatment with ivermectin and albendazole was successful in two of the three patients identified. The Centers for Disease Control and Prevention was contacted and performed an epidemiologic investigation. Donor serology was strongly positive for S. stercoralis antibodies on retrospective testing while all pretransplant recipient serum was negative. There should be a high index of suspicion for parasitic infection in transplant recipients and donors from endemic regions of the world. This case series underscores the need for expanded transplant screening protocols for Strongyloides. Positive serologic or stool tests should prompt early treatment or prophylaxis in donors and recipients as well as timely notification of organ procurement organizations and transplant centers.

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Transfusion-transmitted malaria is a severe disease with high fatality rate. Most Brazilian blood banks in the Amazon region perform malaria screening using microscopic examination (thick smears). Since low parasite concentrations are expected in asymptomatic blood donors a high sensitivity test should be used for donor screening. This study determined the sensitivity of a nested-PCR for plasmodium detection in pooled samples. We performed a one-stage criterion validation study with 21 positive samples pooled with samples from ten negative volunteer until three different concentrations were reached (0.33; 0.25; 0.20 parasites/µL - p/µL). Nested PCR was performed as described by Snounou et al. (1993). Sensitivities (and confidence intervals) were determined by stratum of final parasite concentration on the pooled samples. All samples with parasitemia values of 0.33 and 0.25 p/µL had 100% sensitivity (95%CI=86.3-100). One negative result was obtained from a sample with 0.20 p/µL sensitivity=95.2% (95%CI=76.2-99.9). Compared to parasitemia detectable under ideal conditions of thick smear, this nested-PCR in pooled sample was able to detect 40 times more parasites per microliter. Nested-PCR in pooled samples should be considered as a high sensitive alternative to thick smear for donor screening in blood banks at endemic regions. Local authorities need to assess cost:benefit advantages of this method compared to alternatives.

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INTRODUCTION: Blood transfusion is an important transmission route of Trypanosoma cruzi (T cruzi), a major parasitic infection in Central and South America. The limited treatment options are most effective in acute Chagas' infection. At present, there is no current data on the prevalence of T cruzi in the blood donor population of Guyana. This information is necessary to protect the supply of the blood donation programme. This study sought to determine the prevalence of T cruzi in the blood supply at the National Blood Transfusion Services of Guyana with the hope of providing knowledge to the on-going surveillance for Chagas' disease worldwide and therefore address the risk of its spread by blood transfusion. METHODS: Two commercialized ELISAs utilizing crude or recombinant T cruzi antigens were used to study 2000 blood samples voluntarily donated for the purpose of altruistic or family replacement donation retrospectively. RESULTS: The results showed that approximately 1 in 286 donations tested positive for antibodies to T cruzi. CONCLUSION: These results indicate that T cruzi continues to be a risk in Guyana and there is a need to continue screening donated blood. Trypanosoma cruzi is a life-long infection and infected persons may be asymptomatic chronic carriers of the disease. Education, housing improvement, and controlled use of insecticides should be introduced to contain Chagas' disease.

INTRODUCCIÓN: La transfusión de Sangre es una vía de transmisión importante del Trypanosoma cruzi (T cruzi), una infección parasitaria mayor en América Central y América del Sur. Las opciones de tratamiento limitadas son más eficaces en los casos de la enfermedad de Chagas aguda. En el presente, no existen datos actualizados acerca de la prevalencia del T cruzi en la población de donantes de sangre en Guyana. Esta información es necesaria para proteger el suministro del programa de donación de sangre. Este estudio se propuso determinar la prevalencia de T cruzi en el suministro de sangre de los Servicios Nacionales de Transfusión de Sangre en Guyana, con la esperanza de aportar conocimientos a la vigilancia que tiene lugar en relación con la enfermedad de Chagas a nivel mundial, y por consiguiente aborda el riesgo de la difusión de esta última mediante la transfusión de sangre. MÉTODOS: Dos inmunoensayos ELISA con antígenos de T cruzi crudos o recombinantes, fueron utilizados a fin de estudiar 2000 muestras de sangre donadas voluntariamente a modo de donaciones altruistas o de reposición familiar, retrospectivamente. RESULTADOS: Los resultados mostraron que aproximadamente 1 de 286 donaciones daban positivo a anticuerpos frente al T cruzi. CONCLUSIÓN: Estos resultados indican que el T cruzi sigue siendo un riesgo en Guyana, y hay necesidad de continuar tamizando la sangre donada. El Trypanosoma cruzi es una infección crónica, y las personas infectadas pueden ser portadores asintomáticos crónicos de la enfermedad. Deben introducirse medidas en cuanto a educación, mejoramiento de las viviendas, y uso controlado de insecticidas, a fin de detener la enfermedad de Chagas.

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Classical serological screening assays for Chagas' disease are time consuming and subjective. The objective of the present work is to evaluate the enzyme immuno-assay (ELISA) methodology and to propose an algorithm for blood banks to be applied to Chagas' disease. Seven thousand, nine hundred and ninety nine blood donor samples were screened by both reverse passive hemagglutination (RPHA) and indirect immunofluorescence assay (IFA). Samples reactive on RPHA and/or IFA were submitted to supplementary RPHA, IFA and complement fixation (CFA) tests. This strategy allowed us to create a panel of 60 samples to evaluate the ELISA methodology from 3 different manufacturers. The sensitivity of the screening by IFA and the 3 different ELISA's was 100%. The specificity was better on ELISA methodology. For Chagas disease, ELISA seems to be the best test for blood donor screening, because it showed high sensitivity and specificity, it is not subjective and can be automated. Therefore, it was possible to propose an algorithm to screen samples and confirm donor results at the blood bank.

Os testes sorológicos clássicos utilizados na triagem de doadores de sangue são trabalhosos e subjetivos. O objetivo do presente trabalho é o de avaliar a metodologia imuno-enzimática (ELISA) e propor um algorítmo para doença de Chagas em bancos de sangue. Foram estudados 7999 doadores de sangue e/ou componentes cujas amostras foram testadas com o objetivo de tria-las sorologicamente para doença de Chagas utilizando hemaglutinação passiva reversa (RPHA) e imunofluorescência indireta (IFA). As amostras reativas em pelo menos uma destas metodologias, foram retestadas com reativos diferentes por RPHA, IFA e fixação de complemento (CFA). Esta estratégia nos permitiu criar um painel de 60 amostras com as quais tornou-se possível a avaliação do método imunoenzimático (ELISA). A sensibilidade da triagem dos doadores pelos métodos ELISA e IFA foi de 100%. A especificidade foi melhor para a metodologia imunoenzimática. O teste ELISA parece ser o ideal para triagem em bancos de sangue pois é altamente sensível, específico, não é subjetivo e pode ser automatizado. Desta forma, torna-se possível a formulação de um algorítimo a ser utilizado na triagem sorológica e confirmação de resultados em doadores de bancos de sangue.

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