O controle da transmissão transfusional

Abstract

A alta prevalência de doadores chagásicos nos bancos de sangue do Brasil (6,9%) e da América Latina (6,5%), 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% e 1,3%, 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. Palavras-chaves: Transfusão de sangue. Doença de Chagas. Transmissão transfusional. Medidas de controle. ABSTRACTThe high prevalence of chagasic blood donors in blood centers in Brazil (6.9%) and in Latin America (6.5%) 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% and 1.3%, 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. O processo migratório no sentido campo-cidade, com o início da industrialização do Brasil, a partir da década de cinquenta, promoveu a urbanização da doença e foi responsável pela alta prevalência de doadores chagásicos...

2 nd Brazilian Consensus on Chagas Disease, 2015

“…In Brazil in the 1950s, the estimated average prevalence of positive serology for T. cruzi among potential blood donors was 8.3%. This decreased to 6.9% in the 1960s and 1970s, dropping to 3.2% in the late 1980s and early 1990s (96) . A Health ministry report from January to June 1994 stated an estimated prevalence of Chagas disease through blood transfusion, by the public blood donation network to different geographic regions nd Brazilian Consensus on Chagas Disease, 2015 of the country, of 0.75% (95) .…”

“…The risk of transmission by blood transfusion is dependent on various factors: I) the presence of the parasite in the blood or blood component transfused; II) type and number of infected blood products transfused; III) immune status of the recipient; IV) quality of the clinical-epidemiological screening; V) level of coverage of the serologic screening of donors; and VI) sensitivity of serologic tests used to screen blood donation candidates (4) (23) (95) (96) .…”

“…Given that the majority of potential blood donors are aged 18-35 years-the age group with the lowest number of candidates potentially infected with T. cruzi-and that, in recent years, the obligation of clinical, epidemiological, and serologic status screening has been established in most endemic countries, the risk of transfusion transmission of Chagas disease has been largely reduced in Latin America as a whole (4) (23) (95) (96) . In Brazil in the 1950s, the estimated average prevalence of positive serology for T. cruzi among potential blood donors was 8.3%.…”

Prevalence of Chagas disease in blood donors at the Uberaba Regional Blood Center, Brazil, from 1995 to 2009

“…With step-by-step control of natural transmission, particularly by means of eradication of the vector in various endemic countries, blood transfusions became the main mechanism of dissemination of Chagas disease in these countries during the 80s and the 90s 5 . The possibility of transmission of this disease by means of blood transfusion was rumored in 1936 in Argentina 6 and confirmed in 1952 in Brazil 7 .…”

Prevalence of Serological Ineligibility Among Blood Donors of a Hemotherapy Center in Caxias Do Sul, Southern Brazil

“…In an analysis of 25,207 blood donations performed in the Hematology Unit of Hospital Universitário de Santa Maria, southern Brazil, from January 2004 to December 2007, Cogo et al 9 found that 246 (0.98%) donors presented a positive or indeterminate serology for Chagas disease. The prevalence of positive serology for Chagas disease may be explained by the higher number of individuals who had not sought other health care services yet and whose disease had not been detected before, since it is usually asymptomatic, by the high rate of migration from rural to urban areas, and by improvements in housing, educational, and health conditions 34,35 . Serological screening for hepatitis C is performed by two tests: detection of anti-HCV antibodies or combined detection of anti-HCV antibodies and HCV antigens; and detection of HCV nucleic acid 1 .…”