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.

Elimination of Chagas disease transmission: perspectives

One hundred years after its discovery by Carlos Chagas, American trypanosomiasis, or Chagas disease, remains an epidemiologic challenge. Neither a vaccine nor an ideal specific treatment is available for most chronic cases. Therefore, the current strategy for countering Chagas disease consists of preventive actions against the vector and transfusion-transmitted disease. Here, the present challenges, including congenital and oral transmission of Trypanosoma cruzi infections, as well as the future potential for Chagas disease elimination are discussed in light of the current epidemiological picture. Finally, a list of challenging open questions is presented about Chagas disease control, patient management, programme planning and priority definitions faced by researchers and politicians.