Chagas' disease: application of TESA-blot in inconclusive sera from a Brazilian blood bank

The procedure used for screening Trypanosoma cruzi-infected blood donors by using two serological techniques has frequently led to discordant results. The TESA-blot, a confirmatory test for Chagas' disease, was applied in a survey of inconclusive sera from a Brazilian blood bank.

Four hundred and forty-eight sera, obtained from blood donors at the HRU-Fundação Hemominas, were tested by using the TESA-blot assay, a Western blotting method. Of these 448 sera, 348 had previously been determined as inconclusive for Chagas' disease owing to discordance between the indirect immunofluorescence assay (IFA) and the enzyme-linked immunosorbent assay (ELISA).

The TESA-blot was positive for 2.87% (10/348) of the inconclusive sera, and 100% positive and negative for the sera from chagasic (n=50) and non-chagasic (n=50) donors, respectively.

Our results clearly indicate the need to improve the diagnosis of Chagas' disease in blood banks by using new confirmatory diagnostic test(s). The TESA-blot, a new test with trypomastigote fractions of the T. cruzi Y strain, has made new approaches to the confirmation of Chagas' disease possible.