Multicentric evaluation of the DiaMed enzyme-linked immunosorbent assay malaria antibody test for screening of blood donors for malaria

The risk of malaria transmission by blood transfusion is critical due to extensive travel from endemic areas to non-endemic areas. An enzyme-linked immunosorbent assay (ELISA) malaria antibody test has been developed that is claimed to perform better than the immunofluorescence assay test (IFAT). The assay contains antigens to both Plasmodium falciparum and Plasmodium vivax. A multicentre study was performed to evaluate the appropriateness of replacing the IFAT by the new ELISA test. Nine French blood banks participated in this multicentre study. Two panels of samples were evaluated. The first included 4163 samples from healthy donors and was used to calculate clinical specificity of the assay. The second involved 10 995 samples either collected retrospectively or prospectively from malaria-risk donors was used to assess the comparative performance of the ELISA and IFAT. Discordant samples were further tested using an in-house IFAT and also tested for presence of Plasmodium DNA by polymerase chain reaction. The ELISA showed a clinical specificity of 99.02%. In the malaria-risk blood donors groups the retrospective group showed a concordance rate of 92.6% (k = 0.90) while the prospective group showed a concordance rate of 97% (k = 0.46). After confirming the discordant sample results by an in-house IFAT the k index increased to 0.81. None of the discordant samples was shown to contain Plasmodium DNA. The performance of the ELISA test in this study has confirmed its potential as a new screening test for use in blood banks as an alternative to the IFAT in prevention of transfusion-transmitted malaria in non-endemic countries. (authors)