External quality control program in screening for infectious diseases at blood banks in Mexico

Quality control for the detection of infectious markers in blood banks is a necessary activity to ensure the accuracy of donor screening results. Considering that in Mexico blood safety is one of the goals of the National Action Programs, it is essential to evaluate banks through an External Quality Control Program.

To analyze one of the evaluations that showed the greatest participation (2014-2/lot46) of banks in the Mexican Republic in the detection of transfusion-transmitted diseases.

A randomized panel of infectious markers of HIV, HCV, HBV, Treponema pallidum and Trypanosoma cruzi was manufactured under high quality standards. The evaluation criteria for each infectious marker were the identification of false positives and false negative results. Additionally, technologies used to detect infectious markers were requested for each bank.

Of the 503 banks, only 374 participated in the evaluation. Technologies based on chemiluminescence, immunofluorescence and immunocolorimetry were used to detect viral markers. Even rapid tests for T. pallidum continue to be the methods of choice with 42%. Trypanosoma cruzi was 20% with fast techniques versus 80% with automated tests. Highest incidence of false positives was identified for T. pallidum and HBV, followed by T. cruzi, HIV and HCV. Fourteen (3.74%) false negatives results were identified for T. cruzi, followed by T. pallidum (n = 5/1.33%), HCV (n = 4/1.06) and HVB/HIV (n = 2/0.53%).

False positive results identified for each infectious marker was considered high. This evidence will allow us to focus on areas of opportunity during serologic screening with greater emphasis on good laboratory practices.