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Background: HIV infection is a concern in the army troupes because of the risk behaviour of the military population. In order to allow regular access to CD4+ T cell enumeration of military personnel as well as their dependents and civilians living with HIV, the Senegalese Army AIDS program is implementing PIMATM Alere technology in urban and semi-urban military medical centres. Validation such device is therefore required prior their wide implementation. The purpose of this study was to compare CD4+ T cell count measurements between the PIMATM Alere to the BD FACSCountTM. Methodology: We selected a total of 200 subjects including 50 patients with CD4+ T-cells below 200/mm3, 50 between 200 and 350/mm3, 50 between 351 and 500/mm3, and 50 above 500/mm3. CD4+ T-cell count was performed on venous blood using the BD FASCountTM as reference method and the PIMATM Point of Care technology. The mean biases and limits of agreement between the PIMATM Alere and BD FACSCountTM were assessed with the Bland-Altman analysis, the linear regression performed using the Passing-Bablok regression analysis, and the percent similarity calculated using the Scott method. Results: Our data have shown a mean difference of 22.3 cells/mm3 [95%CI:9.1–35.5] between the BD FACSCountTM and PIMATM Alere CD4 measurements. However, the mean differences of the two methods was not significantly different to zero when CD4+ T-cell count was below 350/mm3 (P = 0.76). The Passing-Bablok regression in categorized CD4 counts has also showed concordance correlation coefficient of 0.89 for CD4+ T cell counts below 350/mm3 whilst it was 0.5 when CD4 was above 350/mm3. Conclusion: Overall, our data have shown that for low CD4 counts, the results from the PIMATM Alere provided accurate CD4+ T cell counts with a good agreement compared to the FACSCountTM. [ABSTRACT FROM AUTHOR]

Background: Serological markers are potentially useful tools for monitoring the progress of malaria control programs, but a better understanding of antibody response dynamics is necessary. The use of a magnetic bead-based immunoassay (MBA) is advantageous compared to ELISA, due to its multiplexing capacity, but limited information is available on the standardization and validation of this assay. Methods: Several parameters for multiplex testing of antibodies to Plasmodium antigens were analysed using a set of 4 antigens and 98 sera from Senegalese rural asymptomatic and urban symptomatic individuals. The 4 antigens included Plasmodium falciparum CSP and PfAMA1 peptides, recombinant P. falciparum MSP4p20 and a Plasmodium malariae CSP (PmCSP) peptide. Comparisons with ELISA were done using MSP4p20 and whole schizont extract (SE) antigens. Results: The use of fewer beads (1000 beads per well instead of 2000) and 5 µg of antigen per 106 bead were validated as lower amounts. The use of a carrier protein (BSA) was shown to be critical when using peptides and the effect of a 24 h delayed measures was evaluated (5–25% signal decrease). Analysis of Ab responses showed almost equally high levels and prevalence in all transmission settings. Clear distinctions between rural and urban malaria were noted using PmCSP and SE antigens. Conclusions: This study underlines the importance of further optimization of the MBA technique and highlights the interest of using multistage/multispecies antigens for surveillance of malaria in endemic settings. [ABSTRACT FROM AUTHOR]