Congenital infection is currently the first cause of new cases of Chagas disease in Argentina and nonendemic areas worldwide. Its diagnosis is of utmost importance to guarantee curative treatment. To improve such diagnosis, a transfer process of PCR tests to the national laboratory network has been initiated. We performed a comparative study of four PCR assays [two end-point PCR and two duplex real-time quantitative PCR (qPCR) procedures] to detect Trypanosoma cruzi DNA in blood samples. Because satellite DNA and kinetoplastid DNA qPCR methods showed the best performance and the use of two different molecular targets for confirmatory purposes has been recommended, these methods were selected to perform the transfer process and, in consequence, subjected to an analytical verification protocol based on international guidelines. The anticipated reportable range was verified between 0.25 and 10 parasite equivalents per milliliter of blood (par. eq./mL) for both qPCR methods, and the limit of detection was estimated to be 0.87 (95% CI, 0.62-1.24) and 0.43 (95% CI, 0.32-0.59) par. eq./mL for satellite DNA and kinetoplastid DNA qPCR methods, respectively. In addition, both qPCR methods showed trueness and verified precision in the highest and the lowest concentrations tested. This work provides critical knowledge of the technology transfer process planned to cover laboratories of the regional network with known installed facilities.

High levels of circulating EBV load are used as a marker of post-transplant lymphoproliferative disorders (PTLD). There is no consensus regarding the threshold level indicative of an increase in peripheral EBV DNA. The aim of the study was to clinically validate a developed EBV quantification assay for early PTLD detection. Transversal study: paired peripheral blood mononuclear cells (PBMC), plasma and oropharyngeal lymphoid tissue (OLT) from children undergoing a solid organ transplant with (n=58) and without (n=47) PTLD. Retrospective follow-up: 71 paired PBMC and plasma from recipients with (n=6) and without (n=6) PTLD history. EBV load was determined by real-time PCR. The diagnostic ability to detect all PTLD (categories 1-4), advanced PTLD (categories 2-4) or neoplastic PTLD (categories 3 and 4) was estimated by analyzing the test performance at different cut-off values or with a load variation greater than 0.5log units. The higher diagnostic performance for identifying all, advanced or neoplastic PTLD, was achieved with cut-off values of 1.08; 1.60 and 2.47log EBVgEq/10(5) PBMC or 2.30; 2.60; 4.47loggEq/10(5) OLT cells, respectively. EBV DNA detection in plasma showed high specificity but low (all categories) or high (advanced/neoplastic categories) sensitivity for PTLD identification. Diagnostic performance was greater when: (1) a load variation in PBMC or plasma was identified; (2) combining the measure of EBV load in PBMC and plasma. The best diagnostic ability to identify early PTLD stages was achieved by monitoring EBV load in PBMC and plasma simultaneously; an algorithm was proposed.

Background: Current algorithm for Congenital Chagas Disease (cCD) diagnosis is unsatisfactory due to low sensitivity of the parasitological methods. Moreover, loss to follow-up precludes final serodiagnosis after nine months of life in many cases. A duplex TaqMan qPCR kit for Trypanosoma cruzi DNA amplification was prospectively evaluated in umbilical cord (UCB) and peripheral venous blood (PVB) of infants born to CD mothers at endemic and non-endemic sites of Argentina.Methods: We enrolled and followed-up 370 infants; qPCR was compared to gold-standard cCD diagnosis following studies of diagnostic accuracy guidelines.Findings: Fourteen infants (3 •78%) had cCD. The qPCR sensitivity and specificity were higher in PVB (72 •73%, 99 •15% respectively) than in UCB (66 •67%, 96 •3%). Positive and negative predictive values were 80 and 98 •73% and 50 and 98 •11% for PVB and UCB, respectively. The Areas under the Curve (AUC) of ROC analysis for qPCR and micromethod (MM) were 0 •81 and 0 •67 in UCB and 0 •86 and 0 •68 in PVB, respectively. Parasitic loads ranged from 37 •5 to 23,709 parasite equivalents/mL. Discrete typing Unit Tc V was identified in five cCD patients and in six other cCD cases no distinction among Tc II, Tc V or Tc VI was achieved.Interpretation: This first prospective field study demonstrated that qPCR was more sensitive than MM for early cCD detection and more accurate in PVB than in UCB. Its use, as an auxiliary diagnostic tool to MM will provide more accurate records on cCD incidence.

Real-Time PCR (qPCR) testing is recommended as both a diagnostic and outcome measurement of etiological treatment in clinical practice and clinical trials of Chagas disease (CD), but no external quality assurance (EQA) program provides performance assessment of the assays in use. We implemented an EQA system to evaluate the performance of molecular biology laboratories involved in qPCR based follow-up in clinical trials of CD. An EQA program was devised for three clinical trials of CD: the E1224 (NCT01489228), a pro-drug of ravuconazole; the Sampling Study (NCT01678599), that used benznidazole, both conducted in Bolivia; and the CHAGASAZOL (NCT01162967), that tested posaconazole, conducted in Spain. Four proficiency testing panels containing negative controls and seronegative blood samples spiked with 1, 10 and 100 parasite equivalents (par. eq.)/mL of four Trypanosoma cruzi stocks, were sent from the Core Lab in Argentina to the participating laboratories located in Bolivia and Spain. Panels were analyzed simultaneously, blinded to sample allocation, at 4-month intervals. In addition, 302 random blood samples from both trials carried out in Bolivia were sent to Core Lab for retesting analysis. The analysis of proficiency testing panels gave 100% of accordance (within laboratory agreement) and concordance (between laboratory agreement) for all T. cruzi stocks at 100 par. eq./mL; whereas their values ranged from 71 to 100% and from 62 to 100% at 1 and 10 par. eq./mL, respectively, depending on the T. cruzi stock. The results obtained after twelve months of preparation confirmed the stability of blood samples in guanidine-EDTA buffer. No significant differences were found between qPCR results from Bolivian laboratory and Core Lab for retested clinical samples. This EQA program for qPCR analysis of CD patient samples may significantly contribute to ensuring the quality of laboratory data generated in clinical trials and molecular diagnostics laboratories of CD.

The performance of the assay was suitable for the required clinical application. The assay may be useful to monitor EBV infection in transplant patients, in particular in laboratories from low-income regions that cannot afford to use commercial assays.