John N Nkengasong

Centers for Disease Control and Prevention, Атланта, Michigan, United States

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Publications (182)849.53 Total impact

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    ABSTRACT: Objective: The objective of the World Health Organization (WHO)/U.S. President's Emergency Plan for AIDS Relief (PEPFAR) consultation was to discuss innovative strategies, offer guidance and develop a comprehensive policy framework for implementing quality-assured HIV-related point-of-care testing (POCT). Methods: The consultation was attended by representatives from international agencies (WHO, UNICEF, UNITAID, Clinton Health Access Initiative [CHAI]), USAID, Centers for Disease Control and Prevention [CDC]/PEPFAR Cooperative Agreement Partners, and experts from more than 25 countries including policy makers, clinicians, laboratory experts and program implementers. Main outcomes: There was strong consensus among all participants that ensuring access to quality of POCT represents one of the key challenges for the success of HIV prevention, treatment and care programs. The following four strategies were recommended: 1) implement a newly proposed concept of a sustainable quality assurance cycle that includes (a) careful planning; (b) definition of goals and targets; (c) timely implementation; (d) continuous monitoring; (e) improvements and adjustments, where necessary; and (f) a detailed evaluation; 2) the importance of supporting a cadre of workers (e.g. volunteer quality corps [Q-Corps]) with the role to ensure that the quality assurance cycle is followed and sustained; 3) implementation of the new strategy should be seen as a step-wise process, supported by development of appropriate policies and tools; and 4) joint partnership under the leadership of the Ministries of Health to ensure sustainability of implementing novel approaches. Conclusions: The outcomes of this consultation have been well received by program implementers in the field. The recommendations also laid the groundwork for developing key policy and quality documents for the implementation of HIV-related POCT.
    No preview · Article · Jan 2016 · AIDS (London, England)
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    ABSTRACT: To achieve global targets for universal treatment set forth by the Joint United Nations Programme on human immunodeficiency virus (HIV)/acquired immunodeficiency syndrome (AIDS) (UNAIDS), viral load monitoring for HIV-infected persons receiving antiretroviral therapy (ART) must become the standard of care in low- and middle-income countries (LMIC) (1). CDC and other U.S. government agencies, as part of the President's Emergency Plan for AIDS Relief, are supporting multiple countries in sub-Saharan Africa to change from the use of CD4 cell counts for monitoring of clinical response to ART to the use of viral load monitoring, which is the standard of care in developed countries. Viral load monitoring is the preferred method for immunologic monitoring because it enables earlier and more accurate detection of treatment failure before immunologic decline. This report highlights the initial successes and challenges of viral load monitoring in seven countries that have chosen to scale up viral load testing as a national monitoring strategy for patients on ART in response to World Health Organization (WHO) recommendations. Countries initiating viral load scale-up in 2014 observed increases in coverage after scale-up, and countries initiating in 2015 are anticipating similar trends. However, in six of the seven countries, viral load testing coverage in 2015 remained below target levels. Inefficient specimen transport, need for training, delays in procurement and distribution, and limited financial resources to support scale-up hindered progress. Country commitment and effective partnerships are essential to address the financial, operational, technical, and policy challenges of the rising demand for viral load monitoring.
    Full-text · Article · Nov 2015 · MMWR. Morbidity and mortality weekly report
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    ABSTRACT: A multiplex allele-specific (MAS) assay has been developed for the detection of HIV-1 subtype C drug resistance mutations (DRMs). We now optimized the MAS assay to determine subtype B DRMs in dried blood spots (DBS) collected from patients on antiretroviral therapy. The new assay accurately detected DRMs, including low-abundance mutations that were often missed by Sanger sequencing.
    No preview · Article · Nov 2015 · Journal of clinical microbiology
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    ABSTRACT: Access to point-of-care testing (POCT) improves patient care, especially in resource-limited settings where laboratory infrastructure is poor and the bulk of the population lives in rural settings. However, because of challenges in rolling out the technology and weak quality assurance measures, the promise of human immunodeficiency virus (HIV)–related POCT in resource-limited settings has not been fully exploited to improve patient care and impact public health. Because of these challenges, the Joint United Nations Programme on HIV/AIDS (UNAIDS), in partnership with other organizations, recently launched the Diagnostics Access Initiative. Expanding HIV programs, including the “test and treat” strategies and the newly established UNAIDS 90-90-90 targets, will require increased access to reliable and accurate POCT results. In this review, we examine various components that could improve access and uptake of quality-assured POC tests to ensure coverage and public health impact. These components include evaluation, policy, regulation, and innovative approaches to strengthen the quality of POCT.
    No preview · Article · Oct 2015 · Clinical Infectious Diseases
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    ABSTRACT: Background: The Alere point-of-care (POC) Pima™ CD4 analyzer allows for decentralized testing and expansion to testing antiretroviral therapy (ART) eligibility. A consortium conducted a pooled multi-data technical performance analysis of the Pima CD4. Methods: Primary data (11,803 paired observations) comprised 22 independent studies between 2009-2012 from the Caribbean, Asia, Sub-Saharan Africa, USA and Europe, using 6 laboratory-based reference technologies. Data were analyzed as categorical (including binary) and numerical (absolute) observations using a bivariate and/or univariate random effects model when appropriate. Results: At a median reference CD4 of 383 cells/μl the mean Pima CD4 bias is -23 cells/μl (average bias across all CD4 ranges is 10 % for venous and 15% for capillary testing). Sensitivity of the Pima CD4 is 93% (95% confidence interval [CI] 91.4% - 94.9%) at 350 cells/μl and 96% (CI 95.2% - 96.9%) at 500 cells/μl, with no significant difference between venous and capillary testing. Sensitivity reduced to 86% (CI 82% - 89%) at 100 cells/μl (for Cryptococcal antigen (CrAg) screening), with a significant difference between venous (88%, CI: 85% - 91%) and capillary (79%, CI: 73% - 84%) testing. Total CD4 misclassification is 2.3% cases at 100 cells/μl, 11.0% at 350 cells/μl and 9.5 % at 500 cells/μl, due to higher false positive rates which resulted in more patients identified for treatment. This increased by 1.2%, 2.8% and 1.8%, respectively, for capillary testing. There was no difference in Pima CD4 misclassification between the meta-analysis data and a population subset of HIV+ ART naïve individuals, nor in misclassification among operator cadres. The Pima CD4 was most similar to Beckman Coulter PanLeucogated CD4, Becton Dickinson FACSCalibur and FACSCount, and less similar to Partec CyFlow reference technologies. Conclusions: The Pima CD4 may be recommended using venous-derived specimens for screening (100 cells/μl) for reflex CrAg screening and for HIV ART eligibility at 350 cells/μl and 500 cells/μl thresholds using both capillary and venous derived specimens. These meta-analysis findings add to the knowledge of acceptance criteria of the Pima CD4 and future POC tests, but implementation and impact will require full costing analysis.
    Full-text · Article · Jul 2015 · BMC Medicine
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    ABSTRACT: Mean duration of recent infection (MDRI) and misclassification of long-term HIV-1 infections, as proportion false recent (PFR), are critical parameters for laboratory-based assays for estimating HIV-1 incidence. Recent review of the data by us and others indicated that MDRI of LAg-Avidity EIA estimated previously required recalibration. We present here results of recalibration efforts using >250 seroconversion panels and multiple statistical methods to ensure accuracy and consensus. A total of 2737 longitudinal specimens collected from 259 seroconverting individuals infected with diverse HIV-1 subtypes were tested with the LAg-Avidity EIA as previously described. Data were analyzed for determination of MDRI at ODn cutoffs of 1.0 to 2.0 using 7 statistical approaches and sub-analyzed by HIV-1 subtypes. In addition, 3740 specimens from individuals with infection >1 year, including 488 from patients with AIDS, were tested for PFR at varying cutoffs. Using different statistical methods, MDRI values ranged from 88-94 days at cutoff ODn = 1.0 to 177-183 days at ODn = 2.0. The MDRI values were similar by different methods suggesting coherence of different approaches. Testing for misclassification among long-term infections indicated that overall PFRs were 0.6% to 2.5% at increasing cutoffs of 1.0 to 2.0, respectively. Balancing the need for a longer MDRI and smaller PFR (<2.0%) suggests that a cutoff ODn = 1.5, corresponding to an MDRI of 130 days should be used for cross-sectional application. The MDRI varied among subtypes from 109 days (subtype A&D) to 152 days (subtype C). Based on the new data and revised analysis, we recommend an ODn cutoff = 1.5 to classify recent and long-term infections, corresponding to an MDRI of 130 days (118-142). Determination of revised parameters for estimation of HIV-1 incidence should facilitate application of the LAg-Avidity EIA for worldwide use.
    Full-text · Article · Feb 2015 · PLoS ONE
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    ABSTRACT: HIV-1 RNA viral load (VL) levels are used for monitoring disease progression and antiretroviral therapy outcomes in HIV-infected patients. To assess the performance of laboratories conducting HIV-1 VL testing in resource-limited settings, the US Centers for Disease Control and Prevention implemented a voluntary, free-of-charge, external quality assurance program using dried tube specimens (DTSs). DTS proficiency test (PT) panels consisting of 5 specimens were distributed between 2010 and 2012 at ambient temperature to participants. The results from participants (N ≥ 6) using the same assay were grouped, analyzed, and graded as acceptable within a group mean ± 3SDs. Mean proficiency scores were calculated by dividing the combined PT scores with the number of testing cycles using a linear regression model. Between 2010 and 2012, the number of participants enrolled increased from 32 in 16 countries to 114 in 44 countries. 78.2% of participants reported results using 10 different VL assays. The rates of participants reporting acceptable results were 96.6% (Abbott), 96.3% (Roche COBAS), 94.5% (Roche Amplicor), 93.0% (Biocentric), and 89.3% (NucliSENS). The overall mean proficiency scores improved over time (p = 0.024). DTSs are a good alternative specimen type to plasma specimens for VL PT programs as they do not require cold chain transportation and can be used on polymerase chain reaction (PCR)-based assays. Our data suggest that the CDC HIV-1 VL PT program using DTSs positively impacts the testing performance of the participants which might translate into better and accurate VL testing services to patients. Copyright © 2015, American Society for Microbiology. All Rights Reserved.
    Full-text · Article · Jan 2015 · Journal of Clinical Microbiology
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    ABSTRACT: The last ten years have witnessed a significant scale-up and access to antiretroviral therapy in Africa, which has improved patient quality of life and survival. One major challenge associated with increased access to antiretroviral therapy is the development of antiretroviral resistance due to inconsistent drug supply and/or poor patient adherence. We review the current state of both acquired and transmitted drug resistance in Africa over the past ten years (2001-2011) to identify drug resistance associated with the different drug regimens used on the continent and to help guide affordable strategies for drug resistance surveillance. A total of 161 references (153 articles, six reports and two conference abstracts) were reviewed. Antiretroviral resistance data was available for 40 of 53 African countries. A total of 5,541 adult patients from 99 studies in Africa were included in this analysis. The pooled prevalence of drug resistance mutations in Africa was 10.6%, and Central Africa had the highest prevalence of 54.9%. The highest prevalence of nucleoside reverse transcriptase inhibitor mutations was in the west (55.3%) and central (54.8%) areas; nonnucleoside reverse transcriptase inhibitor mutations were highest in East Africa (57.0%) and protease inhibitors mutations highest in Southern Africa (16.3%). The major nucleoside reverse transcriptase inhibitor mutation in all four African regions was M184V. Major nonnucleoside reverse transcriptase inhibitor as well as protease inhibitor mutations varied by region. The prevalence of drug resistance has remained low in several African countries although the emergence of drug resistance mutations varied across countries. Continued surveillance of antiretroviral therapy resistance remains crucial in gauging the effectiveness of country antiretroviral therapy programs and strategizing on effective and affordable strategies for successful treatment.
    No preview · Article · Nov 2014 · AIDS reviews
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    ABSTRACT: As more HIV-infected people gain access to antiretroviral therapy (ART), monitoring HIV drug resistance (HIVDR) becomes essential to combat both acquired and transmitted HIVDR. Studies have demonstrated dried blood spots (DBS) are a suitable alternative in HIVDR monitoring using DBS collected on Whatman 903 (W-903). In this study, we sought to evaluate two other commercially available filter papers, Ahlstrom 226 (A-226) and Munktell TFN (M-TFN), for HIVDR genotyping following ambient temperature storage. DBS were prepared from remnant blood specimens collected from 334 ART patients and stored at ambient temperature for a median time of 30 days. HIV-1 viral load was determined using NucliSENS EasyQ® HIV-1 v2.0 RUO test kits prior to genotyping of the protease and reverse transcriptase regions of the HIV-1 pol gene using an in-house assay. Among the DBS tested, 26 specimens had a viral load ≥1000 copies/mL in all three types of filter paper and were included in the genotyping analysis. Genotyping efficiencies were similar between DBS collected on W-903 (92.3%), A-226 (88.5%), and M-TFN (92.3%) filter papers (P = 1.00). We identified 50 DR-associated mutations in DBS collected on W-903, 33 in DBS collected on A-226, and 48 in DBS collected on M-TFN, resulting in mutation detection sensitivities of 66.0% for A-226 and 88.0% for M-TFN when compared to W-903. Our data indicate that differences among filter papers may exist at this storage condition and warrant further studies evaluating filter paper type for HIVDR monitoring.
    Full-text · Article · Oct 2014 · PLoS ONE
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    Katy Yao · Talkmore Maruta · Elizabeth T. Luman · John N. Nkengasong
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    ABSTRACT: Background: Efficient and reliable laboratory services are essential to effective and well-functioning health systems. Laboratory managers play a critical role in ensuring the quality and timeliness of these services. However, few laboratory management programmes focus on the competencies required for the daily operations of a laboratory in resource-limited settings. This report provides a detailed description of an innovative laboratory management training tool called Strengthening Laboratory Management Toward Accreditation (SLMTA) and highlights some challenges, achievements and lessons learned during the first five years of implementation (2009-2013) in developing countries. Programme: SLMTA is a competency-based programme that uses a series of short courses and work-based learning projects to effect immediate and measurable laboratory improvement, while empowering laboratory managers to implement practical quality management systems to ensure better patient care. A SLMTA training programme spans from 12 to 18 months; after each workshop, participants implement improvement projects supported by regular supervisory visits or on-site mentoring. In order to assess strengths, weaknesses and progress made by the laboratory, audits are conducted using the World Health Organization's Regional Office for Africa (WHO AFRO) Stepwise Laboratory Quality Improvement Process Towards Accreditation (SLIPTA) checklist, which is based on International Organization for Standardization (ISO) 15189 requirements. These internal audits are conducted at the beginning and end of the SLMTA training programme. Conclusion: Within five years, SLMTA had been implemented in 617 laboratories in 47 countries, transforming the laboratory landscape in developing countries. To our knowledge, SLMTA is the first programme that makes an explicit connection between the performance of specific management behaviours and routines and ISO 15189 requirements. Because of this close relationship, SLMTA is uniquely positioned to help laboratories seek accreditation to ISO 15189.
    Full-text · Article · Sep 2014
  • Elizabeth Luman · Katy Yao · John N. Nkengasong

    No preview · Article · Sep 2014
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    Elizabeth T Luman · Katy Yao · John Nkengasong

    Full-text · Article · Sep 2014
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    ABSTRACT: Fourth-generation HIV rapid tests (RTs) claim to detect both p24 antigen (Ag) and HIV antibodies (Ab) for early identification of acute infections, important for targeted prevention and reducing HIV transmission. In a nationally representative household survey in Swaziland, 18,172 adults, age 18-49 years, received home-based HIV rapid testing in 2010-2011. Of the 18,172 individuals, 5,822 (32.0%) were Ab+ by Determine HIV-1/2 Ab/Ab Combo and of those, 5,789 (99.4%) were confirmed reactive by Uni-Gold. Determine Combo identified 12 individuals as acute infections (Ag+/Ab-); however, none had detectable HIV-1 RNA and 8 of 12 remained HIV negative at 6-week follow-up visits (4 lost to follow up). All RT non-reactive samples were pooled and tested by nucleic acid amplification testing (NAAT) to identify acute infections. NAAT identified 13 (0.1%) of the 12,338 HIV antibody-negative specimens as HIV RNA positive with RNA levels ranging from 300 to >10,000,000 copies/mL. However, none of them were Ag+ on Determine Combo. Follow-up testing of 12 of the 13 NAAT-positive individuals at 6 months demonstrated 12 seroconversions (1 lost to follow-up). Therefore, the Combo test had a sensitivity of 0% (95% CI 0%-28%) and positive predictive value of 0% for the detection of acute infections. The ability of Determine 4(th) Generation Combo to detect antigen was very poor in Swaziland. Thus, Determine Combo does not add any value to the current testing algorithm; rather it adds additional costs and complexity to HIV diagnosis. The detection of acute HIV infections may need to rely on other testing strategies.
    Full-text · Article · Aug 2014 · Journal of Clinical Microbiology
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    ABSTRACT: Abstract Strong laboratory services and systems are critical for delivering timely and quality health services that are vital to reduce patient attrition in the HIV treatment and prevention cascade. However, challenges exist in ensuring effective laboratory health systems strengthening and linkages. In particular, linkages and referrals between laboratory testing and other services need to be considered in the context of an integrated health system that includes prevention, treatment, and strategic information. Key components of laboratory health systems that are essential for effective linkages include an adequate workforce, appropriate point-of-care (POC) technology, available financing, supply chain management systems, and quality systems improvement, including accreditation. In this review, we highlight weaknesses of and gaps between laboratory testing and other program services. We propose a model for strengthening these systems to ensure effective linkages of laboratory services for improved access and retention in care of HIV/AIDS patients, particularly in low- and middle-income countries.
    No preview · Article · Apr 2014 · AIDS patient care and STDs
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    ABSTRACT: A voluntary, cost-free external quality assessment (EQA) program established by the U.S. Centers for Disease Control and Prevention (CDC) was implemented to primarily monitor the performance of laboratories conducting HIV Early Infant Diagnosis (EID) from dried blood spots (DBS) in low to middle-income countries since 2006. Ten blinded DBS proficiency test (PT) specimens and 100 known HIV-positive and negative DBS specimens (to be used as internal controls) were shipped tri-annually to participating laboratories with reports for the PT specimens due within 30 days. The participant's results and summary of the performance of all participating laboratories and each diagnostic method were provided after each test cycle. Enrollment in the CDC PT program expanded progressively from 17 laboratories from 11 countries in 2006 to include 136 laboratories from 41 countries at the end of 2012. Despite external pressures to test and treat more children while expanding EID programs, mean PT test scores significantly improved over time as demonstrated by the upward trend from mid-2006 to end of 2012 (P = 0.001) and increase in the percentage of laboratories scoring 100% (P =0.003). The mean test scores plateaued over the past 10 testing cycles, ranging between 98.2 and 99.7% and discordant test results still occur, but at a rate no higher than 2.6%. Analysis of these test results suggests a positive impact of proficiency testing on the testing performance of the participating laboratories and a continuous training program and proficiency testing participation may translate into laboratories improving their testing accuracy.
    Full-text · Article · Dec 2013 · Journal of clinical microbiology
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    ABSTRACT: Detection of recent HIV infections is a prerequisite for reliable estimations of transmitted HIV drug resistance (t-HIVDR) and incidence. However, accurately identifying recent HIV infection is challenging due partially to the limitations of current serological tests. Ambiguous nucleotides are newly emerged mutations in quasispecies, and accumulate by time of viral infection. We utilized ambiguous mutations to establish a measurement for detecting recent HIV infection and monitoring early HIVDR development. Ambiguous nucleotides were extracted from HIV-1 pol-gene sequences in the datasets of recent (HIVDR threshold surveys [HIVDR-TS] in 7 countries; n=416) and established infections (1 HIVDR monitoring survey at baseline; n=271). An ambiguous mutation index of 2.04×10(-3) nts/site was detected in HIV-1 recent infections which is equivalent to the HIV-1 substitution rate (2×10(-3) nts/site/year) reported before. However, significantly higher index (14.41×10(-3) nts/site) was revealed with established infections. Using this substitution rate, 75.2% subjects in HIVDR-TS with the exception of the Vietnam dataset and 3.3% those in HIVDR-baseline were classified as recent infection within one year. We also calculated mutation scores at amino acid level at HIVDR sites based on ambiguous or fitted mutations. The overall mutation scores caused by ambiguous mutations increased (0.54×10(-2)3.48×10(-2)/DR-site) whereas those caused by fitted mutations remained stable (7.50-7.89×10(-2)/DR-site) in both recent and established infections, indicating that t-HIVDR exists in drug-naïve populations regardless of infection status in which new HIVDR continues to emerge. Our findings suggest that characterization of ambiguous mutations in HIV may serve as an additional tool to differentiate recent from established infections and to monitor HIVDR emergence.
    Full-text · Article · Oct 2013 · PLoS ONE
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    ABSTRACT: High-throughput, sensitive and cost-effective HIV drug resistance (HIVDR) detection assays are needed for large-scale monitoring of the emergence and transmission of HIVDR in resource-limited settings. Using suspension array technology, we have developed a multiplex allele-specific (MAS) assay that can simultaneously detect major HIVDR mutations at 20 loci. Forty-five allele-specific primers tagged with unique 24-base oligonucleotide at the 5' end were designed to detect wild-type and mutant alleles at the 20 loci of HIV-1 subtype-C viruses. The MAS assay was first established and optimized with three plasmid templates (C-wt, C-mut1 and C-mut2), and then evaluated using 148 plasma specimens from HIV-1 subtype-C-infected individuals. All the wild-type and mutant alleles could be unequivocally distinguished with plasmid templates, and the limits of detection were 1.56% for K219Q and K219E; 3.13% for L76V; 6.25% for K65R, K70R, L74V, L100I, K103N, K103R, Q151M, Y181C and I47V; and 12.5% for M41L, K101P, K101E, V106A, V106M, Y115F, M184V, Y188L, G190A, V32I, I47A, I84V and L90M. Analyses of 148 plasma specimens revealed that MAS assay gave 100% concordance with conventional sequencing at eight loci, and over 95% (95.21%-99.32%) concordance at the remaining 12 loci. The differences observed were mainly caused by 24 additional low-abundance alleles detected by the MAS assay. Ultra-deep sequencing analysis confirmed 15 of 16 low-abundance alleles. The multiplex, sensitive and straightforward result reporting assay represents a new efficient genotyping tool for HIVDR surveillance and monitoring.
    Full-text · Article · Aug 2013 · Journal of clinical microbiology
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    ABSTRACT: Abstract Whatman 903 filter paper is the only filter paper that has been used for HIV drug resistance (HIVDR) genotyping in resource-limited settings. In this study, we evaluated another dried blood specimen collection device, termed SampleTanker(®) (ST), for HIVDR genotyping. Blood specimens from 123 antiretroviral therapy (ART)-experienced patients were used to prepare ST whole blood and ST plasma specimens; they were then stored at ambient temperature for 2 or 4 weeks. The remaining plasma specimens were stored at -80°C and used as frozen plasma controls. Frozen plasma viral load (VL) was determined using the Roche Amplicor HIV-1 Monitor test, v.1.5 and 50 specimens with VL ≥3.00 log10 copies/ml were genotyped using the broadly sensitive genotyping assay. The medium VL for the 50 frozen plasma specimens with VL ≥3.00 log10 was 3.58 log10 copies/ml (IQR: 3.32-4.11) and 96.0% (48/50) of them were genotyped. Comparing to frozen plasma specimens, significantly lower genotyping rates were obtained from ST whole blood (48.98% and 42.85%) and ST plasma specimens (36.0% and 36.0%) stored at ambient temperature for 2 and 4 weeks, respectively (p<0.001). Nucleotide sequence identity and resistance profile analyses between the matched frozen plasma and ST whole blood or ST plasma specimens revealed high nucleotide sequence identities and concordant resistance profiles (98.1% and 99.0%, and 96.6% and 98.9%, respectively). Our results indicate that with the current design, the ST may not be the ideal dried blood specimen collection device for HIVDR monitoring for ART patients in resource-limited settings.
    Full-text · Article · Aug 2013 · AIDS research and human retroviruses
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    ABSTRACT: Laboratory systems worldwide are challenged not only by the need to compete for scarce resources with other sections of national health care programmes, but also with the lack of understanding of the critical role that laboratories play in the accurate diagnosis and monitoring of patients suffering from high-burdens of disease. An effective approach to establishing cost-effective laboratory systems that provide rapid and accurate test results for optimal impact on patient care is to move away from disease-specific programmes and establish integrated laboratory services. An integrated laboratory network provides all primary diagnostic services needed for care and treatment without requiring patients to go to different laboratory facilities for specific tests. Such a network focuses on providing quality-assured basic laboratory testing through the use of common specimen collection, reporting and diagnostic platforms that can be used across diseases. An integrated laboratory system also provides specimen transport to specialised laboratories and an environment conducive to the introduction and use of new and more complex technologies that would benefit the patient population and public health systems as a whole. As such, this article described various strategies for, and practical examples of, the successful integration of laboratory services.
    Full-text · Article · Apr 2013
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    ABSTRACT: In Kenya, HIV-1 viral load monitoring is commonly performed with the Cobas Amplicor using plasma specimens. Interest is growing in transitioning to real-time PCR (RT-PCR), such as the Cobas Ampliprep/Cobas TaqMan (CAP/CTM), using dried blood spots (DBS). Before implementation, direct evaluation of the two assays using DBS field specimens is required. This study compares the sensitivity, specificity, negative and positive predictive values (NPV and PPV, respectively), concordance, and agreement between HIV-1 viral load measurements using plasma and DBS specimens obtained from 512 HIV-1-infected pregnant females enrolled in the Kisumu Breastfeeding Study and tested with the Cobas Amplicor and CAP/CTM assays. The sensitivity and NPV of viral load detection in DBS specimens were higher with CAP/CTM (sensitivity, 100%; 95% confidence interval [CI], 99.1 to 100.0%; NPV, 100%; 95% CI, 59.0 to 100.0%) than the Cobas Amplicor (sensitivity, 96.6%; 95% CI, 94.3 to 98.1%; NPV, 58.8%; 95% CI, 40.7 to 75.4%). The PPVs were comparable between both assays when using DBS. The specificity of viral load detection in DBS specimens was lower with CAP/CTM (77.8%; 95% CI, 40.0 to 97.2%) than that of the Cobas Amplicor (95.2%; 95% CI, 76.2 to 99.9%). Good concordance and agreement were observed when paired plasma and DBS specimens were tested with both assays. Lower specificity with the CAP/CTM is likely due to proviral HIV-1 DNA amplification and lower detection limits with RT-PCR. However, the CAP/CTM has better sensitivity and higher throughput than the Cobas Amplicor. These findings suggest that DBS may be a suitable alternative to plasma when using RT-PCR, which could increase access to viral load monitoring in resource-limited settings.
    No preview · Article · Apr 2013 · Journal of clinical microbiology

Publication Stats

5k Citations
849.53 Total Impact Points


  • 1999-2015
    • Centers for Disease Control and Prevention
      • • Division of Global HIV/AIDS
      • • National Center for HIV/AIDS, Viral Hepatitis, STD and TB Prevention
      • • Division of HIV/AIDS Prevention, Intervention and Support
      • • Division of HIV/AIDS Prevention, Surveillance and Epidemiology
      Атланта, Michigan, United States
  • 2013
    • Kenya Medical Research Institute
      • Centre for Global Health Research
      Nairobi, Nairobi Province, Kenya
  • 1998-2005
    • Institut de Recherches Mathematiques , Cote d'Ivoire, Abidjan
      Abijan, Lagunes, Ivory Coast
    • Kenya Centers for Disease Control and Prevention
      Winam, Kisumu, Kenya
    • University of Tours
      Tours, Centre, France
  • 2004
    • Instituto de Salud Carlos III
      Madrid, Madrid, Spain
  • 1993-2002
    • Institute Of Tropical Medicine
      Antwerpen, Flemish, Belgium
  • 2000
    • National Native American AIDS Prevention Center
      Denver, Colorado, United States
  • 1993-1999
    • University of Yaoundé II
      Jaúnde, Centre, Cameroon
  • 1995
    • Max von Pettenkofer-Institut
      München, Bavaria, Germany