Download or read book Pooled Testing for Hiv Screening written by Lawrence M. Wein and published by Forgotten Books. This book was released on 2018-03-06 with total page 68 pages. Available in PDF, EPUB and Kindle. Book excerpt: Excerpt from Pooled Testing for Hiv Screening: Capturing the Dilution Effect In the first years of the aids epidemic, numerous instances of aids infection caused by blood transfusion were reported to the Center for Disease Control. The incidence indi cated that the blood supply is a virtually frictionless pathway for spreading the epidemic, and the extent of the epidemic dictated that screening at the individual level should be adopted. As a consequence, all infected blood donors would be identified and a measurably safer blood supply would be attained. Nevertheless, the cost for such a screening program is substantial, and many developing countries, particularly in Africa where the epidemic is spreading rapidly, are struggling to fight the disease on limited budgets. Pooled testing is one potential way to reduce the monetary cost without compromising the accuracy of the tests. The rationale behind pooled testing is simple and intuitive: suppose we can pool the sera from ten (for example) individuals and test the pool using a single test. If the seroprevalence of hiv, which is the fraction of the population that is infected, is low enough, then there is a high probability that all ten individuals in the pool are hiv negative; in this case, we would learn from a single test what otherwise would be learned from ten individual tests. If, on the other hand, the test outcome is positive, then additional tests (either pooled or individual) would need to be carried out. However, pooled testing has a possible shortcoming, the dilution efiect: there is a serious concern that if the pool size is too large, then any hiv positive sera will be sufficiently diluted so as to become undetectable by the test. These false negatives can be extremely costly, particularly when pooled testing is employed to protect the blood supply. Moreover, infected individuals exhibiting an unusually low level of antibody concentration are less likely to be detected when screened in pools. Consequently, the sensitivity of the test can be seriously affected. (sensitivity is the probability of detecting a diseased individual, whereas specificity is the probability of detecting a healthy individual.) About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works.
Download or read book Pooled Testing for HIV Screening written by Lawrence M Wein and published by Palala Press. This book was released on 2015-09-05 with total page 70 pages. Available in PDF, EPUB and Kindle. Book excerpt: This work has been selected by scholars as being culturally important, and is part of the knowledge base of civilization as we know it. This work was reproduced from the original artifact, and remains as true to the original work as possible. Therefore, you will see the original copyright references, library stamps (as most of these works have been housed in our most important libraries around the world), and other notations in the work. This work is in the public domain in the United States of America, and possibly other nations. Within the United States, you may freely copy and distribute this work, as no entity (individual or corporate) has a copyright on the body of the work.As a reproduction of a historical artifact, this work may contain missing or blurred pages, poor pictures, errant marks, etc. Scholars believe, and we concur, that this work is important enough to be preserved, reproduced, and made generally available to the public. We appreciate your support of the preservation process, and thank you for being an important part of keeping this knowledge alive and relevant.
Download or read book Pooled Testing for Hiv Prevalence Estimation written by Stefanos Andrea Zenios and published by Forgotten Books. This book was released on 2018-03-03 with total page 44 pages. Available in PDF, EPUB and Kindle. Book excerpt: Excerpt from Pooled Testing for Hiv Prevalence Estimation: Exploiting the Dilution Effect Estimation of the prevalence of hiv is important for evaluating the current status of the aids epidemic and planning effective intervention programs. However, precise estimates are very difficult to obtain because hiv infection is not associated with any clinical symptoms. Because the interval between the infection time and the onset of the clinical symptoms of aids is very long, the total number of aids cases does not provide information on the recent incidence of hiv. Consequently, population surveys are the primary mode of hiv prevalence estimation. This method screens an unbiased population sample using an antibody test, such as elisa, and estimates the prevalence from the number of positive tests. However, even this method has its limitations. Because participants in a survey must give their prior consent, self-selection bias can occur that results in an underestimation of the prevalence (gill, Adler and Day Also, the number of-tests is frequently limited by financial constraints that adversely affect the accuracy of the estimates. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works.
Download or read book Pooled Rapid Antibody Testing as a Screening Tool for New HIV Infection written by Vu Nguyen (M.D.) and published by . This book was released on 2010 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Pooled Testing for HIV Prevalence Estimation written by Stefanos Andrea Zenios and published by . This book was released on 1995 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Screening written by Angela Dean and published by Springer Science & Business Media. This book was released on 2006-07-28 with total page 347 pages. Available in PDF, EPUB and Kindle. Book excerpt: The process of discovery in science and technology may require investigation of a large number of features, such as factors, genes or molecules. In Screening, statistically designed experiments and analyses of the resulting data sets are used to identify efficiently the few features that determine key properties of the system under study. This book brings together accounts by leading international experts that are essential reading for those working in fields such as industrial quality improvement, engineering research and development, genetic and medical screening, drug discovery, and computer simulation of manufacturing systems or economic models. Our aim is to promote cross-fertilization of ideas and methods through detailed explanations, a variety of examples and extensive references. Topics cover both physical and computer simulated experiments. They include screening methods for detecting factors that affect the value of a response or its variability, and for choosing between various different response models. Screening for disease in blood samples, for genes linked to a disease and for new compounds in the search for effective drugs are also described. Statistical techniques include Bayesian and frequentist methods of data analysis, algorithmic methods for both the design and analysis of experiments, and the construction of fractional factorial designs and orthogonal arrays. The material is accessible to graduate and research statisticians, and to engineers and chemists with a working knowledge of statistical ideas and techniques. It will be of interest to practitioners and researchers who wish to learn about useful methodologies from within their own area as well as methodologies that can be translated from one area to another.
Download or read book HIV Screening and Access to Care written by Institute of Medicine and published by National Academies Press. This book was released on 2011-01-22 with total page 96 pages. Available in PDF, EPUB and Kindle. Book excerpt: More than 200,000 people in the United States living with HIV/AIDS do not know they are infected. The Institute of Medicine's Committee on HIV Screening and Access to Care held a workshop and reviewed literature to explore barriers and facilitators to more widespread HIV testing. This book contains the committee's conclusions.
Download or read book Evaluating New Matrix Pooled Testing Methods for Detecting HIV Treatment Failure with and Without Covariate Information written by Adam Brand and published by . This book was released on 2016 with total page 83 pages. Available in PDF, EPUB and Kindle. Book excerpt: University of Washington Abstract Evaluating New Matrix Pooled Testing Methods for Detecting HIV Treatment Failure with and without Covariate Information Adam Brand Chair of the Supervisory Committee: Susanne May, Associate Professor Department of Biostatistics Antiretroviral treatment for HIV has proven to lengthen and improve patients’ lives, and greatly reduce the risk of transmission. Patients receiving antiretroviral treatment for HIV must be monitored for treatment failure, so the treatment regimen can be altered to maintain low HIV viral load levels. Monitoring/testing treated HIV patients requires resources not available to resource-limited regions most in need. It has been shown that matrix pooled testing can be efficient compared to individual testing under certain conditions however, further improvements are needed. The current best-performing matrix pooled testing method for detecting HIV treatment failure does not use covariate information. Other methods which do use covariate information have not yet been shown to outperform this method in settings with realistic, skewed viral load values. We propose new methods of matrix pooled testing, some of which use covariate information, and evaluate method performance with respect to relative efficiency, sensitivity and number of testing rounds. Based on simulation results we identify a method which incorporates covariate information and outperforms the current best-performing method in settings using realistic, skewed viral load values when we have access to a predictor(s) of virologic failure.
Download or read book Screening Donated Blood for Transfusion transmissible Infections written by World Health Organization and published by World Health Organization. This book was released on 2010 with total page 73 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Blood transfusion is a life-saving intervention that has an essential role in patient management within health care systems. All Member States of the World Health Organization (WHO) endorsed World Health Assembly resolutions WHA28.72 (1) in 1975 and WHA58.13 (2) in 2005. These commit them to the provision of adequate supplies of safe blood and blood products that are accessible to all patients who require transfusion either to save their lives or promote their continuing or improving health." --Preface.
Download or read book HIV and the Blood Supply written by Institute of Medicine and published by National Academies Press. This book was released on 1995-10-05 with total page 349 pages. Available in PDF, EPUB and Kindle. Book excerpt: During the early years of the AIDS epidemic, thousands of Americans became infected with HIV through the nation's blood supply. Because little reliable information existed at the time AIDS first began showing up in hemophiliacs and in others who had received transfusions, experts disagreed about whether blood and blood products could transmit the disease. During this period of great uncertainty, decision-making regarding the blood supply became increasingly difficult and fraught with risk. This volume provides a balanced inquiry into the blood safety controversy, which involves private sexual practices, personal tragedy for the victims of HIV/AIDS, and public confidence in America's blood services system. The book focuses on critical decisions as information about the danger to the blood supply emerged. The committee draws conclusions about what was doneâ€"and recommends what should be done to produce better outcomes in the face of future threats to blood safety. The committee frames its analysis around four critical area: Product treatmentâ€"Could effective methods for inactivating HIV in blood have been introduced sooner? Donor screening and referralâ€"including a review of screening to exlude high-risk individuals. Regulations and recall of contaminated bloodâ€"analyzing decisions by federal agencies and the private sector. Risk communicationâ€"examining whether infections could have been averted by better communication of the risks.
Download or read book Biostatistical Methods for HIV Monitoring and Prevention written by Brett S. Hanscom and published by . This book was released on 2014 with total page 156 pages. Available in PDF, EPUB and Kindle. Book excerpt: Pooled-testing methods can greatly reduce the number of tests needed to identify failures in a collection of samples. Existing methodology has focused primarily on binary tests, but there is a clear need for improved efficiency when using expensive quantitative tests, such as tests for HIV viral load in resource-limited settings. We propose a matrix-pooling method which uses the EM algorithm to identify individual samples most likely to be failures. Simulation studies show that the proposed method can improve testing efficiency by a modest amount, and dramatically reduce the total number of testing rounds needed to identify all failures. In settings where the turn-around time for testing services is significant, the EM method can substantial time savings. The EM method does not perform as well when the measurements of interest are highly skewed, as is often the case with viral load concentrations. We therefore propose a second method that accommodates situations where target quantities do not follow a normal distribution. This approach uses Markov Chain Monte Carlo (MCMC) sampling to identify the failure status of individual samples, and is highly flexible in terms of assumptions regarding the distributions of both target quantities and measurement error. This method is further extended to include covariate information. Simulation studies show that the proposed method can substantially reduce turn-around time as compared to existing group-testing methods, particularly when covariate data is available that are highly predictive of failure. The proposed method did not perform as well when applied to a series of real datasets taken from actual pooled specimens. This may be due to measurement error variances for viral load testing that are much higher than anticipated. Discordant partner studies are commonly used to quantify per-act infectivity rates for HIV. Statistical models used to estimate these rates depend on self-reported sexual activity, which is notoriously unreliable. The degree to which misreported sexual activity can affect infectivity estimates has not previously been reported. By using a basic transmission model in the context of measurement error, we show that infectivity estimates can be severely biased, and that the size and direction of bias depends on the underlying infectivity rate and on the mean number of sex acts occurring in the observation window. We show that by modifying the size of this window, in certain circumstances it is possible to avoid measurement-error bias without having to use a more sophisticated statistical model. We also show that, when misreporting is ignored, covariate parameter estimates can be biased, particularly when subgroup differences are large or when sexual frequency is heterogeneous. Recent discordant partner studies have begun collecting sexual history data from both partners. We propose a latent-variable transmission model which incorporates data from both partners, and accounts for the mis-reporting of sex acts as well as non-overlapping recall periods. Bayes-MCMC methods are used to generate parameter estimates. Simulation studies demonstrate that the proposed method can dramatically reduce measurement-error bias for per-act infectivity estimation. We then apply this method to the Partners PrEP study dataset and show that HIV infectivity may be 25% higher than would be estimated with a naive model.
Download or read book Biodesign written by Stefanos Zenios and published by Cambridge University Press. This book was released on 2010 with total page 779 pages. Available in PDF, EPUB and Kindle. Book excerpt: Recognize market opportunities, master the design process, and develop business acumen with this 'how-to' guide to medical technology innovation. Outlining a systematic, proven approach for innovation - identify, invent, implement - and integrating medical, engineering, and business challenges with real-world case studies, this book provides a practical guide for students and professionals.
Download or read book Guidelines on Hepatitis B and C Testing written by World Health Organization and published by World Health Organization. This book was released on 2017 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Testing and diagnosis of hepatitis B (HBV) and C (HCV) infection is the gateway for access to both prevention and treatment services, and is a crucial component of an effective response to the hepatitis epidemic. Early identification of persons with chronic HBV or HCV infection enables them to receive the necessary care and treatment to prevent or delay progression of liver disease. Testing also provides an opportunity to link people to interventions to reduce transmission, through counselling on risk behaviors and provision of prevention commodities (such as sterile needles and syringes) and hepatitis B vaccination. These are the first WHO guidelines on testing for chronic HBV and HCV infection and complement published guidance by WHO on the prevention, care and treatment of chronic hepatitis C and hepatitis B infection. These guidelines outline the public health approach to strengthening and expanding current testing practices for HBV and HCV, and are intended for use across age groups and populations.
Download or read book AIDS Epidemic Update written by Joint United Nations Programme on HIV/AIDS. and published by UNAIDS Office. This book was released on 2004-01-01 with total page 87 pages. Available in PDF, EPUB and Kindle. Book excerpt: This annual update reports on developments in the global HIV/AIDS epidemic and draws on the most recent data available to give global and regional estimates of its scope and human toll. This edition also includes a special section on women and AIDS. Findings for 2004 include: the total number of people living with HIV reached its highest ever level of an estimated 39.4 million, with numbers rising in every region; 4.9 million new cases during the year and an estimated 3.1 million deaths; globally, just under half of all people living with HIV are women, with the proportion continuing to rise in most regions, particularly in Eastern Europe, Asia and Latin America.
Download or read book Disease Control Priorities Third Edition Volume 6 written by King K. Holmes and published by World Bank Publications. This book was released on 2017-11-06 with total page 1027 pages. Available in PDF, EPUB and Kindle. Book excerpt: Infectious diseases are the leading cause of death globally, particularly among children and young adults. The spread of new pathogens and the threat of antimicrobial resistance pose particular challenges in combating these diseases. Major Infectious Diseases identifies feasible, cost-effective packages of interventions and strategies across delivery platforms to prevent and treat HIV/AIDS, other sexually transmitted infections, tuberculosis, malaria, adult febrile illness, viral hepatitis, and neglected tropical diseases. The volume emphasizes the need to effectively address emerging antimicrobial resistance, strengthen health systems, and increase access to care. The attainable goals are to reduce incidence, develop innovative approaches, and optimize existing tools in resource-constrained settings.
Download or read book Public Health and Human Rights written by Chris Beyrer and published by JHU Press. This book was released on 2007-09-28 with total page 520 pages. Available in PDF, EPUB and Kindle. Book excerpt: Provides critical evidenced based assessements and tools with which to investigate the role of rights abrogation in the health of populations.
Download or read book Volume 16 How to Detect and Handle Outliers written by Boris Iglewicz and published by Quality Press. This book was released on 1993-01-08 with total page 99 pages. Available in PDF, EPUB and Kindle. Book excerpt: Outliers are the key focus of this book. The authors concentrate on the practical aspects of dealing with outliers in the forms of data that arise most often in applications: single and multiple samples, linear regression, and factorial experiments. Available only as an E-Book.
