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Window Period (window + period)
Selected AbstractsImproving blood donor screening by nucleic acid technology (NAT)ISBT SCIENCE SERIES: THE INTERNATIONAL JOURNAL OF INTRACELLULAR TRANSPORT, Issue n1 2010M. Schmidt The description of the ABO blood group system by Landsteiner and coworkers marked a sea change in making blood transfusions feasible and safe for a broad range of indications. Nevertheless, with an increase in blood transfusions, side-effects such as transfusion-transmitted infections (TTIs) became more and more important. A major challenge in transfusion medicine was (and is) to develop screening assays with maximum analytical sensitivity and analytical specificity to reduce the diagnostic window period as much as possible. Until the late 1990s, blood screening for TTIs depended entirely on serological assays. Except for HBV, where the virus can be detected using HBs-antigen assays, tests for the detection of other TTIs relied almost exclusively on antibody detection. These tests, however, are associated with a relatively long diagnostic window period because they detect the response of the immune system to an infection. [source] Seroprevalence, risk factors, and hepatitis C virus genotypes in groups with high-risk sexual behavior in CroatiaJOURNAL OF MEDICAL VIROLOGY, Issue 8 2009Tatjana Vilibic Cavlek Abstract The seroprevalence, risk factors and genotypes of hepatitis C virus (HCV) in groups with high-risk sexual behavior (persons with multiple sexual partners, men who have sex with men, commercial sex workers and their clients and persons with sexually transmitted diseases) in seven Croatian cities were analyzed. A total of 821 participants without history of injecting drug use were included in the study. Anti-HCV prevalence among risk groups varied from 2.9% to 8.5% with an overall prevalence of 4.6% (95% CI,=,3.2,6.1) compared with 0.5% (95% CI,=,0.0,1.5) in controls (pregnant females; OR,=,9.66; 95% CI,=,1.32,70.7). HCV-RNA was detected in 73.1% anti-HCV positive patients. Three of the seronegative cases (2.1%) were also found to be HCV-RNA positive ("window period"). Genotype 1 was most commonly detected (55.6%). The most prevalent subtypes were 1a (38.9%) and 3a (38.9%). Sociodemographic characteristics (age, gender, marital status and level of education) were not associated with anti-HCV seropositivity. Among sexually transmitted disease markers, a higher seroprevalence of HCV infection was found in subjects with a history of HBV infection (10.5% vs. 3.8%, P,=,0.002) and gonorrhea (13.2% vs. 4.2%, P,=,0.011). No other factors reflecting risk sexual behavior such as sexual orientation, number of sexual partners and number of risk behaviors were associated with HCV seroprevalence. J. Med. Virol. 81:1348,1353, 2009. © 2009 Wiley-Liss, Inc. [source] HIV antigen,antibody combination enzyme immunoassay,the experience of a London Teaching HospitalJOURNAL OF MEDICAL VIROLOGY, Issue S1 2007Simon Goldenberg Abstract The introduction of the fourth generation HIV antigen,antibody combination enzyme immunoassay (HIV Ag,Ab EIA) has led to a reduction in the diagnostic "window period" when HIV antibody is negative during primary infection. This facilitates earlier laboratory diagnosis during sero-conversion. An HIV Ag,Ab EIA (AxSYM, Abbott Laboratories, Kent, UK) was introduced to a London Teaching Hospital since 2004 as the primary screening test. Confirmation was performed using another HIV Ag,Ab EIA (Vironostika, BioMérieux, Hampshire, UK) and an HIV Ab only assay (Bispot, Orgenics, Yavne, Israel). Retrospective analysis identified a total of 20 sero-converting patients who would have been missed if the standard antibody-only HIV tests had been used as the primary screening test. This accounted for approximately 3% of the new diagnoses made by the laboratory. The median time from onset of illness to sero-conversion was 18 days. Two patients had multiple samples analyzed between initial presentation and eventual sero-conversion. One had a prolonged sero-conversion illness lasting for over 137 days; the other sero-converted within 17 days. A plotting of the signal to cut-off ratio with time of the two HIV Ag,Ab EIAs showed a V-shaped curve and both tests were below cut-off at some time-points during sero-conversion. These two cases highlighted the difficulties in diagnosing HIV infection during sero-conversion. On the basis of these results, it is recommended that a fourth generation HIV Ag,Ab EIA could be considered for use as the standard of care, particularly in any population with a high rate of HIV infection. J. Med. Virol. 79:S23,S26, 2007. © 2007 Wiley-Liss, Inc. [source] Provider Utilization of High-Risk Donor Organs and Nucleic Acid Testing: Results of Two National SurveysAMERICAN JOURNAL OF TRANSPLANTATION, Issue 5 2009L. M. Kucirka Fears of infectious transmission from CDC high-risk donors (HRDs) remain a significant disincentive, and the potential for human immunodeficiency virus/hepatitis C virus (HIV/HCV) nucleic acid testing (NAT) to allay these fears remains unstudied. We hypothesized that NAT, which narrows the window period between infection and detectability compared to the standard ELISA, might lead to increased provider willingness to use HRDs. Between January and April 2008, we performed two national surveys: one of current NAT practice among organ procurement organizations (OPOs); a second of HRD use among transplant surgeons. Surgeons who reported accepting 10% or more offers for a given HRD behavior and organ type were classified as ,high utilizers' of that subgroup. We built hierarchical models to examine associations between OPO NAT performance and provider utilization. Providers who ranked medical risks of HIV or HCV as important disincentives to HRD use had significantly lower odds of being high utilizers (HIV odds ratio 0.22, HCV odds ratio 0.41, p < 0.005). Furthermore, both HIV and HCV NAT performance were associated with significantly higher odds of being high utilizers (HIV odds ratio 1.58, HCV 2.69, p < 0.005). The demonstrated associations between OPO NAT performance and high provider utilization of HRDs should be considered in the ongoing debate about NAT in transplantation. [source] Incremental detection of HIV infections by the HIV antigen/antibody combination assays: An Australian experience,JOURNAL OF MEDICAL VIROLOGY, Issue S1 2007Philip Cunningham Abstract Detection of acute cases of human immunodeficiency virus (HIV) infection by the direct detection of HIV antigen or HIV nucleic acid assays is well known with an estimated 5,9 days reduction in the pre-seroconversion ,window period' by the detection of HIV specific antibodies. The aim of this study was to observe the impact following routine introduction of a screening assay which simultaneously detects HIV (type 1 & 2) antigen and antibody on the yield of acute HIV infection in multiple sites servicing different patient populations with a varying range of risk factors associated with HIV acquisition. During the first year (2003,2004), a total of 27 cases of acute HIV-1 infection were identified by the HIV-1/2 Ab/Ag combo test which were confirmed to be detectable for HIV antigen only that may have gone undetected should an HIV-1/2 antibody only assay have been used. Specimens referred from higher HIV case load centers were more likely to have provided relevant clinical information consistent with acute retroviral syndrome and relevant history of risk however there were numerous cases where no clinical information was provided. This study shows that routine introduction of HIV-1/2 antigen/antibody screening assays increases the identification of acute cases of HIV infection in low prevalence setting and may represent an important tool for enhanced surveillance of incident HIV infection and opportunities for prevention. J. Med. Virol. 79:S16,S22, 2007. © 2007 Wiley-Liss, Inc. [source] | ||||||||||