Detection of dengue, chikungunya, and Zika RNA in blood donors from Southeast Asia.

BACKGROUND: Chikungunya (CHIKV), dengue (DENV), and Zika (ZIKV) viruses are of concern due to the potential of transfusion transmission in blood, especially in regions such as Southeast Asia where the viruses are endemic. The recent availability of nucleic acid testing (NAT) to screen blood donations on an automated platform provides the opportunity to detect potentially infectious units in asymptomatic donors. STUDY DESIGN AND METHODS: Three thousand blood donations from Vietnam and 6000 from Thailand were screened with a real-time polymerase chain reaction (PCR) test (cobas CHIKV/DENV, Roche Diagnostics, Indianapolis, IN) and equal numbers on cobas Zika (Roche Diagnostics). Reactive samples were tested by alternative NAT with resolution of discordant results by heminested PCR. Throughput of simultaneous testing of the two assays on the cobas 8800 system (Roche Diagnostics) was evaluated. RESULTS: In Vietnam, 9 of 3045 samples were reactive for DENV and all were confirmed, for a prevalence (with 95% confidence interval [CI]) of 0.296% (0.135-0.560). In Thailand, 2 of 6000 samples were reactive for CHIKV, 4 of 6000 for DENV, and 1 of 6005 for ZIKV, and all confirmed. The prevalence of CHIKV is 0.033% (0.004-0.120), DENV 0.067% (0.018-0.171), and ZIKV 0.017% (0.000-0.093). The overall specificity for the cobas CHIKV/DENV and cobas Zika tests was 100% (99.959-100). For the simultaneous assay testing, 960 test results were available in 7 hours and 53 minutes. CONCLUSION: Detection of CHIKV, DENV, and ZIKV RNA in donor samples in Vietnam and Thailand indicate the presence of the virus in asymptomatic blood donors. The cobas 6800/8800 systems (Roche Molecular Systems, Pleasanton, CA) enable screening blood donations in endemic areas for these viruses together or separately.

Sensitivity and specificity of a new automated system for the detection of hepatitis B virus, hepatitis C virus, and human immunodeficiency virus nucleic acid in blood and plasma donations.

BACKGROUND: Use of nucleic acid testing (NAT) in donor infectious disease screening improves transfusion safety. Advances in NAT technology include improvements in assay sensitivity and system automation, and real-time viral target discrimination in multiplex assays. This article describes the sensitivity and specificity of cobas MPX, a multiplex assay for detection of human immunodeficiency virus (HIV)-1 Group M, HIV-2 and HIV-1 Group O RNA, HCV RNA, and HBV DNA, for use on the cobas 6800/8800 Systems. STUDY DESIGN AND METHODS: The specificity of cobas MPX was evaluated in samples from donors of blood and source plasma in the United States. Analytic sensitivity was determined with reference standards. Infectious window periods (WPs) before NAT detectability were calculated for current donor screening assays. RESULTS: The specificity of cobas MPX was 99.946% (99.883%-99.980%) in 11,203 blood donor samples tested individually (IDT), 100% (99.994%-100%) in 63,012 donor samples tested in pools of 6, and 99.994% (99.988%-99.998%) in 108,306 source plasma donations tested in pools of 96. Seven HCV NAT-yield donations and one seronegative occult HBV infection were detected. Ninety-five percent and 50% detection limits in plasma (IU/mL) were 25.7 and 3.8 for HIV-1M, 7.0 and 1.3 for HCV, and 1.4 and 0.3 for HBV. The HBV WP was 1 to 4 days shorter than other donor screening assays by IDT. CONCLUSION: cobas MPX demonstrated high specificity in blood and source plasma donations tested individually and in pools. High sensitivity, in particular for HBV, shortens the WP and may enhance detection of occult HBV.

Screening of Blood Donations for Zika Virus Infection - Puerto Rico, April 3-June 11, 2016.

Transfusion-transmitted infections have been documented for several arboviruses, including West Nile and dengue viruses (1). Zika virus, a flavivirus transmitted primarily by Aedes aegypti mosquitoes that has been identified as a cause of congenital microcephaly and other serious brain defects (2), became recognized as a potential threat to blood safety after reports from a 2013-2014 outbreak in French Polynesia. Blood safety concerns were based on very high infection incidence in the population at large during epidemics, the high percentage of persons with asymptomatic infection, the high proportion of blood donations with evidence of Zika virus nucleic acid upon retrospective testing, and an estimated 7-10-day period of viremia (3). At least one instance of transfusion transmission of Zika virus has been documented in Brazil after the virus emerged there, likely in 2014 (4). Rapid epidemic spread has followed to other areas of the Americas, including Puerto Rico.

Comparative yield of HCV RNA testing in blood donors screened by 2.0 versus 3.0 antibody assays.

BACKGROUND: Two HCV antibody tests (EIA 2.0 [EIA2], Abbott; and the Version 3.0 ELISA [EIA3], Ortho) are currently licensed for screening of US blood donors. Testing of donors for HCV RNA allows comparison of the sensitivities of the two antibody-screening assays. STUDY DESIGN AND METHODS: All allogeneic blood donations at 13 US test sites were screened for HCV RNA by testing plasma minipools using an investigational assay (COBAS AmpliScreen HCV test, v2.0, Roche Molecular Systems). Some sites screened for HCV antibody by EIA2 and some used EIA3. The frequency of RNA-positive and antibody-negative (RNA-pos and Ab-neg) donations among donors screened by each antibody assay was compared. Antibody appearance was assessed in a donor follow-up study. RESULTS: A total of 5.51 x 10(6) donations were screened for HCV RNA. Of these, 2.27 million were screened for antibody by EIA2, and 3.24 million by EIA3. Twenty-three donations were HCV RNA-pos and Ab-neg. The frequency of RNA-pos and Ab-neg donations was higher among donations screened by EIA2 (1 in 134,000), compared to those screened by EIA3 (1 in 540,000) (p = 0.001). Of the 17 RNA-pos and Ab-neg donations identified by test sites that used EIA2, 14 were retested by EIA3 and 10 (71%) were reactive. Most RNA-pos and Ab-neg donors appear to be in the process of seroconversion. Donors that were initially EIA2-negative and EIA3-reactive showed a more prolonged pattern of seroconversion compared to those that were initially nonreactive by both antibody assays. Four donors were EIA2-negative, EIA3-reactive, and RIBA-indeterminate (c33c) for at least 90 days, 1 for more than 317 days. CONCLUSION: EIA3 would have detected the majority of RNA-positive donations missed by EIA2. Some RNA-positive donors are EIA2-negative and EIA3-reactive for a prolonged period of time.