Canadian Blood Donors Research Articles

Weak D type 67 in four related Canadian blood donors

Abstract Correct donor D typing is critical to prevent recipient alloimmunization. No method can detect all variants, and the immunogenicity of many variants is unknown. Routine ABO and D serologic typings are performed in our laboratory by automated microplate testing. Until 2011, routine confirmation of D– status of first-time donors was performed by the manual tube indirect antiglobulin test (IAT); this was replaced by automated solid-phase testing including weak D testing by IAT. Selected donors are investigated by other methods. We describe four weak D type 67 (RHD*01W.67) donors whose samples tested as D– by automated microplate and manual methods but were later determined to be D+ by automated solid-phase and RHD gene analysis. Solid-phase serologic and molecular typing results of all four donors were identical. It was identified that the donors are of English-Irish descent; two are brothers and the others are cousins. Transfusion of blood from one of these donors likely resulted in alloimmunization to D in one of three recipients tested since no other documented exposures were identified. Lookback studies determined that two other D– recipients were not alloimmunized. Immunohematology 2015;31:159–162.

The epidemiology of human T‐cell lymphotropic virus types I and II in Canadian blood donors

Blood donors in Canada have been tested for Human T-Cell Lymphotropic Virus (HTLV) since 1990. We report the epidemiology, risk factors and lookback/traceback of HTLV-positive donors/recipients. The annual HTLV rate was calculated from 1990 to 2010. Residual risk was estimated as the product of incidence and window period. Twenty-nine HTLV-positive donors and 116 matched controls (ratio 1 : 4) were interviewed about risk factors. For HTLV-positive donations, lookback investigations involved identification of all previous donations, and attempting to locate and test recipients. Traceback was initiated when transfusion transmission was queried for HTLV-positive blood recipients. All donors of products that the recipient received were identified, with an attempt to locate and test them. The HTLV rate decreased from 9.35 per 100,000 donations in 1990 to 1.11 in 2010. The residual risk of infection was 1 in 7.6 million donations. In logistic regression birth overseas (OR 18.7), history of sexually transmitted diseases (OR 32.9), sex with unknown background (OR 5.4) and blood transfusion (OR 8.9) were significant predictors. In the lookback study, of 109 HTLV-positive donors, 508 components were transfused, of whom 147 recipients were tested and 18 (12%) were positive. All were transfused prior to the implementation of donor testing. Twenty-three traceback investigations were requested involving 324 transfused untested products,of whom 219 (67.6%) of donors were tested and 13 (6%) were positive for HTLV. With testing of the blood supply, the risk from HTLV is very low and while most HTLV-positive donors have risk factors, deferrable risk is rare.

O54 A follow-up study on Canadian blood donors testing positive for hepatitis B anti-core antibody (anti-HBc)

O54 A follow-up study on Canadian blood donors testing positive for hepatitis B anti-core antibody (anti-HBc)

West Nile virus in Canadian blood donors

Blood donation screening for West Nile virus (WNV) RNA by nucleic acid testing (NAT) was implemented in Canada in July 2003, and 14 WNV RNA-positive donations were identified. Samples were screened in minipools of six donations with a WNV assay (TaqScreen, Roche). Two of the donors were identified by single-donor screening that was initiated in the province of Saskatchewan, which had the highest prevalence of WNV in the country, in early September 2003. The original 14 samples and follow-up samples (2-35 days after donation), available from 13 of the 14 donors were tested with an in-house, real-time, quantitative WNV NAT assay that was specific for WNV. A Health Canada reference reagent was used for calibration. Immunoglobulin M (IgM) and immunoglobulin G (IgG) levels were determined with commercial enzyme-linked immunosorbent assay kits. All donors tested positive for the presence of WNV with the in-house assay. Two donors, 18 and 19, identified by single-donor testing, had extremely low levels of viremia and that could only be detected in 1:38 or 1:39 replicate tests. The titers of the remaining index samples ranged from below log2.8 (the limit of quantitation) to log4.7 NAT detectable units per mL. Three samples, from Donors 17, 18, and 19, were IgM-positive, whereas samples from Donors 18 and 19 were also IgG-positive. The remaining 10 donors with follow-up samples all seroconverted. The 14 WNV donor samples detected by routine screening were confirmed as WNV RNA-positive by a WNV RNA-specific in-house assay and by demonstration of seroconversion in 13 of the 14 donors.

Prevalence of GBV-C/Hepatitis G Virus Viremia and Anti-E2 in Canadian Blood Donors

Background and Objectives: GB virus C (GBV-C)/hepatitis G virus (HGV) is a recently recognized parenterally and sexually transmitted agent. The prevalence of GBV-C/HGV markers in Canadian blood donors has not been previously studied and was therefore determined. Materials and Methods: Blood donors [identity unlinked (IU), short-term temporarily deferred (STTD) and autologous groups] and donor samples with antibodies to hepatitis C (anti-HCV) or hepatitis B core were tested for GBV-C/HGV RNA and for antibodies to E2 antigen (anti-E2). Results: GBV-C/HGV RNA was found in 1.1% and anti-E2 in 7.3% of the combined IU/STTD donor group. Viremia was much more common in anti-HCV-positive samples (12.5%); anti-E2 was present in >50% of this group. In the STTD group, female gender was significantly associated with viremia. Conclusion: GBV-C/HGV infection is relatively common in Canadian donors, and a small proportion are viremic. The association of female gender and viremia was unexpected. Further study is needed to clarify the epidemiology and natural history of GBV-C/HGV infection.

Prevalence of GBV‐C/Hepatitis G Virus Viremia and Anti‐E2 in Canadian Blood Donors

Abstract Background and Objectives: GB virus C (GBV‐C)/hepatitis G virus (HGV) is a recently recognized parenterally and sexually transmitted agent. The prevalence of GBV‐C/HGV markers in Canadian blood donors has not been previously studied and was therefore determined. Materials and Methods: Blood donors [identity unlinked (IU), short‐term temporarily deferred (STTD) and autologous groups] and donor samples with antibodies to hepatitis C (anti‐HCV) or hepatitis B core were tested for GBV‐C/HGV RNA and for antibodies to E2 antigen (anti‐E2). Results: GBV‐C/HGV RNA was found in 1.1% and anti‐E2 in 7.3% of the combined IU/STTD donor group. Viremia was much more common in anti‐HCV‐positive samples (12.5%); anti‐E2 was present in >50% of this group. In the STTD group, female gender was significantly associated with viremia. Conclusion: GBV‐C/HGV infection is relatively common in Canadian donors, and a small proportion are viremic. The association of female gender and viremia was unexpected. Further study is needed to clarify the epidemiology and natural history of GBV‐C/HGV infection.

Correlations among human plasma levels of dioxin-like compounds and polychlorinated biphenyls (PCBs) and implications for epidemiologic studies.

In studies of the potential health effects of background-level exposure to organochlorine compounds (e.g., polychlorinated biphenyls, polychlorinated dibenzodioxins, and polychlorinated dibenzofurans), investigators have often measured either polychlorinated biphenyls or polychlorinated dibenzodioxins/polychlorinated dibenzofuransbut not both. We measured polychlorinated biphenyls (including specific non-, mono-, and di-ortho congeners) and specific polychlorinated dibenzodioxins/dibenzofurans among 63 Canadian blood donors. Levels of these compounds were, in general, fairly correlated. For example, Pearson's correlation coefficient between log total polychlorinated biphenyl and log total polychlorinated dibenzodioxins was .52. These results suggest that in epidemiologic studies of health effects of background-level exposures to these compounds, the quantitative dose-response relation observed for a given compound (or class of compounds acting through a similar mechanism) may easily be miscalibrated or confounded.

The Effect of Age and Occupation on the Seroprevalence of Helicobacter pylori Infection

Serological studies in developed and developing countries using enzyme-linked immunosorbent assays have validated this technique as a rapid, noninvasive method for the diagnosis of Helicobacter pylori infections. The prevalence of serum antibodies to H pylori was studied in 473 Canadian blood donors from Manitoba, 212 healthy Japanese. and 226 healthy Americans. As expected, the seroprevalence rose progressively with age in the three populations and reached its peak (greater than 55%) in subjects 60 years of age and older. The seroprevalence did not decrease in elderly persons (60 to 99 years), indicating a persistent immune response. More detailed analysis was perfom1ed on the Canadian population. Age-adjusted prevalence rates in men and women were similar. Among young adults (15 to 29 years). farmers had a significantly higher seroprevalence rate than white-collar or blue-collar workers. but in older persons occupational rates were similar. A multiple linear regression analysis of the data confirmed that age and occupation in young adults were both significantly associated with seroprevalence of H pylori infections.

Prevalence of delta agent among Canadian blood donors

Prevalence of delta agent among Canadian blood donors