The residual risk of transfusion-transmitted cytomegalovirus infection associated with leucodepleted blood components

Human T-lymphotropic virus in Irish blood donors: Impact on future testing strategy

Aim

A risk‐based approach to the testing of blood donations for Human T‐Lymphotropic Virus (HTLV) should include an assessment of blood donation seroepidemiology. The objectives of the present study were to determine the proportion of HTLV positive units in Irish blood donations, and subsequently, to estimate the current risk of transfusion transmitted HTLV (TT‐HTLV).

Methods

Over 3 million donations screened between 1996 and 2020, were included in the study (n = 3,666,253). Factors considered in the assessment of TT‐HTLV risk included: (I) HTLV seropositivity, (ii) probability of a leucodepletion failure, and (iii) the HTLV testing strategy.

Results

Six HTLV positive donations were detected throughout the study period, all of them in previously unscreened blood donors (0.000164%; n = 6/3,666,253), 3 of whom had donated prior to the introduction of HLTV antibody testing. On average 0.11% of manufactured blood components assessed, failed to satisfy the leucodepletion quality assurance criteria of less than 1 × 10⁶ cells/unit. In using these values to model the risk of TT‐HTLV, it was shown that the combination of leucodepletion with either universal screening of all = donors, or selective testing of first‐time donors, a possible HTLV transfusion transmitted infection would be prevented every 468–3776 years.

Conclusions

This is the first report on the proportion of HTLV positive in Irish blood donations (1996–2020) and will be used to inform blood donation screening policy in Ireland. Evidence is provided for recommending a selective HTLV donor screening algorithm in Ireland that is accompanied by a robust framework for continued surveillance of leucodepletion failure rate.

A Centre-Based Comparison of Double vs Single Prevention Strategy on Transfusion Transmitted-Cytomegalovirus in At-Risk Haemopoietic stem cell transplant Patients and a State Survey on CMV-Seronegative Ordering Practices

BACKGROUND AND OBJECTIVES

Universal leucocyte depletion reduces the risk of transfusion transmitted Cytomegalovirus; however, many clinicians still prescribe Cytomegalovirus seronegative units. Our retrospective study aims to confirm the low risk of transfusion transmitted Cytomegalovirus with leucocyte depletion alone and demonstrate the ongoing variability in Cytomegalovirus seronegative transfusion prescribing.

MATERIALS AND METHODS

Over a 9 year period (7/2009-7/2018), occurrences of transfusion transmitted Cytomegalovirus in Cytomegalovirus seronegative donor/recipient haemopoietic stem cell transplant pairs were compared at one allogeneic haemopoietic stem cell transplant centre providing Cytomegalovirus seronegative blood products and leucocyte depletion (double prevention) versus another providing leucocyte depletion only (single prevention). Retrospective chart audit identified patient demographics, blood product exposure and Cytomegalovirus infection by polymerase chain reaction. A separate audit examined Cytomegalovirus seronegative blood product ordering in a broader range of hospital types.

RESULTS

We identified 122 and 66 Cytomegalovirus negative donor/recipient haemopoietic stem cell transplant pairs using double and single transfusion prevention strategy respectively. Transfusion exposure to red cells and pooled platelets was similar, though more apheresis platelets were used in the double prevention group. Cytomegalovirus infection rate was 3 (2.4%) and zero in the double and single prevention groups respectively. Cytomegalovirus seronegative unit ordering was not limited to hospitals with obstetric or neonatal populations, suggesting ongoing reliance of Cytomegalovirus seronegative units outside this population.

CONCLUSION

The analysis suggests a double prevention strategy does not provide additional protection against transfusion transmitted Cytomegalovirus. There is ongoing variability in the acceptance of leucocyte depletion alone despite the low risk of Cytomegalovirus infection This article is protected by copyright. All rights reserved.

Transfusion-transmitted and community-acquired cytomegalovirus infection in seronegative solid organ transplant recipients receiving seronegative donor organs

Solid organ transplant (SOT) recipients who are cytomegalovirus (CMV) seronegative (R-) and receive seronegative donor (D-) organs have a small but currently unquantified risk of both transfusion-transmitted CMV (TT-CMV) and community-acquired CMV (CA-CMV). We retrospectively studied the incidence and clinical symptoms of TT-CMV (infection <1 year posttransplant) and CA-CMV (infection >1 year posttransplant) in a cohort of D-/R- adult and pediatric SOT recipients receiving leukoreduced blood products not screened for CMV seronegativity transplanted at our center between 2000 and 2011. CMV infection was defined as IgG seroconversion or detectable CMV antigenemia/DNAemia. Among 536 consecutive D-/R- recipients, 398 (81.8%) had adequate follow-up, and 231 (58%) received cellular blood products (total: 1626 red blood cell units, 470 platelet units) 30 days pretransplant to 90 days posttransplant. We observed no confirmed TT-CMV cases, but 14 CA-CMV cases (64% symptomatic) were seen. The estimated incidence rate of CA-CMV was higher in children (3.0/100 patient years) than adults (0.46/100 patient years, incident rate ratio of 6.52). The absence of TT-CMV over 11 years suggests neither seronegative blood products nor CMV DNA blood donor screening would provide significant incremental safety when blood is already leukoreduced. D-/R- SOT recipients, particularly children, have a significantly higher and ongoing risk of CA-CMV.

Neonatal red blood cell transfusion

Transfusions are more common in premature infants with approximately 40% of low birth weight infants and up to 90% of extremely low birth weight infants requiring red blood cell transfusion. Although red blood cell transfusion can be life-saving in these preterm infants, it has been associated with higher rates of complications including necrotizing enterocolitis, bronchopulmonary dysplasia, retinopathy of prematurity and possibly abnormal neurodevelopment. The main objective of this review is to assess current red blood cell transfusion practices in the neonatal intensive care unit, to summarize available neonatal transfusion guidelines published in different countries and to emphasize the wide variation in transfusion thresholds that exists for red blood cell transfusion. This review also addresses certain issues specific to red blood cell processing for the neonatal population including storage time, irradiation, cytomegalovirus (CMV) prevention strategies and patient blood management. Future research avenues are proposed to better define optimal transfusion practice in neonatal intensive care units.

Infectious complications in neonatal transfusion: Narrative review and personal contribution

Neonates and prematures are among the most transfused categories of patients. Adverse reactions due to transfusions, such as transfusion-transmitted infections, can affect the rest of their lives. In this systematic review, we revised the literature concerning transfusion-transmitted infection in neonates. We reported case-reports and case-series previously published and we integrated these data with our experience at local neonatal intensive care unit. Moreover, we illustrated strategies for mitigating transfusion-transmitted infections, including donor selection and testing, pathogen inactivation technologies and combined approaches, as for Cytomegalovirus infection, integrating leukoreduction and identification of seronegative donors.

Existing and Emerging Blood-Borne Pathogens: Impact on the Safety of Blood Transfusion for the Hematology/Oncology Patient

Despite measures to mitigate risk of transfusion-transmitted infections, emerging agents contribute to morbidity and mortality. We outline the epidemiology, risk mitigation strategies, and impact on patients for Zika virus, bacteria, Babesia, and cytomegalovirus. Nucleic acid testing of blood has reduced risk of Zika infection and reduced transfusion-transmitted risk of Babesia. Other collection and testing measures have reduced but not eliminated the risk of sepsis from bacterially contaminated blood components. Cytomegalovirus has almost been eliminated by high-efficiency leukoreduction, but residual transmissions are difficult to distinguish from community-acquired infections and additional antibody testing of blood may confer further safety of susceptible recipients.

Infectious Complications of Transfusion of Blood Components

Transfusions are lifesaving but are not without some risks. During the middle of the last century, infectious complications were common from transfusions. By the mid 1980s the risk of transfusion transmission of infections became much lower. With the advent of emerging diseases, however, infectious risks became more prominent for a period of time. Now we live in a time where death from transfusion transmission is 10%–15% of all transfusion-associated deaths and is the lowest in history. As the risks are identified and new screens or processes are put in place, the associated transfusion transmission of infection will continue to have reducing risks and blood supply will continue to be safer still.

An analysis on the fate of a selection of blood products derived from cytomegalovirus-seronegative donors at three tertiary referral hospitals in Australia

BACKGROUND

Supply of cytomegalovirus (CMV)-seronegative blood products in Australia is an ongoing challenge. Requests for CMV-negative products are increasing with prediction that the demand will exceed supply by 2019. Clinical information evaluating how these products are being utilized by health providers within Australia is limited. This study aimed to identify indications for use of CMV-negative blood products and gather data to support possible practice change.

STUDY DESIGN AND METHODS

All CMV-negative products issued to three tertiary Australian hospitals from May 1, 2016, to May 31, 2016, were identified (n = 1219). This equated to 1044 red blood cell units and 175 platelet units. Data were collected on the fate of each unit. Information collected included the indication and urgency of transfusion, reason for discard, product age, and recipient CMV immunoglobulin G status.

RESULTS

Of the units issued during the audit period, 32 (2.6%) were discarded by the hospitals. Transfusion data were collected on 411 units. Of these, 136 (33.1%) were transfused to CMV-positive recipients, in most cases for hematology indications, and 67 units (16.3%) were transfused to CMV-negative requiring recipients. A total of 144 (35%) CMV-negative units were selected based on their irradiation status. Other reasons for the selection of CMV-negative units included product close to expiry (n = 134, 32.6%) or specific patient phenotype requirements (n = 31, 7.5%).

CONCLUSION

In this study, the majority of CMV-negative blood products were not used for CMV-negative requiring recipients. Alterations to inventory management would be advantageous to ensure continued supply for CMV-negative requiring recipients.

Transfusion-transmitted CMV infection - current knowledge and future perspectives

Transmission of human cytomegalovirus (CMV) via transfusion (TT-CMV) may still occur and remains a challenge in the treatment of immunocompromised CMV-seronegative patients, e.g. after stem cell transplantation, and for low birthweight infants. Measures to reduce the risk of TT-CMV have been evaluated in clinical studies, including leucocyte depletion of cellular blood products and/or the selection of CMV-IgG-negative donations. Studies in large blood donor cohorts indicate that donations from newly CMV-IgG-positive donors should bear the highest risk for transmitting CMV infections because they contain the highest levels of CMV-DNA, and early CMV antibodies cannot neutralise CMV. Based on this knowledge, rational strategies to reduce the residual risk of TT-CMV using leucoreduced blood products could be designed. However, there is a lack of evidence that CMV is still transmitted by transfusion of leucoreduced units. In low birthweight infants, most (if not all) CMV infections are caused by breast milk feeding or congenital transmission rather than by transfusion of leucoreduced blood products. For other patients at risk, no definitive data exist about the relative importance of alternative transmission routes of CMV compared to blood transfusion. As a result, only the conduction of well-designed studies addressing strategies to prevent TT-CMV and the thorough examination of presumed cases of TT-CMV will achieve guidance for the best transfusion regimen in patients at risk.

A national review of the clinical use of group O D- red blood cell units

BACKGROUND

There has been an international decline in the demand for red blood cell (RBC) units. In Australia, there has been a 21% reduction in demand between 2012 and 2015. In contrast, the demand for the "universal" group O D- RBC units is in fact proportionally increasing.

STUDY DESIGN AND METHODS

The clinical use of the entire O D- RBC distribution for a 5-week period throughout Australia was reviewed. Fate data on each unit issued (n = 9733) were collected that included the indication and urgency of transfusion, reason for discard, component age, and patient demographics.

RESULTS

A total of 74% of audit forms were returned (n = 7143). The national discard rate of issued units was 7.9%. A total of 6387 units were transfused into an estimated total of 3008 patients (55% males) with median patient age of 67 years and median RBC age of 21 days. Forty-seven percent were transfused to group O D- patients. A total of 17.4% were chosen for specific phenotype requirements, 24.5% of units were transfused close to expiry, and 24.5% were transfused into patients of other ABO groups.

CONCLUSION

The data appear broadly representative of the current transfusion and inventory management practices surrounding the use of group O D- RBC units. Strategies to reduce O D RBC demand include reevaluation of inventory holdings particularly at smaller centers, increasing the panel of phenotyped RBC units across all ABO groups, more regular rotation of units between hospitals to minimize time expiry, and continuing education for promoting transfusion of ABO-identical RBC units.

Sequence analysis of two variable cytomegalovirus genes for distinction between transfusion- and breast milk-transmitted infections in a very-low-birthweight infant

BACKGROUND

Cytomegalovirus (CMV) infections in very-low-birthweight infants can lead to serious clinical consequences. When CMV-related symptoms occur after transfusion, CMV transmission is often attributed to the transfusion products rather than to breast milk. However, it is sometimes difficult to distinguish between transfusion-transmitted and breast milk-transmitted CMV infections.

PATIENT AND METHODS

A patient was born at 27 gestational weeks with a weight of 689 g. He was transfused with leukoreduced red blood cells (LR-RBCs), which were later found to be CMV seropositive and CMV DNA positive. He was also fed with CMV DNA-positive breast milk. Thereafter, he developed CMV disease with thrombocytopenia and jaundice. To determine the route of transmission, we analyzed the sequences of two variable CMV genes, UL139 and UL146, by direct sequence analysis. We also performed deep sequence analysis to determine whether there were polyclonal CMV strains in the LR-RBCs transfused.

RESULTS

CMV DNA sequence-matching rates for the LR-RBCs and the patient's blood were 64.6% for the UL139 gene and 68.6% for the UL146 gene. In contrast, the sequences of these genes in the patient's blood were 100% matched with those in the breast milk. Furthermore, by deep sequence analysis, the CMV strain found in the patient's blood was not detected in the LR-RBCs transfused.

CONCLUSION

The results indicate that the pathogenic CMV strain was transmitted through breast milk, which is consistent with the claims that transfusion-transmitted CMV infection due to leukoreduced blood products is uncommon.

Leucoreduction of blood components: an effective way to increase blood safety?

Over the past 30 years, it has been demonstrated that removal of white blood cells from blood components is effective in preventing some adverse reactions such as febrile non-haemolytic transfusion reactions, immunisation against human leucocyte antigens and human platelet antigens, and transmission of cytomegalovirus. In this review we discuss indications for leucoreduction and classify them into three categories: evidence-based indications for which the clinical efficacy is proven, indications based on the analysis of observational clinical studies with very consistent results and indications for which the clinical efficacy is partial or unproven.