Parvovirus b19 infections and blood counts in blood donors

Parvovirus B19 remains an underestimated pathogen among infections during gestation in Argentina: Insights through the study of symptomatic and asymptomatic pregnant patients and newborns from Córdoba

BACKGROUND

Parvovirus B19 (B19 V) infection during pregnancy can cause adverse fetal outcomes. Our aim was to characterize both clinical and asymptomatic maternal and neonatal cases by studying virological and serological markers of B19 V infection, and to sequence the complete genome of the circulating virus in Argentina.

METHODS

Symptomatic patients were included based on maternal and/or fetal-neonatal signs attributable to B19 V infection during gestation. Pregnant patients were analyzed in either the timely diagnosis group (TD, samples obtained when symptoms were present and infection was suspected) or the retrospective diagnosis group (RD, samples collected immediately postpartum), and newborns were analyzed at birth. A sample of asymptomatic individuals was also analyzed. Diagnostic tests (PCR/qPCR/serology) and sequencing were performed on archived serum samples from 2018 to 2023, and clinical data were obtained from medical records.

RESULTS

We studied 328 symptomatic patients, including 185 pregnant patients (73 TD and 112 RD) and 143 newborns. Among them, we identified 27/328 (8.2 %) positive cases (B19V+): 12/73 (16.4 %) in the TD group, 6/112 (5.4 %) in the RD group, and 9/143 (6.3 %) newborns. Within the 77 mother-newborn pairs included, there were 8 (10.4 %) B19 V infections and 6 cases of vertical transmission. Additionally, B19 V infection was detected in 26/310 (8.4 %) asymptomatic patients. Phylogenetic analysis identified genotype 1a as a circulating strain in Argentina.

CONCLUSIONS

Our findings highlight the need to raise awareness and enhance diagnostic approaches in Argentina to more effectively identify and manage B19 V infections during pregnancy in our region.

Ensuring Transfusion Safety: Screening Blood Donors for Human Parvovirus B19

Ensuring the safety of blood and blood products is a vital aspect of healthcare. The potential for transmission of pathogens through blood and blood products makes transfusion safety a significant concern. Despite advancements in testing methodologies, donated blood products still pose a risk for infection transmission. Human parvovirus B19 (B19V) is a small, single-stranded, non-enveloped DNA virus transmissible parenterally by blood transfusion. B19V causes a wide range of clinical manifestations, which is generally harmless in healthy individuals. B19V infection may cause severe complications, such as aplastic crises, as it affects erythrocyte progenitor cells in individuals with increased erythrocyte turnover. Additionally, B19V can be transmitted from pregnant women to their foetus, potentially causing hydrops fetalis and foetal death. The potential for transmission through blood and blood products makes B19V a significant concern for transfusion safety. In response to the growing recognition of B19V's impact on transfusion safety, various international health organisations have introduced guidelines to minimise its transmission through blood and plasma products. However, the implementation of these guidelines varies globally, with some regions, such as India, still lacking formal protocols for B19V monitoring. This review article explores the existing methodologies for screening blood donors for B19V, assesses the associated transfusion risks, and considers the implications for public health and clinical practice. By emphasising advancements in diagnostic techniques and the challenges of their implementation, this article provides a comprehensive overview of efforts to reduce the transmission of B19V through blood transfusions, thereby ensuring safer blood supplies and improved patient outcomes.

Molecular and serological markers of human parvovirus B19 infection in blood donors: A systematic review and meta-analysis

BACKGROUND:

Human parvovirus B19 (B19V) is one of the blood-borne viruses. The virus can be transmitted to susceptible individuals by blood or blood products. The virus is not associated with significant disease in general population, while people with underlying problems such as immunodeficiency can cause anemia and arthritis. The current systematic review and meta-analysis aimed to estimate the overall prevalence of B19V DNA, anti-B19V IgG, and anti-B19V IgM antibodies in blood donors worldwide.

METHODS:

A systematic search was carried out in online databases for relevant studies from inception until March 30, 2019. Study selection was performed based on predesigned eligibility criteria. The proportion of B19V DNA, anti-B19V IgG, and anti-B19V IgM antibodies were pooled using the inverse variance method. All statistical analyses were performed using the R version 3.5.3, package “meta.”

RESULTS:

According to the random-effects model, the pool prevalence of B19V DNA, anti-B19V IgM, and anti-B19V IgG among blood donors was calculated to be 0.4% (95% confidence interval [CI] =0.3%–0.6%), 2.2% (95% CI = 1.3%–3.7%), and 50.1% (95% CI = 43.1%–57.1%), respectively.

CONCLUSION:

For the transmission of B19V through blood, the presence of the virus genome is required, and the present study showed that the prevalence of the virus genome in blood donors is <1%. Therefore, there is no need to screen donated blood for B19V infection.

Human parvovirus B19 frequency among blood donors after an epidemic outbreak: relevance of the epidemiological scenario for transfusion medicine

A retrospective, cross-sectional study was conducted to determine the frequency of human parvovirus B19 (B19V) infected individuals, viral loads and immunity among blood donors from Argentina, in a post-epidemic outbreak period. B19V DNA and specific IgG were tested in minimum study samples of donors attending a blood bank at Córdoba, Argentina, in 2014. Anti-B19V IgM and viral loads were determined in B19V-positive plasma samples. Seven of 731 samples (0.96%) resulted positive, corresponding to individuals aged 32-53 years, four of them repeat donnors and three first-time donors. Viral loads were <10³ IU/mL. None had IgM and 6/7 had IgG, one of them at a high level (in the range of 100-200 IU/ml, and the remaining 5 at low to medium level, 5-50 IU/ml). Thus one case was classified as acute infection (DNA+/IgM-/IgG-) and six as potentially persistent infections (DNA+/IgM-/IgG+). No coinfections with other pathogens of mandatory control in the pre-transfusion screening were detected. Prevalence of IgG was 77.9% (279/358). This study provides the first data of B19V prevalence in blood donors in Argentina, demonstrating high rates of acute and persistent B19V infections and high prevalence of anti-B19V IgG in a post-epidemic period. Further research is needed to elucidate mechanisms/factors for B19V persistence as well as follow-up of recipients in the context of haemo-surveillance programs, contributing to the knowledge of B19V and blood transfusion safety.

Parvovirus B19 seroprevalence, viral load, and genotype characterization in volunteer blood donors from southern Brazil

Usually transmitted via respiratory droplets, parvovirus B19 (B19V) can also be acquired by blood transfusion especially because of viral persistence, resistance to blood treatment procedures, and high viral load during the early infection phase. This is particularly problematic in immunocompromised or anemic patients where the infection can have a severe outcome. As B19V DNA was detected in blood donations from South Brazil during a viral metagenomic survey performed by Next-Generation Sequencing, the objective of this retrospective study was to evaluate the seroprevalence, B19V DNA presence and circulating genotypes in a Hospital Blood Transfusion Service in Santa Maria city in South Brazil (Rio Grande do Sul state). Among 480 volunteer blood donors, 53.9% (n = 258 of 479) were anti-B19V IgG-positive, and 9 (1.9%) plasma samples presented B19V DNA. In almost all cases (n = 7 of 9, 77.8%), B19V DNA load was accompanied by the presence of anti-B19V IgG suggesting a persistent infection. The sequencing of the strains demonstrated that all belong to genotype 1 which is the most prevalent worldwide. The analysis of the recipient information of the positive for B19V DNA units revealed no related posttransfusion adverse effects. Our results demonstrate for the first time, B19V seroprevalence, viral load, and genotypes among blood donors from South Brazil and give a light for the circulation and impact of this B19V in this part of the country.

Parvovirus B19 in South African blood donors

BACKGROUND

Parvovirus B19 (PVB19) is transmitted via transfusion of blood and blood products. PVB19 is resistant to viral inactivation methods, which poses a threat to blood safety. We investigated the prevalence of PVB19 antibodies and DNA in healthy blood donors from the South African National Blood Bank Service to evaluate the necessity of PVB19 DNA testing.

STUDY DESIGN AND METHOD

A retrospective analysis of 1500 residual plasma specimens from healthy blood donors from the SANBS repository were screened in mini-pools of 20 for PVB19 DNA using a quantitative polymerase chain reaction (PCR). Positive pools were resolved by individual viral load testing and screened for PVB19 immunoglobulin M (IgM) and immunoglobulin G (IgG) antibodies to correlate viral loads with serological status. PVB19 IgG prevalence was determined by testing 90 randomly selected specimens from the 1500 plasma specimens.

RESULTS

The prevalence of PVB19 IgG, IgM and IgG, and DNA was 62.2%, 0.06%, and 0.9%, respectively. Fourteen of the 1500 blood donor specimens received, had detectable PVB19 viral loads. Nine of the fourteen donors with detectable viral loads were PVB19 IgG seropositive. The PVB19 viral loads ranged from 1.81 to 5.32 log IU/mL. Four of the fourteen viraemic donors had a viraemia >10 ⁴ IU/mL.

CONCLUSION

We have demonstrated a low prevalence of PVB19 DNA in SANBS blood donors. The predominance of low-level viraemia and the presence of PVB19 antibodies, suggests that the risk of transfusion transmission of PVB19 among SANBS donors may be relatively low.

Parvovirus B19: What Is the Relevance in Transfusion Medicine?

Parvovirus B19 (B19V) has been discovered in 1975. The association with a disease was unclear in the first time after the discovery of B19V, but meanwhile, the usually droplet transmitted B19V is known as the infectious agent of the “fifth disease,” a rather harmless children’s illness. But B19V infects erythrocyte progenitor cells and thus, acute B19V infection in patients with a high erythrocyte turnover may lead to a life-threatening aplastic crisis, and acutely infected pregnant women can transmit B19V to their unborn child, resulting in a hydrops fetalis and fetal death. However, in many adults, B19V infection goes unnoticed and thus many blood donors donate blood despite the infection. The B19V infection does not impair the blood cell counts in healthy blood donors, but after the acute infection with extremely high DNA concentrations exceeding 10¹⁰ IU B19V DNA/ml plasma is resolved, B19V DNA persists in the plasma of blood donors at low levels for several years. That way, many consecutive donations that contain B19V DNA can be taken from a single donor, but the majority of blood products from donors with detectable B19V DNA seem not to be infectious for the recipients from several reasons: first, many recipients had undergone a B19V infection in the past and have formed protective antibodies. Second, B19V DNA concentration in the blood product is often too low to infect the recipient. Third, after the acute infection, the presence of B19V DNA in the donor is accompanied by presumably neutralizing antibodies which are protective also for the recipient of his blood products. Thus, transfusion-transmitted (TT-) B19V infections are very rarely reported. Moreover, in most blood donors, B19V DNA concentration is below 1,000 IU/ml plasma, and no TT-B19V infections have been found by such low-viremic donations. Cutoff for an assay for B19V DNA blood donor screening should, therefore, be approximately 1,000 IU/ml plasma, if a general screening of blood donors for single donation blood components is considered at all: for the overwhelming majority of transfusion recipients, B19V infection is not relevant as well as for the blood donors. B19V DNA screening of vulnerable patients after transfusion seems to be a more reasonable approach than general blood donor screening.

Metagenomics analysis of red blood cell and fresh-frozen plasma units

BACKGROUND

Although the risk of transmitting infectious agents by blood transfusion is dramatically reduced after donor selection, leukoreduction, and laboratory testing, some could still be present in donor's blood. A description of metagenomes in blood products eligible for transfusion represents relevant information to evaluate the risk of pathogen transmission by transfusion.

STUDY DESIGN AND METHODS

Detection of viruses, bacteria, and fungi genomes was made by high-throughput sequencing (HTS) of 600 manufactured blood products eligible for transfusion: 300 red blood cell (RBC) and 300 fresh-frozen plasma (FFP) units.

RESULTS

Anelloviruses and human pegivirus, frequent in the blood of healthy individuals, were found. Human papillomavirus type 27 and Merkel cell polyomavirus, present on the skin, were also detected. Unexpectedly, astrovirus MLB2 was identified and characterized in a FFP unit. The presence of astrovirus MLB2 was confirmed in donor's blood and corresponded to an asymptomatic acute viremia. Sequences of bacteria and fungi were also detected; they are likely the result of environmental contamination.

CONCLUSION

This study demonstrates that HTS is a promising tool for detecting common and less frequent infectious pathogens in blood products.

Human Parvoviruses

Parvovirus B19 (B19V) and human bocavirus 1 (HBoV1), members of the large Parvoviridae family, are human pathogens responsible for a variety of diseases. For B19V in particular, host features determine disease manifestations. These viruses are prevalent worldwide and are culturable in vitro, and serological and molecular assays are available but require careful interpretation of results. Additional human parvoviruses, including HBoV2 to -4, human parvovirus 4 (PARV4), and human bufavirus (BuV) are also reviewed. The full spectrum of parvovirus disease in humans has yet to be established. Candidate recombinant B19V vaccines have been developed but may not be commercially feasible. We review relevant features of the molecular and cellular biology of these viruses, and the human immune response that they elicit, which have allowed a deep understanding of pathophysiology.

Frequency and significance of parvovirus B19 infection in patients with rheumatoid arthritis

The present study aims to clarify the possible involvement of parvovirus B19 (B19V) infection in rheumatoid arthritis (RA) pathogenesis by investigating the presence of B19V infection markers (genomic sequences and virus-specific antibodies) in association with the level of cytokines and RA clinical activity and aggressiveness. A total of 118 RA patients and 49 age- and sex-matched healthy volunteers were enrolled in the study. Nested PCR was used to detect B19V sequences in whole blood and cell-free plasma DNA, ELISA to detect virus-specific antibodies and cytokine levels in plasma and recomLine dot blot assay for antibodies to separate B19V antigens. The detection frequency of B19V DNA was higher in patients with RA (25.4 %) in comparison with healthy persons (18.4 %). B19V DNA in cell-free plasma (B19⁺p) was detected significantly often in RA patients in comparison with healthy controls (13.6 vs 2 %; P=0.0002). RA B19⁺p patients had higher disease activity and aggressiveness, decreased haemoglobin and increased erythrocyte sedimentation rates. IL-6 plasma levels were significantly higher in RA patients than in controls. Within the RA patients’ group the IL-6 level was significantly increased in B19⁺p patients with disease activity scores of DAS28>5.2, high C-reactive protein and low haemoglobin. Contrary to the healthy controls, the majority of RA B19⁺p patients did not have antibodies to VP-1S (VP1u) and VP-N (N-terminal half of structural proteins VP1 and VP2), which correspond to the epitopes of neutralizing antibodies. These results indicate that B19V infection at least in some patients is involved in RA pathogenesis.

Prevalence and Viral Load of Human Parvovirus B19 (B19V) Among Blood Donors in South-East Brazil

The infection of human parvovirus B19 (B19V) is a common event in the general population, including volunteer blood donors. In some cases it can be asymptomatic and can remain persistent for a long period of time. The objective of this study was to examine the B19V DNA prevalence and viral load in first-time volunteer blood donors. Blood samples were collected from 91 primary blood donors at the Regional Blood Center of Ribeirão Preto, Southeast Brazil. Viral detection and quantitation was performed by an in-house TaqMan(®) real-time PCR with high sensitivity. B19V DNA was detected in one male blood donor (1.0 %) and was characterized by a very low viral load (537.36 copies/mL). Our studies demonstrate that B19V DNA at low titer may be present in apparently healthy individuals. Sensitive molecular diagnostic tools can be applied for the screening of fresh blood derived products in order to prevent transfusion-transmitted B19V infection.

Look-back study on recipients of Parvovirus B19 (B19V) DNA-positive blood components

BACKGROUND AND OBJECTIVES

To assess the relevance of Parvovirus B19 (B19V) DNA at low to intermediate concentrations in blood donors for the recipients of their blood components.

MATERIAL AND METHODS

We studied recipients of B19V DNA-positive blood components [red blood cell concentrates (RBCs), pooled platelet concentrates and fresh frozen plasma]. This included archived pretransfusion samples as well as follow-up samples investigated by ELISA or NAT and genome sequence analysis.

RESULTS

In 132 out of 424 recipients, we could detect no anti-B19V IgG before transfusion. In 67 out of 132 sero-negative recipients, a follow-up sample was available. Sixty-five of these received blood components from donors with <10(4) IU B19V DNA/ml plasma and had no evidence of transfusion-transmitted (TT)-B19V infection. Homology in genome sequences in donor and recipient provided evidence for a TT-B19V infection in two recipients. Both patients received RBC containing 3.4 × 10(6) and 1.8 × 10(4) IU B19V DNA/ml plasma, respectively. The anti-B19V IgG titres in the donors were 2 and 76 IU/ml plasma, respectively. The antibodies in the second donor were directed against capsid proteins and are thus considered as potential neutralizing antibodies.

CONCLUSIONS

TT-B19V infections through blood components with low (<10(4) IU/ml plasma) B19V DNA concentrations did not occur in our study. One of the TT-B19V infections occurred from RBC with intermediate B19V DNA concentration despite the presence of potential neutralizing antibodies in the donor, but its clinical significance was low.

Persistence of Parvovirus B19 (B19V) DNA and humoral immune response in B19V-infected blood donors

BACKGROUND AND OBJECTIVES

Parvovirus B19 (B19V) DNA seems to persist in the plasma of B19V-infected blood donors. The relevance of this for recipients of single-donor blood components is yet unclear.

MATERIAL AND METHODS

We studied serial archive and follow-up samples from 75 B19V-infected blood donors to obtain more data about the duration and degree of viraemia and the presence of IgG and IgM anti-B19V. IgG antibodies were further characterized by Western blot analysis in 29 donors.

RESULTS

In 411 B19V DNA-positive samples collected, we found high concentrations (>10(6) IU B19V DNA/ml plasma) in five. B19V DNA persisted for a mean of 21·5 months (range: 2·3-52·4; 95% confidence interval, 19·1-23·9 months) in all donors. Only 15 such samples had either no or low-titre IgG anti-B19V. IgG antibodies were predominantly directed against epitopes on the minor capsid protein VP1, thus probably of neutralizing type with high avidity. IgM anti-B19V was detectable in 9/13 samples with high DNA concentrations.

CONCLUSIONS

The vast majority of single-donor blood components with detectable B19V DNA are probably not infectious for their recipients because DNA is at only low levels and the donors also have potentially neutralizing antibodies with high avidity. Anti-B19V IgM testing does not identify every donation with high B19V DNA concentrations, but, in addition to B19V NAT testing, donors with persistent IgG anti-B19V might be considered 'B19V-safe' for single-donor blood components.