The diversity of chronic hepatitis B virus infections within blood donors in England and North Wales 2005 through 2010

Hepatitis B infections among blood donors in England between 2009 and 2018: Is an occult hepatitis B infection a risk for blood safety?

INTRODUCTION

Hepatitis B virus (HBV) is one of the most frequent infections identified in blood donors in England and represents an ongoing blood safety risk. We have analyzed markers of HBV infections in blood donors in England between 2009 and 2018 and used these to estimate the likelihood of non-detection of occult HBV infection (OBI).

METHODS

We collected epidemiological, virological, and genotyping information on HBV cases identified in England, 2009-2018. The estimated risk of non-detection and likely transmission of OBI were compared to lookback and transfusion-transmitted infections surveillance data.

RESULTS

Six-hundered and fifty-five HBV-infected blood donors were identified in England during the 10-year period; 598 chronic, 32 acute, and 25 occult HBV infections. However, most donors with chronic and occult infections were born in Eastern Europe, Africa, or Asia (451/544, 83% and 14/24, 58%); acute infections were largely seen in UK-born donors (19/28, 68%). Genotyping of 266 HBV-positive samples revealed five genotypes (A-E), reflecting ethnicity and country of birth. Most OBIs were identified in repeat donors (19/25); lookback data identified a transmission rate of 8.3%. It is estimated that at least 13 potentially infectious donations from donors with OBI remain undetected annually, equating to an overall residual transmission risk of 3.1 per million donations using our current screening strategy of HBsAg screening with HBV nucleic acid testing (NAT) in pools of 24.

CONCLUSIONS

OBI accounted for the majority of the HBV residual risk in England. Further cost-benefit analysis is required to estimate if our current HBV screening strategy should be changed.

Phylogenetic analysis reveals three distinct epidemiological profiles in Dutch and Flemish blood donors with hepatitis B virus infection

During 2006-2016, hepatitis B virus (HBV) was detected in nearly 400 blood donors in the Netherlands and Flanders. Donor demographics and self-reported risk factors as disclosed during the donor exit interview were compared to HBV phylogenies of donor and reference sequences. First-time donors with chronic HBV-infection were often immigrants (67%) infected with genetically highly diverse strains of genotypes A (32%), B (8%), C (6%), D (53%) and E to H (1%). Each subtype was strongly associated with donor ethnicity. In contrast, 57/62 (93%) of acute/recent HBV infections occurred among indigenous donors, of whom 67% was infected with one specific widely circulating epidemic HBV-A2 lineage. HBV typing identified three distinct epidemiological profiles: the import of chronic HBV infections through migration, longstanding transmission of non-epidemic HBV-A2 strains within western-Europe, and the active transmission of one epidemic HBV-A2 strain most likely fueled by sexual risk behavior.

Current concepts in the prevention of pathogen transmission via blood/plasma-derived products for bleeding disorders

The pathogen safety of blood/plasma-derived products has historically been a subject of significant concern to the medical community. Measures such as donor selection and blood screening have contributed to increase the safety of these products, but pathogen transmission does still occur. Reasons for this include lack of sensitivity/specificity of current screening methods, lack of reliable screening tests for some pathogens (e.g. prions) and the fact that many potentially harmful infectious agents are not routinely screened for. Methods for the purification/inactivation of blood/plasma-derived products have been developed in order to further reduce the residual risk, but low concentrations of pathogens do not necessarily imply a low level of risk for the patient and so the overall challenge of minimising risk remains. This review aims to discuss the variable level of pathogenic risk and describes the current screening methods used to prevent/detect the presence of pathogens in blood/plasma-derived products.

Two decades of risk factors and transfusion-transmissible infections in Dutch blood donors

BACKGROUND

Risk behavior-based donor selection procedures are widely used to mitigate the risk of transfusion-transmissible infections (TTIs), but their effectiveness is disputed in countries with low residual risks of TTIs.

STUDY DESIGN AND METHODS

In 1995 to 2014, Dutch blood donors infected with hepatitis B virus (HBV), hepatitis C virus (HCV), human immunodeficiency virus (HIV), human T-lymphotropic virus (HTLV), or syphilis were interviewed by trained medical counselors to identify risk factors associated with TTIs. Trends in the prevalence and incidence of TTIs were analyzed using binomial regression models.

RESULTS

A total of 972 new donors and 381 repeat donors had TTIs. New donors had higher rates of TTIs compared to repeat donors. Although the HBV and HCV prevalence gradually decreased over time, the incidence of all five TTIs remained stable during the past two decades. In new donors the TTIs had the following risk profiles: "blood-blood contact" for HCV, "unprotected sex" for HIV and syphilis, and "country of birth" for HBV and HTLV. In infected repeat donors, sexual risk factors predominated for all TTIs. At posttest counseling, 28% of infected repeat donors admitted to risk factors leading to permanent donor exclusion if revealed during the donor selection procedure (predominantly male-to-male sex and recent diagnosis of syphilis).

CONCLUSION

The prevalence and incidence of TTIs among Dutch blood donors are six- to 60-fold lower than in the general Dutch population, illustrating the effectiveness of donor selection procedures. However, at least a quarter of infected donors appeared noncompliant to the donor health questionnaire (DHQ), suggesting that DHQs, or the way donor questioning is implemented, can be improved.

Predonation screening of candidate donors and prevention of window period donations

BACKGROUND

Infectious window period donations slip through routine donor screening procedures. To explore the potential value of predonation screening of candidate donors, we compared the proportion of incident transfusion-transmissible infections in candidate donors, in first-time donors, and in repeat donors.

STUDY DESIGN AND METHODS

A retrospective analysis was performed of all incident hepatitis B virus (HBV), hepatitis C virus (HCV), and human immunodeficiency virus (HIV) infections in candidate, first-time, and repeat donors in the Netherlands during the period 2009 to 2013.

RESULTS

In total, 176,716 candidate donors, 144,226 first-time donations, and 4,143,455 repeat donations were screened for HBV, HCV, and HIV infection. Acute HBV infection was identified in the predonation sample of six candidate donors. One first-time donor, testing HIV-negative at predonation screening, tested positive for anti-HIV and HIV RNA in the first donation 29 days later. Among repeat donations we identified 15, one, and six incident HBV, HCV and HIV infections, respectively. The proportion of incident infections among candidate donors/first-time donations/repeat donations was for HBV, 3.40/0/0.36; for HCV, 0/0/0.02; and for HIV 0/0.69/0.14 per 100,000, respectively.

CONCLUSION

Predonation screening of candidate donors very likely causes a loss of donations, but it might prevent undetected window period donations. Further studies are necessary to determine the value of predonation screening as an additional safety measure.

Increasing prevalence of HDV/HBV infection over 15 years in France

BACKGROUND

In France, there are no consistent data estimating hepatitis delta virus (HDV) prevalence in the general population.

OBJECTIVES

To better characterize HDV/HBV infection and its trends over a 15-years period from 1997 to 2011, we used data retrieved from the National Epidemiological Donors database including viral and demographic characteristics of all French HBV infected blood donors.

STUDY DESIGN

Of the 39,911,011 donations collected over the 15 year-study-period, 6214 (1.56 in 10(4) donations) were confirmed positive for HBV from which 72.3% were tested for HDV antibodies (Ab). HDV viral load was performed using a real-time PCR assay on positive HDV Ab samples and HDV genotype determined for each positive viremic sample.

RESULTS

Among the 4492 HBV donations, 89 (1.98%) were HDV Ab positive. After being stable around 1.1% from 1997 to 2005, this rate has continuously increased to reach 6.5% in 2010, before declining to 0.85% in 2011. Of the 61 investigated HDV Ab positive individuals, 22.9% were viremic with a viral load ranging from 10(4) to 9.8 × 10(7) copies mL(-1). Genotyping revealed 12 HDV-1, 1 HDV-6 and 1 HDV-7 in accordance with the geographical origin of individuals.

CONCLUSION

Such a study gives unexpected features of HBV-HDV infection in the population of blood donors which is a priori, a healthy population. The increase of HDV prevalence mainly linked to migration of population from endemic countries, demonstrates that there is still no complete control of HBV infection and must encourage HBV vaccination campaigns and systematic screening for HDV in HBV-infected.