London Blood Donors Research Articles

Seroprevalence of SARS-CoV-2 among Blood Donors and Changes after Introduction of Public Health and Social Measures, London, UK.

We describe results of testing blood donors in London, UK, for severe acute respiratory disease coronavirus 2 (SARS-CoV-2) IgG before and after lockdown measures. Anonymized samples from donors 17–69 years of age were tested using 3 assays: Euroimmun IgG, Abbott IgG, and an immunoglobulin receptor-binding domain assay developed by Public Health England. Seroprevalence increased from 3.0% prelockdown (week 13, beginning March 23, 2020) to 10.4% during lockdown (weeks 15–16) and 12.3% postlockdown (week 18) by the Abbott assay. Estimates were 2.9% prelockdown, 9.9% during lockdown, and 13.0% postlockdown by the Euroimmun assay and 3.5% prelockdown, 11.8% during lockdown, and 14.1% postlockdown by the receptor-binding domain assay. By early May 2020, nearly 1 in 7 donors had evidence of past SARS-CoV-2 infection. Combining results from the Abbott and Euroimmun assays increased seroprevalence by 1.6%, 2.3%, and 0.6% at the 3 timepoints compared with Euroimmun alone, demonstrating the value of using multiple assays.

The prevalence of chromosomally integrated human herpesvirus 6 genomes in the blood of UK blood donors

A lesser-recognized form of human herpesvirus 6 (HHV-6) persistence is integration of the viral genome in a host chromosome and high viral copy numbers in blood or sera are characteristic of this phenomenon. A cross-sectional study was performed to determine the frequency of high HHV-6 viral loads in whole blood (>6 log(10) copies/ml) in a population of blood donors in London, UK. Blood samples from 500 anonymized blood donors were collected from one donation center, DNA extracted, and quantitative realtime PCR used to measure viral load. Four samples (0.8%) were found to have high viral copy numbers of HHV-6 (median 6.7 log(10) copies/ml; range 6.5- 6.9 log(10) copies/ml). Cellular DNA was also quantitated using qRT-PCR for beta-globin. By comparing these two results, we calculated that there were between two and five copies of HHV-6 present per cell in these four donors. The median viral load detected in plasma from the four individuals was 3.8 log(10) copies/ml (range 3.5-4.0 log(10) copies/ml). All samples were HHV-6 variant B. In addition, a retrospective analysis of all diagnostic blood samples performed for HHV-6 in our center showed a prevalence of 2.9% of high viral loads characteristic of integration. In conclusion, high viral copy numbers of HHV-6, representing a population of viral integration, is detected in 0.8% of UK blood donors. The presence of high HHV-6 viral loads in healthy normal individuals reiterates the need to consider the confounding effect of HHV-6 viral integration in any laboratory diagnosis of HHV-6 infection.

Seroprevalence of herpes simplex virus type 2 in multiple sclerosis

It has been proposed that multiple sclerosis (MS) might be a sexually transmitted disorder. There is evidence that seropositivity to herpes simplex virus type 2 (HSV-2) correlates well with the number of sexual partners. Accordingly, a raised overall HSV-2 seroprevalence in MS would lend support to this theory. Serum from 497 UK subjects with clinically definite MS was tested for antibodies to HSV-2 and compared with matched historical controls from within and outside London, blood donors and genito-urinary medicine (GUM) clinics. The unadjusted MS seropositivity rate was 14%. HSV-2 seroprevalence in MS patients aged 35-64 years was significantly higher overall compared with a non-London general population in an unadjusted comparison. HSV-2 seroprevalence in London MS patients compared with London blood donors was significantly greater irrespective of age, but the MS seropositive rate was lower than GUM clinic attenders. In a logistic regression analysis, increased age, female sex and MS diagnosis all independently increased the odds of seropositivity after adjustment for each other. It is concluded that there is increased likelihood of HSV-2 exposure in patients with MS and this may indicate a higher than average number of partners.

Legionella contamination of waterlines?

Objectives To determine the prevalence of legionellae in dental unit waterlines (DUWL) in general dental practices in London and rural Northern Ireland and whether the organism occurs at a high enough frequency and magnitude in DUWL to represent a threat to dentists' health. Materials and method Two hundred and sixty six (166 London, 100 Northern Ireland) randomly selected dental surgeries were recruited. Standardised 250 ml water samples were taken from the DUWL and 1 litre samples from the surgery cold water tap to measure the prevalence of legionellae. The dentists provided a blood sample for legionella serology. Results The prevalence of legionellae was very low (0.37%). Legionellae were not isolated from DUWL or surgery basin taps in Northern Ireland. Legionella spp were isolated from the DUWL and surgery basin of one practice in London and from the cold water supply of a further three practices. The prevalence of Legionella pneumophila antibodies was less than that seen in a comparable group of London blood donors. Conclusion The risk to dentists' health from potential exposure to legionellae in this cohort of dentists was very low and this was confirmed by the very low seroprevalence and antibody titres to legionella detected in the dentists.

Prevalence of legionella waterline contamination and Legionella pneumophila antibodies in general dental practitioners in London and rural Northern Ireland.

To determine the prevalence of legionellae in dental unit waterlines (DUWL) in general dental practices in London and rural Northern Ireland and whether the organism occurs at a high enough frequency and magnitude in DUWL to represent a threat to dentists' health. Two hundred and sixty six (166 London, 100 Northern Ireland) randomly selected dental surgeries were recruited. Standardised 250 ml water samples were taken from the DUWL and 1 litre samples from the surgery cold water tap to measure the prevalence of legionellae. The dentists provided a blood sample for legionella serology. The prevalence of legionellae was very low (0.37%). Legionellae were not isolated from DUWL or surgery basin taps in Northern Ireland. Legionella spp were isolated from the DUWL and surgery basin of one practice in London and from the cold water supply of a further three practices. The prevalence of Legionella pneumophila antibodies was less than that seen in a comparable group of London blood donors. The risk to dentists' health from potential exposure to legionellae in this cohort of dentists was very low and this was confirmed by the very low seroprevalence and antibody titres to legionella detected in the dentists.

An evidence based approach to testing for antibody to herpes simplex virus type 2

Objectives: To establish whether a simple risk scoring system, based on limited information, can reflect the variation in HSV-2 prevalence in a population, and whether a common system can be...

Does anti-HBc reactivity reflect 'lifestyle' risk in north London blood donors?

To determine whether antibody to hepatitis B core (anti-HBc) reactivity, as a marker of hepatitis B virus infection, reflects a 'lifestyle' risk in donors in North London, we have obtained detailed histories from donors with various manifestations of HBV infection. Interviews based on a standardised questionnaire were conducted with 70 donors confirmed to be anti-HBc reactive. Comparison with controls (known to be anti-HBc-negative) and donors reactive for anti-hepatitis-C virus showed that current donor strategies are effective; in our area, reactivity for anti-HBc is not associated with a lifestyle risk for those donors who are unreactive in current mandatory screening tests. Blood from donors positive for both anti-HBc and anti-HBs should be considered suitable for transfusion purposes. This is consistent with the practice of accepting blood from naturally immune donors for preparation of hepatitis B immunoglobulin.

Does Anti-HBc Reactivity Reflect 'Lifestyle' Risk in North London Blood Donors?

Does Anti-HBc Reactivity Reflect 'Lifestyle' Risk in North London Blood Donors?

Relationship between antibodies to herpes simplex virus (HSV) and symptoms of HSV infection.

To determine the relationship between antibodies to herpes simplex virus (HSV) types 1 and 2 and diagnosis of orolabial and genital herpes, a cross-sectional survey was done among 869 sexually transmitted disease clinic attendees and 1594 blood donors in London. Among clinic attenders, the prevalence of HSV-1 infection was 59.5% and that of HSV-2 infection was 22.7%, and among blood donors the prevalence was 44.6% and 7.6%, respectively. The sensitivity and specificity of a diagnosis of oral herpes for the presence of HSV-1 antibody was almost identical in the 2 groups (clinic attendees: sensitivity, 33.1%, and specificity, 91.4%; blood donors: sensitivity, 32.3%, and specificity, 94.3%). A diagnosis of genital herpes was less sensitive for antibody for HSV-2 among donors than among clinic attenders (P < .001); however, the specificity was similar in the 2 populations (clinic attendees: sensitivity, 32.1%, and specificity, 96.6%; blood donors: sensitivity, 17.5%, and specificity, 99.5%). False-positive clinical histories were also relatively common (clinic attenders, 12%; donors, 6%). The sensitivity of the diagnosis of genital herpes would be improved if accurate serologic assays for detection of HSV type-specific antibodies were more widely available.

Behavioural risk factors for HIV infection amongst blood donors in London

This paper compares the prevalence of risk factors for sexual acquisition of human immunodeficiency virus infection (HIV-1) among blood donors with the risk in the general population. Sexual behaviour data collected as part of a cross-sectional survey of central London blood donors were compared, after indirect standardization for age and sex, with those collected among Greater London participants of the National Survey of Sexual Attitudes and Lifestyles (NATSSAL). Overall, male blood donors had lower risk sexual lifestyles than age-matched NATSSAL participants in that they had had fewer lifetime female sexual partners, were more likely to have had first sexual intercourse after 16 years and were less likely to have had a homosexual partner. Men who have had sex with men since 1977 were asked not to donate blood. Despite this, 3.6% of male donors had had some sexual experience with another man and 1.9% had had sexual intercourse with at least one male partner. In contrast, female donors had had more sexual partners, were more likely to have had first sexual intercourse before 16 years and had probable higher rates of sexually transmitted disease (STD) clinic attendance than NATSSAL participants, explained by the much higher proportion of single rather than married female blood donors at each age. In conclusion, male donors had lower risk sexual lifestyles than age-matched NATSSAL participants, although even low levels of homosexual contact give some cause for concern. Female donors appeared to have higher risk sexual lifestyles than the general population because a much higher proportion of the female blood donors were single. The results provide important insights for those defining blood donor referral criteria.

Hepatitis B markers in West Yorkshire firemen.

Firemen have been considered at occupational risk of hepatitis (HBV) infection, but proof is lacking. The aim of this study was to assess the degree of risk by determining the prevalence of serological markers of past infection with HBV in members of the West Yorkshire Fire Service. Sera from 173 firemen, 9.3% of the brigade, were tested for antibodies to HBV surface antigen and to core antigen. Those containing anti-HBs greater than or equal to 10 IU/L or anti-core antibody, were also tested for antibody to HBe antigen. The presence of more than one marker was used to define past infection. One sample satisfied this criterion, giving a prevalence rate of 0.6%. This compares with a rate of 1% in London blood donors. We conclude that the group shows no evidence of having been at increased risk of HBV infection. A comprehensive vaccination policy for firemen might be questionable.

Serum alanine aminotransferase (ALT) and gamma-glutamyltransferase (gamma-GT) activities in north London blood donors.

Serum alanine aminotransferase (ALT) and gamma-glutamyltransferase (gamma-GT) activities were measured in over 2000 north London blood donors. The results were compared with those from the United States. The percentage of the total donor population with ALT activities above 40 IU/l in 1986 was greater than that found in our earlier studies in 1973 and 1982 (4.6% compared with 2.8% and 3.1%, respectively). There was a noticeable difference in the ALT distribution between male and female donors: mean +2.25 SD for male donors was 55.3 IU/l, while that for female donors was 30.8 IU/l at 37 degrees C. In stability studies the optimal temperature for short term storage (10 days) was 4 degrees C (6.4% loss of activity after 10 days). Surprisingly, storage at lower temperatures (-35 degrees C and -80 degrees C) resulted in greater loss of activity.

BK virus specific IgM responses in cord sera, young children and healthy adults detected by RIA.

An IgM capture solid-phase radioimmunoassay (MACRIA) for BK virus (BKV) specific IgM is described. This test was found to be more sensitive in detecting BKV specific IgM than both haemagglutination inhibition and immune electron microscopy with serum fractions from sucrose density gradients. The use of this specific assay allowed large numbers of sera to be examined with ease so that the distribution of BKV specific IgM in different populations could be studied more fully. BKV specific IgM was detected in 11/300 sera from London blood donors, in 24/114 sera from children aged between 2 and 11 years admitted to a paediatric unit and 14/79 sera taken from children aged between 2 and 5 years for the investigation of anti-streptolysin 0 titres. BKV specific IgM was not detected in 404 cord sera examined to investigate the transplacental transmission of BK virus.

Prevalence of antichlamydial antibody in London blood donors.

The prevalence of type-specific antichlamydial antibody in a population of blood donors in London was studied using a microimmunofluorescence test. Twenty-six (17%) of 150 women and 38 (26%) of 150 men had antichlamydial antibody (IgG at greater than or equal to 1/16 or IgM greater than or equal to 1/8 or both). Of these, five (3%) women had one (0.75%) man had this antibody directed against Chlamydia trachomatis serotypes D-K, responsible for genital infections, and one man had antibody to Chlamydia psittaci agents. The remaining 57 men and women had antibody against an atypical chlamydial isolate designated Chlamydia IOL-207, which is iodine-negative and serologically distinct from both C trachomatis and C psittaci. The nature and location of infection by this agent are obscure. The results of this study suggest that the prevalence of sexually transmitted infection with C trachomatis serotypes D-K in a normal adult population in London is very low.

The prevalence of hepatitis-B antigen (HB S Ag) and its antibody (Anti-HB S) among London hemophiliacs and blood donors from London and two tropical areas.

The prevalence of hepatitis-B antigen (HB s AG) and its antibody (anti-HBs) among 49 London hemophiliacs was compared with that among women attending an antenatal clinic and healthy blood donors from London and from two parts of the tropics (Mauritius and Zambia). The prevalence of HBsAG and anti-HBs was low in antenatal patients, London blood donors and blood donors from Mauritius. However, a high proportion of hemophiliacs (59%) were anti-HBs positive, this being comparable with Zambian blood donors (53%), although anti-HBs titers in hemophiliacs were much higher (GMT 1:342) than in Zambian blood donors (GMT 1:36). In contrast, HBsAG was detected in 29 of 250 (12%) Zambian donors but in only 3 of 49 (6%) hemophiliacs. Clinically overt hepatitis occurred in only two hemophiliacs. However, the presence of HBsAG-specific IgM in 7 of 29 (24%) anti-HBs-positive hemophiliacs suggests that a proportion of these patients recently experienced subclinical infection by hepatitis-B virus, Anti-HBs-positive hemophiliacs received a significantly higher number of- cryoprecipitate units than did those without anti-HBs(P less than 0.01). Five of seven hemophiliacs with high titers of anti-HBs (greater than 1:4,096) showed a decline in titer after 1972 which may have been associated with the introduction of screening of cryoprecipitate for HBsAG.