Research and analysis

HPR volume 19 issue 7: news (31 July 2025)

Updated 31 July 2025

Transfusion transmitted infections (UK): 2024 annual report in summary

Suspected transfusion transmitted infections (TTIs) should be reported promptly to the Blood Service for investigation, particularly when no other cause can be identified, to ensure that other components can be recalled preventing further harm. TTIs remain extremely rare in the UK due to risk reduction strategies including donor selection and rigorous testing of blood donations. All suspected TTIs investigated by the UK blood services are reported to the joint NHS Blood and Transplant (NHSBT) and UKHSA Epidemiology Unit for monitoring and form part of the Serious Hazards of Transfusion (SHOT) haemovigilance scheme.

This news report summarises the findings of the 2024 Annual SHOT Report which has been published on the SHOT website.

During 2024, the UK blood services investigated 118 suspected bacterial and 18 suspected viral incidents. There were no confirmed transmissions reported. Most suspected bacterial cases were concluded to be either a post-transfusion reaction or related to the patient’s underlying condition including all cases where patient blood cultures were positive, with no evidence of bacteria in the implicated or associated products or in the recipient. Two bacterial near miss incidents were reported (both Staphylococcus aureus). Since 2011, all four UK Blood Services have used the BacT/ALERT system for bacterial screening which has been successful in reducing the risk of bacterial TTI, together with diversion and arm cleansing. The last confirmed bacterial TTI – a Staphylococcus aureus – was reported in 2015.

Of the viral investigations, 15 were concluded as not transmissions, but one possible hepatitis C (HCV) transmission was identified from a transfusion in 1993. This was possibly a window period donation since the donor tested negative for anti-HCV antibodies, but HCV nucleic acid testing (NAT) was not available at the time of testing. Two investigations (both parvovirus B19) are still pending. Viral transmissions are extremely rare in the UK, with only 33 confirmed transfusion-transmitted viral infections documented in the UK since 1996. Among these, hepatitis B (HBV) (n=11) and hepatitis E (HEV) (n=12) were the most commonly reported proven viral TTI. Since 2022, hepatitis B core antibody (anti-HBc) screening has been undertaken to reduce the risk of HBV transmission from donors with occult HBV (OBI). For HEV, all except 2 transmissions were reported before the HEV RNA screening was introduced in April 2017 in the UK.

Lookback investigations

Lookback investigations are initiated when repeat donors are found to be newly positive for a marker of infection, either through donor seroconversion, post-donation information or introduction of new test. Following the introduction of anti-HBc screening in 2022, lookback investigations were initiated for some donors.  All anti-HBc repeat reactive donations are discarded and confirmatory HBV deoxyribonucleic acid (DNA) testing is done on individual donation samples.

During 2024, NHSBT initiated investigations prompted by 11 donors in England with newly detected markers of infection known to have previously donated.  Archive samples were available for testing for nine donors (1 Parvovirus B19, 1 Hepatitis A infection, 1 HIV infection, 4 OBI and 2 syphilis), but for two donors the most recent negative donation had been given more than three years ago and therefore no archive was available for testing (1 HCV and 1 HEV).

Investigations involved 17 previous donations, with 22 of 29 components issued known to be transfused. Of the 22 recipients identified, 7 were alive and 4 were tested with none found to have evidence of transmission. Information from follow-up of recipients for the HCV, HEV and 1 OBI investigation is awaited.

Further information about these cases is available in the TTI chapter of the annual SHOT report.

Key messages from the new SHOT report are as follows:

1. All suspected TTI should be reported for investigation, even though confirmed or probable TTI are rare
2. Hospitals are encouraged to report suspected TTI when there are no other obvious risks
3. The consultant microbiologist, virologist, and/or other infectious disease experts should be consulted to confirm the diagnosis of a suspected TTI
4. Once confirmed, the suspected TTI should be reported to the appropriate UK Blood Service for further investigation

Further information about UK TTI surveillance is available from the NHSBT and UKHSA Epidemiology Unit: epidemiology@nhsbt.nhs.uk

Salmonella cluster associated with eggshell membrane food supplements

UKHSA, alongside the Food Standards Agency (FSA) and Food Standards Scotland (FSS), are supporting Public Health Scotland who are leading an investigation into a cluster of multi-drug resistant Salmonella associated with consumption of an eggshell membrane food supplement sold online.

These supplements are typically taken by people following fitness regimes and by older adults, as they claim to have benefits for joint health and longevity. However, elderly adults and those with existing health conditions face a higher risk of developing severe or invasive salmonellosis.

The FSA has recalled the eggshell membrane food supplement product, see Update 2 - Orgenism recalls Eggshell Membrane Capsules because of contamination with Salmonella.

Several serovars of Salmonella have been detected in the eggshell membrane food supplement, including Salmonella Enteritidis, S. Othmarschen and S. Livingston. Reference laboratory testing indicates a multi-drug resistant profile for the S. Enteritidis including resistance to third generation cephalosporins (bla CTX-M-14), fluoroquinolones, tetracycline, fosfomycin, and colistin.  

No antimicrobial resistance has been detected in the S. Othmarschen isolates. For S. Livingston isolates, no antimicrobial resistance beyond intrinsic resistance to Aminoglycosides was detected. In addition, multiple ESBL-producing Enterobacterales were also isolated from samples of the product including E.coli, Klebsiella spp., and Acinetobacter spp.

Four human cases associated with these eggshell membrane food supplements have been identified to date, 2 cases in Scotland (one S. Othmarschen and one S. Enteritidis) and 2 cases in England (both S. Enteritidis).

The guidance to the public remains unchanged – symptomatic members of the public wishing to be tested should seek healthcare in the usual way (via their GP, NHS 111 or A&E department). If individuals complain of severe illness, direct to A&E in the first instance.

Further FSA related advice is available: Salmonella: What you can do to reduce the risk of becoming ill due to Salmonella

Infection reports in this issue

Laboratory confirmed cases of invasive meningococcal infection in England: January to March 2025

Common animal-associated infections in England: 2024

Vaccine coverage reports

RSV immunisation for older adults and pregnant women in England: monthly reports

Shingles vaccine uptake report (adults eligible from September 2024 to February 2025 and vaccinated to the end of April 2025): England