Surveillance of Transfusion Transmitted Infections

A surveillance system to collect standardised information about infections suspected to have been transmitted by transfusion was introduced in the UK (excluding Scotland) and the Republic of Ireland as a collaboration between the Health Protection Agency Centre for Infections and the transfusion services in October 1995. A similar collation of reports of cases investigated by Scottish blood centres has been in place in Scotland since October 1998.

Any possible incident of infection due to transfusion should be reported by the hospital where the transfusion took place, to the local blood centre. Each case reported is fully investigated to identify the infection and to confirm, or refute, that the blood transfusion may have been infectious. Blood centres in England, Wales and Northern Ireland are asked to report possible incidents of infection due to transfusion, of which they have been informed, to the NHSBT/HPA Epidemiology Unit. After the investigations are closed reported incidents are classified as a transfusion transmitted infection (TTI) according to the definition below.

Definition of a transfusion transmitted infection (TTI)

A report of an infection suspected to be due to transfusion was classified as a transfusion-transmitted infection if the following criteria were met at the end of the investigation:-

The recipient had evidence of infection post-transfusion, and there was no evidence of infection prior to transfusion and no evidence of an alternative source of infection, and either

At least one component received by the infected recipient was donated by a donor who had evidence of the same transmissible infection, or

At least one component received by the infected recipient was shown to contain the agent of infection.

Blood centres in Scotland report all incidents to the Microbiology Reference Unit of the Scottish National Blood Transfusion Service and the details and conclusion of each case are then provided to the NHSBT/HPA Epidemiology Unit.

It is important for the blood service to be informed about implicated transfusions so that investigations can be conducted. This is essential to prevent further transmission(s) by other components and/or by chronically infected donors, and to reveal any systematic errors or deficiencies in the blood service testing. Such investigations may involve microbiological testing of many donors and may take several months to complete (see Transfusion Microbiology pages of National Blood Service Hospitals & Science website).

Transfusion transmitted in 2010

Transfusion transmitted infections are rare. During 2010, 48 suspected TTI incidents were reported by blood centres and hospitals throughout the UK (Figure 5.1). These included cases where bacteria were cultured by the hospital from the patient or pack or patient samples were detected by the hospital to have virus markers post-transfusion. None were confirmed to be TTIs.

Some bacterial investigations were hampered either because leaking packs were returned to the blood service for testing or because packs were empty and discarded locally which led to the classification of two of the three undetermined cases in 2010 (see Box 2 for SHOT recommendations).

There were three bacterial near misses, two of these reported by the local issues department before the pack had been sent to a hospital.

There have been no confirmed transfusion-transmitted viral or parasitic infections since 2005.

For further information, please see our 2010 annual review entitled 'Safe supplies: Focusing on epidemiology'

Last reviewed: 4 October 2011