Transfusion Transmitted Infections and Haemovigilance

Transfusion transmitted infection is infection in a recipient that is caused by a pathogen in a transfused component, confirmed by finding the same agent in the donor or the component and the absence of other likely sources. Haemovigilance is the system that detects, reports, investigates and learns from serious adverse reactions and events across the transfusion chain.

Important agents. Hepatitis B and C viruses, HIV, human T cell lymphotropic virus, syphilis, malaria (and other parasites), cytomegalovirus, parvovirus B19, hepatitis E virus, bacteria, and region-specific agents (dengue, West Nile virus, Chagas disease). Prion disease is a theoretical risk.

Residual risk. The risk is small where donor selection and laboratory testing are reliable, and arises mostly from donations during the window period before tests turn positive, from testing errors, and from agents that are not tested for. Risk is higher where testing capacity, voluntary unpaid donation or quality systems are limited, and where donors from family or replacement sources are used.

Malaria. In malaria endemic areas, donors may carry parasites without symptoms. Transfusion transmitted malaria is a real risk, and any fever in the weeks after transfusion should include a malaria test.

Clinical presentation. Fever, hepatitis, jaundice, new positive serology, seroconversion, anaemia and organ failure, with an incubation from days (malaria, bacteria) to weeks or months (hepatitis B and C, HIV).

Haemovigilance classification.

• Severity: grade 1 (non-severe), grade 2 (severe, requiring treatment or admission), grade 3 (life-threatening, requiring major intervention), grade 4 (death).

• Imputability to transfusion: excluded, unlikely, possible, probable, definite.

• Events: reactions, errors (wrong blood), near misses and incidents.

Differential diagnosis for a suspected transfusion transmitted infection.

• Infection acquired from other sources (community, hospital, sexual exposure, injections, surgery).

• Reactivation of latent infection in an immunosuppressed patient.

• Pre-existing infection missed at the time of transfusion.

• Drug or disease related fever and hepatitis.

Initial assessment. Timeline of transfusion and symptoms, all components given and their sources, the patient's baseline serology (stored pre-transfusion sample), risk exposures, and clinical findings.

Triggers for investigation. New hepatitis or seroconversion within an expected window after transfusion, unexplained fever after transfusion, or notification from the blood service that a donor has tested positive.

Immediate actions in order.

1. Stop any transfusion of the suspected component if still running, and clamp the line.

2. Assess the patient and treat any acute illness (sepsis, hepatitis, malaria) in the usual way.

3. Keep intravenous access as clinically needed.

4. Recheck identity and component details, and record the donation numbers of every unit given.

5. Inform the blood bank and the responsible clinician, who will notify the blood service so that the donor and co-components can be traced.

6. Do not discard samples: retain the pre-transfusion sample and take a new sample.

Investigations.

• Recipient: serology and nucleic acid testing for the suspected agent (hepatitis B, C, E, HIV, syphilis), malaria smear and rapid test, cultures if bacterial infection is suspected, liver function, full blood count and other tests as the picture requires, and a comparison with the stored pre-transfusion sample.

• Component and donor: the blood service quarantines co-components, tests the donor sample and recalls the donor for testing, and compares pathogen sequences between donor and recipient where possible.

• Lookback: identify all recipients of earlier donations from a donor who tests positive, and offer testing and treatment.

Definitive management. Treat the infection with the specific therapy for the agent: antimalarial treatment, antiviral therapy for hepatitis B and C and HIV (with specialist advice and counselling), antibiotics for syphilis and bacteria, and follow up of liver and viral markers. Offer counselling and partner notification where relevant.

Reporting.

• Report every suspected transfusion transmitted infection and every serious reaction or event to the hospital transfusion service and the haemovigilance system without delay, and report near misses and errors as well.

• A report includes: patient details (anonymised in national data), components and donation numbers, timeline, symptoms, tests, severity, imputability, actions taken and outcome.

• The blood service investigates the donor and components, and feeds back to the hospital.

• The hospital transfusion committee reviews each serious event, performs root cause analysis, and ensures corrective actions and staff learning.

Disclosure. Inform the patient, and the family where appropriate, honestly and promptly about any error or infection, with support and follow up.

Prevention.

• Selection of low risk donors, preferring voluntary unpaid donors, and careful screening of donor history.

• Mandatory laboratory testing for the main agents (HIV, hepatitis B and C, syphilis), with quality assurance, plus additional tests and malaria measures as local risk requires.

• Pathogen reduction where available, leucodepletion for cytomegalovirus risk reduction, and bacterial screening of platelets.

• Avoiding unnecessary transfusion, which is the most effective prevention, and keeping accurate traceability from donor to recipient.

• Learning from reports through regular audit and feedback.