Transfusion-transmissible infection surveillance in Australia

Transfusion-transmissible infections surveillance reports

In 2011, Lifeblood and the Kirby Institute published a comprehensive surveillance report for transfusion-transmissible infections (TTIs) - Safe blood – a focus on education, epidemiology and testing. This report analysed surveillance data for the period 2005–2010 and was the preface to planned annual TTI surveillance reports, with the first annual report being published the following year in 2012.

Lifeblood regularly reviews and updates the donor interview and selection process, taking into consideration local and overseas research studies, international best practice, literature reviews and analysis of surveillance data such as that included in this report.

The 2019 transfusion-transmissible infections in Australia surveillance report has now been published and the major findings and Lifeblood responses are as follows:
 

1. Supporting the effectiveness of donor education and selection, the prevalence of transfusion‑transmissible infections is substantially lower among first‑time blood donors (13-28 times) than in the general population in 2018 and with the exception of potentially infectious syphilis shows a stable or declining trend over the period 2009-2018.

2. The prevalence of transfusion‑transmissible infections among first‑time donations was much higher than the prevalence among all donations, highlighting the importance of promoting donor education of potential new donors and ensuring first‑time donors read the pre‑donation information and understand the importance of ‘self‑deferral’.
 

Lifeblood focuses on education of all donors, particularly first- time donors, including providing a specific blood safety brochure highlighting the pivotal role of accuracy and honesty in answering the standard questionnaire. 

In accordance with state and territory laws, there are penalties including fines and imprisonment for anyone providing false or misleading information. 

While every effort is made to maximise donor retention, there is a fundamental requirement for continuing recruitment of new donors: firstly, to replace existing donors who can no longer donate (e.g. due to age and/or medical ineligibility) and secondly, to meet the growing demand for some blood products. 

Lifeblood considers the current proportion of first-time donations (6% in 2018) to be acceptable. Importantly, achieving a lower proportion of first-time donors whilst maintaining fresh blood product sufficiency and expanding plasma donations is a positive outcome.  

 

3. The incidence of newly acquired infection measured by the rate of incident donors is also much lower than results from specific at‑risk populations in Australia. This supports the general effectiveness of the donor questionnaire and specifically that repeat donors understand what constitutes ‘risk behaviour’ for acquiring transfusion‑transmissible infections.

 

4. Infective risk factors identified in blood donors with transfusion‑transmissible infections closely parallel those for the general population with no ‘unique’ risk factors identified to date among blood donors.

 

5. The non‑compliance rate among TTI-positive donors in 2018 was 20%, slightly lower than the 21% observed in 2017 but within the range of 15-25% observed in the last decade. The current rate highlights the importance of promoting donor education to ensure that the potential donors understand the importance of ‘self‑deferral’ to reduce the risk of collecting blood from a potentially infected donor whose infection may not be detected by testing.

 

6. While non‑compliance among positive donors has been routinely monitored since 2000, the rate among TTI test‑negative donors is more difficult to track.  

Results from a large national survey conducted in 2012-2013 showed a comparatively low rate of non-compliance (in the range 0.05 to 0.29%) among TTI test-negative donors for several sexual activity-based donor deferrals. The study included a multivariate analysis of factors influencing non-compliance, which suggested that the use of a computer-assisted structured interview (CASI) might lead to further improvement in the overall compliance rate.

 

Accordingly, Lifeblood has successfully piloted an electronic donor questionnaire for regular plasmapheresis donors at several plasma collection sites with plans to expand this process to all blood collection sites.

Non-compliance to screening questions remains an ongoing concern despite existing donor education initiatives targeting the importance of complete accuracy and honesty in answering the donor questionnaire. 

As noted, it is pleasing that the results of the national survey showed a comparatively low rate of non-compliance (in the range 0.05 to 0.29%) among TTI test-negative donors for several sexual activity-based donor deferrals. 

While it is reassuring that Australian rates are lower than comparable overseas rates, Lifeblood remains committed to seeking further improvement. 

One potential strategy to improve compliance is optimising the communication of the rationale underpinning deferral policies. Lifeblood continues to engage externally regarding initiatives to improve communication. Recommendations include optimising the use of social media, developing new education resources and refining current education resources.

Furthermore, the study identified a correlation with non-compliance and concerns over ‘privacy’ of disclosure, which might be partially alleviated by the use of a ‘computer-based’ donor questionnaire. As noted in the response to Q6 above, Lifeblood has implemented (at selected sites) an electronic donor questionnaire for regular plasmapheresis donors and plans to incrementally expand this to all collection sites.

 

7. The estimated residual risk of transmission for HIV, HCV, HBV, HTLV and syphilis in Australia is very low – less than one in one million per unit transfused. This supports the claim that Australia’s blood supply is among the safest worldwide in respect of transfusion‑transmissible infections for which testing is conducted. Despite this, there remains a minimal but real risk of transfusion‑transmissible infections that must be carefully considered before any transfusion.

 

8. Bacterial screening of 124 399 platelets identified 127 (0.10%) as confirmed positive. The majority of organisms identified were slow‑growing anaerobic skin flora not usually associated with post‑transfusion septic reactions. However, a minority of platelets grew clinically significant organisms that were likely to have been due to transient or occult bacteraemia in the donor and could have led to potentially serious septic transfusion reactions in the recipient. During 2018,no septic transfusion reactions were recorded due to platelets, however there was one non‑fatal transmission of Yersinia enterocolitica in a red cell component.

Reports of septic transfusion reactions associated with red cell transfusions in Australia are rare with the last recorded case occurring in 2012. Bacterial testing of red cell units occurs only where there is also a pooled platelet unit manufactured, constituting 58% of red cells manufactured. In this case, the pooled platelets associated with this donation were negative for bacteria. It is therefore likely that the donor had low level bacteraemia at the time of collection (possibly below the level of detection of the blood original cultures) and the bacteraemia in their donation was then amplified during storage as the contaminating organism,Y. enterocolitica is known to thrive at 4°C. Importantly, the risk of transfusion-transmitted bacterial infection from a red cell transfusion in Australia is very low, 0.29 per million compared with 2.74 per million prior to the introduction of platelet bacterial screening in 2008.

9. In addition to established transfusion‑transmissible infections, emerging infectious diseases continue to demand vigilant surveillance and risk assessment. Along with the ongoing risk from local dengue outbreaks and seasonal WNV outbreaks in Europe, outbreaks of Ebola virus, MERS CoV and Zika virus have also been closely monitored during 2018‑2019.    

 

Lifeblood maintains surveillance for emerging infections through close liaison with government communicable disease control units, CSL Behring, membership of international medical/infectious disease groups and active horizon scanning. 

Potential threats are regularly reviewed by Lifeblood Donor and Product Safety Committee and Clinical, Quality and Research Governance Committee, and risk assessment performed in the event that a threat is identified as a clear and present threat to the safety of the blood supply. Where appropriate, this will be performed in collaboration with CSL Behring (in their capacity as national plasma fractionator) and the Therapeutic Goods Administration.