Current evidence highlights restrictive transfusion practice and its association with decreased morbidity and mortality. Serious adverse events can occur with transfusion, thus there must be careful consideration of the risk/benefit ratio when making the medical decision to transfuse.
While TRALI, TACO, bacterial contamination with associated sepsis, and hemolytic reactions are of grave concern and certainly demand our attention, we may forget that transfusion-transmitted disease (TTD) still remains a significant risk and can affect patients long after the transfusion episode. Our donor centers have done an excellent job in providing donor screening and testing that allows our blood supply to be one of the safest in the world. However, there are still potential threats and we should remain vigilant in our fight to reduce unnecessary transfusions and thus potential disease exposure.
In the 1980s and 1990s, most of our focus, as we all recall, was on HIV, hepatitis B and C. Current times have brought Ebola and Zika to the forefront and there are yet other infectious agents of which our donor centers are continually aware. These include malaria, babesiosis, dengue, chikungunya and the newest of the hepatidites, hepatitis E. Donor screening and potentially, pathogen inactivation, may help to eliminate or at least reduce some of these infectious agents. It is incumbent upon us as healthcare providers to be familiar with these diseases and remember that unnecessary transfusions place our patients at risk. These infections are associated with serious illness, both acute and chronic as well as potential mortality particularly in immune- suppressed patients.
The global burden of malaria is huge and the number of cases reported in the U.S. is increasing. Malaria is caused by the parasite, genus Plasmodium, transferred via mosquitos and represents an intra-erythrocytic infection, thus, the risk of transfusion-transmitted malarial infection is possible, particularly with RBCs and has been reported. There is currently no FDA-approved screening test for malaria and therefore, blood suppliers rely on screening questionnaires that identify donors who have travelled to endemic regions. Subsequent deferral is done if indicated.
Babesiosis is another intra-erythrocytic infection, tick-borne and caused by Babesia microti. One hundred sixty transfusion-transmitted cases have been reported as of 2014, 75 percent of these since 2000. As with malaria, there is no licensed test for donor screening and donor travel history is key. In babesia-endemic regions of the U.S., there is a test available under IND. The 2014 AABB bulletin provides excellent information for transfusion services and donor centers on this topic.
Transfusion-transmitted malarial or babesia can be treated and pathogen inactivation (PI) methodology can eliminate these organisms. PI, however, is not currently approved for RBC components, only platelets and plasma.
Dengue is an enveloped single stranded RNA virus that causes infection in over 50 million people per year. It is transmitted via the Aedes mosquito. A NAT has been developed but is not yet licensed in the U.S. Dengue can cause serious clinical hemorrhagic fever and there is no specific therapy other than supportive. PI can eliminate this agent. A recent 2016 AABB bulletin discusses dengue in more depth.
Chikungunya is another Aedes mosquito-borne arbovirus. Although no documented cases of TTD have been reported, the likelihood must be considered given its similarity to dengue. NAT-positive donors have been identified outside of the U.S. No licensed tests are presently available. Interestingly, there is current research into a vaccine that could aid in reducing the incidence of this infection. PI methods are effective in eliminating this virus.
The newest hepatitis virus of concern is HEV, a small non-enveloped RNA virus which tends to be transmitted via contaminated food and water much like HAV. TT-HEV has been reported. Patient NAT screening for donors might be useful to prevent this infection if, indeed, this virus appears going forward to represent a significant threat to the blood supply.
Current blood safety is outstanding and our donor centers continue to be vigilant in understanding and preventing newly-identified infectious agents. There still remains a risk of TTD and, as mentioned, this should be seriously considered when discussing the possible transfusion therapies with our patients and our colleagues. Unless absolutely necessary and life-saving, the best transfusion is the one not given.
- Schmidt M et al. Transfus Med Hemother. 2014 Feb; 41(1): 10–17. doi: 1159/000358017
- Weaver SC et al. N Engl J Med 2015 Mar 26; 372(13): 1231-1239 doi: 10.1056/NEJMra1406035
- AABB Bulletin #14-05, aabb.org
- AABB Bulletin #16-04, aabb.org
- AABB Technical Manual, 18th edition, 2014. Chapter 8
- Stramer SL et al. Transfusion 2016; 56: 481-488 http://dx.doi.org/10.1111/trf.13355
Author: Carolyn Burns, M.D.