Infectious transfusion risks: myth or reality?

Dear Sir,

In order to be able to discuss whether the risks of infection from transfusion are a myth or not, one should first of all define a myth. There are in fact numerous definitions for the noun “myth” [http://faculty.gvsu.edu/websterm/mythdefinitions.htm]. At least two of them tackle myth concepts from different perspectives which are relevant to transfusions. The first defines a myth as being “any fictitious story, or unscientific account, theory or belief” [http://www.sacc.to/glossary/glossary.htm#m], while the second one defines a myth as “a tale intended to be explanatory and that provides the grounds for a social practice, originally passed on via oral tradition, which offers an explanation of certain fundamental aspects of the world and of the society which created it or which acts as a vehicle for it” [http://en.wikipedia.org/wiki/Religion_and_mythology]. Based on the first definition, the initial answer to the question (“Is transmission of infection by transfusion a myth?”) is no, because the transmission of infectious agents via transfusion is not at all fictitious and has been fully proven both medically and scientifically, even though not all of its pathophysiological elements are fully understood. On the other hand, the myth of infectious transfusion risks is open to debate in the light of the second definition, which incorporates sociological/anthropological concepts. The second definition is also the context in which this contribution is made: the infectious risk associated with transfusions is “perceived” to differ according to the transfusion system and the medical culture in a give country.

The risk of transfusion-related infections dates back to the earliest days of large-scale transfusions: Plasmodia spp. and Treponema pallidum infections were recorded in 1911 and 1915. Measures have been taken for the last 50 years or so to safeguard the blood banking process and continue to be applied without cease. The transfusion-related transmission of human immunodeficiency virus (HIV) and hepatitis C virus (HCV) led to one of the greatest public health scandals in the late 20^th century in numerous countries. This state of affairs prompted the establishment of safety-oriented policies and strictly regulated quality standards. In France, HIV transmission was reduced by a factor of 1,000 within 25 years through additive and efficacious safety steps¹. Monitoring the residual risk of systematically screened viruses, i.e. HIV, HCV and hepatitis B virus, is a priority for transfusion systems and blood transfusion control agencies all over the world. Emerging/re-emerging agents are also the subject of active surveillance because some of them have definitely been proven to be transmissible by blood², such as the West Nile, Chikungunya, and Dengue viruses. Another major concern and, in some cases, almost an obsession is tracing the source of contamination of labile blood products, whether by bacteria or parasites. These latter include Plasmodia spp., the trypanosomes of Chagas disease and, foremost, Babesia spp., which are responsible for dozens of clinically severe or fatal cases each year in North America. Lastly, ever since prions were formally identified as being transmissible via blood³, and even before that, by virtue of a “precautionary principle”, measures to prevent Creutzfeld-Jakob disease have been implemented essentially worldwide, although only four transfusion cases has, as of yet, been identified (in the UK). Consequently, the following observation must be made: any viable agent which, at a given moment in its biological cycle, is present in blood either in a free or intracellular form can give rise to transfusion contamination.

Now let us consider the myths regarding the transmission of infectious agents via transfusions. With regards to the sociological aspect of the myth, empirically (as we are unaware of any specific investigations carried out regarding this topic), it is clear that the residual risks of an infectious nature relating to blood products are not very well known or classified by prescribing clinicians, in those instances in which they are not distorted or used by lobby groups for their own ends (as is the case with Jehovah’s Witnesses, whose website provides data that are more than 15 years out of date! [http://www.jw-media.org/aboutjw/article01.htm#accept]). Moreover, in 2012, it is still possible to find very approximate data being given (in all sincerity) to patients who need to receive a transfusion; the data presented are not, however, updated and refer to the situation about 2 decades ago. Likewise, outdated information continues to be published in educational documents and textbooks. It is in this respect that a myth does exist, as it is based on a statement, and the spread by word of mouth of information that has no scientific support and has not been verified scientifically.

On a completely different level, two other factors contribute to fuelling myths about the risk of pathogenic infectious agents being transmitted in blood. The first is the level of media coverage and high-profile legal proceedings which frequently place the viral risk back in the media spotlight. In profound contrast, while they are without doubt much more frequent in healthcare communities (whether in hospitals or not), nosocomial bacterial infections are relegated to second place compared to transfusion-related bacterial infections, and attract considerably less attention. Even more striking, transfusion-transmitted virus infections, which are far less likely than bacterial infections, attract proportionally more attention; although this situation has been minimised, the possibility of human error remains, as it does even in extremely safe activity such as civil aeronautics. The best possible analogy in our mind is the comparable discrepancy between the transfusion overload hazard, which, while not being infrequent, is probably too much of an ancillary issue to be considered noteworthy in transfusion practice, compared to accidents due to ABO incompatibility which, having become exceptional, trigger media reports.

The second factor contributing to the spread of the myth is what is known as “scientism”. Divorced from an overall view of medicine, bits of information build up regarding new viruses which can indeed be found in the blood and tissues of a substantial proportion of subjects, but have yet to be related to a human pathology. One of the most recent examples is the xenotropic murine leukaemia virus-related virus (XMRV): considerable questions on the pathogenicity of this virus in prostate cancer and chronic fatigue syndrome have been raised and yet no consensus has been reached on either of these issues nor indeed on whether XMRV actually poses a transfusion threat. Nevertheless, in the meantime, some transfusion organisations have already implemented preventive actions for this virus; these actions may be disproportionate to the actual pathogenicity or method of transmission of this virus. It is not easy to explain this high level of interest except for the need for a myth to have monsters. Can we rule out cynical exploitation of the topic by commercial companies seeking to introduce a diagnostic or detection test or a reduction procedure for these pathogens? But does this not bring us back to conspiracy theories? More prosaically, the fears regarding infectious agents, or rather the potential epidemics caused by them (such as the H1N1 flu), giving rise to millenarian fears which periodically flourish, have led to the concept and then to the implementation of the aforementioned “precautionary principle”, which has such strength nowadays that it has even been enacted in French legislation (passed in February 1995). Will the promises made by the promoters of procedures for reducing pathogens finally bring these myths to an end, or will a new outlet be found for continued fears concerning the transfusion of a red blood cell concentrate?

Thus, infectious agents are transmitted via blood, whether they are pathogens or whether they are only transmitted from one subject to the next as a new source of genetic information which is silent, as is the case with “hepatitis G virus”, transfusion-transmitted virus (TTV) and SEN virus. Nor is there any doubt that the viral risk is overplayed in the media compared to other transfusion risks. A quarter of a century after the dark years of transfusion, the factual and scientific aspects have not managed to establish themselves: an emotional dimension persists which gives rise to situations involving mechanisms sustaining major “myths”. One question that arises is whether emotion is more intense in this field of medicine than in others: when considering this issue, we hypothesised that blood recapitulates a large number of oppositions related to strengths and weaknesses (blood vehicles much more than just therapeutic compounds but also religious or magical feelings, inherited through the ages since the very beginning and the cosmogonies). This duality of strengths/weaknesses or more precisely guiltiness/innocence is linked to the concept of a “scapegoat”, first emphasised by Freud with the totems and the taboos, and then Durkheim, but brought to an apex by Girard, with his theory of “mimetism”, of “violence and the sacred”, of a “scapegoat”, culminating with an Apocalypse (standing for “Revelation”)^4,5. Girard has worked his whole life on his widely shared theory of the myth which extends Freud’s concept but opposes that of Levi-Strauss, who postulates that myths are words and words only (language); for Levi-Strauss, what matters is the organisation of this language, not the meaning. For Girard and the trend for myths to tend to the Apocalypse, is consubstantial of humanity. Jehovah’s witnesses, by fearing blood so much, confirm Girard’s theory on this example of transfusion; even if this religious group partly hides behind their fear of the transmission of infectious pathogens, their opposition is definitely bound to the myth of creation and the end of humanity.