Canadian Blood Services Responds to Possible New Blood Safety Threat
Canadian Blood Services takes the safety of the blood supply very seriously and we remain focused on the identification of potential threats to the blood supply whether they are blood borne pathogens or issues that may jeopardize the sufficiency of the supply of blood and blood products needed by patients.
Last fall, a report was published in the medical literature which suggested that there was an association between chronic fatigue syndrome (CFS) and the presence of a virus called xenotropic murine leukemia virus-related virus (XMRV). It was found that there was not only evidence of this virus in blood samples from American CFS patients but it was much more common than in samples from healthy individuals (67 per cent in CFS patients versus four per cent in healthy Americans).
Furthermore, these researchers could show that the virus from patient blood samples was able to infect cultured cell lines in the laboratory. What remains unknown was whether this virus is actually the cause of CFS in these patients. It was also unclear from this study whether there was actually live virus in healthy people as these researchers were only able to demonstrate a piece of the XMRV genome called ‘gag’ but not other parts of the virus that one would expect to find if the virus was intact and capable of being infectious. So, important questions remained unanswered, particularly with respect to risk to the blood system.
Studies conducted in early 2010 in the United Kingdom and in the Netherlands were unable to confirm the findings of the American study.
Nevertheless, the information was sufficiently important that Canadian Blood Services along with its sister organizations in the United States began to determine what should be done about protecting the blood supply.
Recognizing that we lack a proper test to look for XMRV, the first step is focused on test development. The second step will be to test enough North American blood donors to be able to understand whether XMRV actually is carried by healthy blood donors.
Until recently Canadian Blood Services has accepted blood donations from donors who report a history of CFS but are now well. Donors who are not well may not donate blood. However, given the lack of clarity around XMRV, we are changing the way we manage donors such that any donor who has a medical history of CFS will be indefinitely deferred from donating blood. Once we understand more about this issue, we will revisit this decision to determine whether the indefinite deferral is still warranted. We will be implementing this change in our clinics in the April/May time frame.
[1] Lombardi VC et al. Detection of an infectious retrovirus, XMRV, in the blood cells of patients with chronic fatigue syndrome. Science 2009; 326:585-9. [abstract]