CANADIAN BLOOD SERVICES ANNOUNCES VOLUNTARY WITHDRAWAL OF SASKATCHEWAN BLOOD
Ottawa, September 3, 2003 – In response to a significant increase over the past week in the number of people in Saskatchewan believed to have West Nile Virus (WNV), Canadian Blood Services has announced a precautionary, voluntary withdrawal of all blood components collected in that province since August 4, 2003. Additionally, beginning with collections made yesterday, Canadian Blood Services has begun to change the method it is using to test Saskatchewan blood donations for the virus, switching from testing blood samples in pools of six, to testing each individual blood sample.
“Although the risk of WNV infection to blood recipients has been considered extremely low since we began using our new test in July, we are moving forward with this plan to further ensure the safety of the blood system,” said Dr. Graham Sher, Chief Executive Officer, Canadian Blood Services. “Our job is to continually review the environment and determine if we are doing everything we can to reduce the risk of infection to the people who receive blood. We have determined that right now we have the capacity to replace the roughly 4,000 units of blood that were collected in Saskatchewan after August 4; therefore, we should do it. It is also reasonable to think that our test may be better able to detect low levels of the virus if it is used on single samples rather than pooled groups. Although there are no scientific data to support this prediction, we believe these actions will add another layer of safety until the sensitivity of our new test is more clearly determined later this year.”
Canadian Blood Services is requesting that hospitals across Canada isolate and hold blood products collected in Saskatchewan between August 4 and August 31, 2003, until they have been replaced either with blood collected prior to June 1, 2003 (frozen products) or with blood collected in other parts of the country. The replacement effort has already begun.
The number of human cases of WNV in Saskatchewan has risen significantly over the past week, making it the clear ‘hot spot’ in Canada for WNV. On August 25, 2003 Health Canada’s Web site listed 28 probable or confirmed human WNV cases in Saskatchewan; that number increased to 43 on August 29, 2003. On September 2, 2003, the Saskatchewan government Web site listed 69 probable or confirmed human WNV cases. Furthermore, eight of the 12 blood donations identified as containing WNV since Canadian Blood Services began testing all units of blood for the virus in July, were from Saskatchewan blood donors. No other province has recorded such a rapid increase or such a concentration of cases in its population. As of September 2, 2003, the number of human cases in Saskatchewan was 70 per one million people, which is significantly higher than Alberta (the province with the second highest number of cases), which had 15 per million.
“There are two key factors that have influenced our decision. First, as we said when we introduced our new test, we don’t know its precise sensitivity because this is the first year it is being used. It seems reasonable to think that it might be better able to detect low levels of the virus in one small sample than in a larger pool that would dilute the virus. As part of this initiative, we are going to take part in a North American study that will tell us whether or not ‘single-unit’ testing rather than ‘mini-pool’ testing is safer. It is entirely possible we will learn that ‘single-unit’ testing does not increase the test’s ability to detect WNV, but right now we don’t know that, so we think the best thing to do is to try this so we can find out,” said Dr. Sher.
“The other factor is that we are doing this because, at this particular point in time, we can. Ironically, because the Canadian public responded extremely generously to our recent call for blood donors due to the Ontario blackout, we have a larger-than-normal inventory. The blackout had forced us to shut down many of our Ontario clinics and prevented us from being able to collect about 3,000 units of blood. But thanks to the generosity of Canadians we have made up those 3,000 units and in fact, have a strong inventory today. Because Saskatchewan is a small province in terms of its blood requirements, we can replace the roughly 4,000 units of blood that were collected there over the past four weeks. Also, because the number of units collected there is relatively small, we have the capacity to test each individual unit over the next few weeks. If we were talking about a larger province, we would not be able to do this because we wouldn’t have the adequate equipment or manpower,” added Dr. Sher. “We do not expect to be extending these measures to any other province because we will not have the capacity to do so.”
Similar initiatives are being undertaken in the U.S. as various WNV ‘hot spots’ are emerging there. Canadian Blood Services will share its data with the U.S. to further current knowledge about WNV and the tests available to detect it.
After the 2003 WNV outbreak subsides, Canadian Blood Services will switch back to ‘mini-pool’ testing of Saskatchewan blood donations.
“Meanwhile, we ask people to continue to donate to help ensure everyone receives the blood they need,” said Dr. Sher. “If you have an appointment to donate already, please keep it; and if you have never donated before, now would be a great time to start.”
Canadian Blood Services will continue to work closely with Health Canada, Héma-Quebec and public health officials to investigate all reported probable and confirmed cases of WNV to determine if they involve recent blood donors or recipients.
Canadian Blood Services is a national, not-for-profit charitable organization that manages the blood supply in all provinces and territories outside of Quebec and operates the country’s Unrelated Bone Marrow Donor registry. Canadian Blood Services operates 40 permanent collection sites and more than 14,000 donor clinics annually. For more information, please visit our Web site at www.bloodservices.ca.
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