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West Nile Virus Action Plan

Protecting the Blood System from West Nile Virus

In 2003, we began implementing extensive plans to reduce the risk of West Nile Virus (WNV) to the blood system. WNV testing has been performed on every blood donation since July 1, 2003 using an investigational test developed by Roche Diagnostics. The Action Plan gives us the flexibility to quickly respond when increased WNV risk is identified in any given community. It is re-evaluated over time and updated if required as new information and scientific evidence comes to light.

Overview of West Nile Virus Precautions

Mini-Pool Testing
We test every blood donation for WNV with the investigational Roche Diagnostics test using a testing procedure where six samples are mini-pooled prior to testing. If a mini-pool of blood samples tests positive for WNV, each unit is tested individually to identify the affected unit, which is then discarded. Any units which screen positive for WNV will be withdrawn and donors will be deferred from giving blood again for 56 days.

Single-unit Testing
Single unit testing will commence in a given health region when 1 positive donation is found through the mini-pool testing program or when recent human cases are identified in the population of that health region at a rate of greater than 1 in 1000 in rural areas or greater than1 in 2500 in urban areas.

Once single unit testing has begun in an identified population, single unit testing may also be initiated in adjacent health regions if it is deemed appropriate by our physicians and if system capacity permits.

Mini-Pool testing will continue on all donations where single unit testing is not being undertaken.

Single unit testing will cease in the affected health region after seven days. If additional donations screen positive for the virus and/or the number of human cases in the health region is above the population trigger during that timeframe, the seven day period will recommence.

If single unit testing was initiated because a positive donation was found through mini-pool testing, it will cease when no new positive donors are reported in that health region for a two week period. If single unit testing was initiated because of confirmed human cases of WNV in the local health region population, it will cease when new confirmed human cases, likely acquired locally in the population of that health region over the preceding two weeks, falls below the population trigger of 1 in 1,000 in rural areas or 1 in 2,500 in urban areas.

We are committed to providing Canadians with a safe and secure blood system. In the event of a large or widespread WNV outbreak, the triggers for implementing or discontinuing single unit testing in a health region may have to be modified since the system’s total capacity for single unit testing is limited and Canadian Blood Services must also ensure an adequate blood supply for those who need it. In such a situation of a widespread outbreak, Canadian Blood Services will also consider additional measures, such as suspending collections in areas of intense human activity while increasing collections in areas of no or less activity.

We work closely with The Canadian Public Health Agency and Héma-Quebec, as well as public health units and public health laboratories across the country, to ensure we are immediately aware of the presence of the virus in humans. In addition, we provide public health officials with notification of positive test results from our own donor screening test. Information about mosquitoes, birds and animals is also tracked, as this information often predicts the presence of the virus in the human population.

Cancelling Blood Donor Clinics in Severely Affected Areas
In the event that WNV activity is higher than expected, and the capacity for single-unit testing is exceeded, we may take the added precaution of stopping the collection of blood in severely affected areas. The decision to cancel any blood donor clinics will be made by reviewing all information available at the time. Public health officials, blood donors and the public will be given as much notice as possible. Clinic cancellations will involve well defined areas and will only occur if there is sufficient blood to meet hospital needs. We may ask the public to help us increase donations in areas of the country not experiencing outbreaks of WNV, in an effort to make up for reduced collections in heavily hit areas.

Deferring Ill Donors
People who indicate that they feel ill on the day of donation are deferred from donating. Donors who begin to feel ill after they donate are asked to contact us so their blood can be removed from the inventory. If any blood from these donors has been delivered to hospitals, the hospitals will be directed to discard it. If any of the affected blood has been transfused, the hospitals will be advised to notify the recipients’ physicians.

WNV in Recent Blood Donors
When public health authorities advise Canadian Blood Services of probable or confirmed cases of West Nile infection, we will check our records to determine if the individual made a recent blood donation. If this is the case, the units will be destroyed. If any of the blood from such a donation is already transfused, the recipients’ physicians will be informed so the appropriate follow-up work can be conducted. It is possible to have multiple recipients of a donor’s blood because the various blood components are separated and used in different ways for different people.

WNV in Recent Blood Recipients
If it is revealed that an individual who has been diagnosed as having a probable or confirmed case of West Nile infection received blood shortly before developing symptoms, all of the people who donated blood components received by that recipient, will be temporarily deferred. As well, other blood components remaining in the system that were donated by the donors will be withdrawn and discarded. It is common for blood recipients to receive multiple units of blood and each unit would be from a different donor. If any other blood components from the donors have been transfused into other recipients, the recipients’ physicians will be advised.

Informing Stakeholders and the Public
We collaborate with patient groups, hospitals, the health care community and other stakeholders to ensure that they are kept apprised of the risks to the blood system and the measures being taken to reduce them.

Ongoing Need for Donations

The best way for people to help is to donate blood generously at all times of the year to ensure patient needs are met and WNV safety measures can be implemented. Donors do not become infected with WNV by giving blood. Most mosquitoes do not carry WNV. Mosquito bites do not disqualify people from giving blood and every blood donation is tested for WNV. We assure Canadians that it is safe to donate blood. The greatest risk to the blood system will be if Canadians stop donating and there is a blood shortage.

Advice to Physicians and Patients

The benefits of blood transfusions outweigh the risk of WNV in life-saving situations. However, as the human population is affected by the virus, physicians and patients in affected areas should discuss the use of blood in non-emergency cases, such as elective surgeries. They may want to consider delaying the surgeries or using alternatives to blood transfusions, if applicable. Since each case is unique, this decision can only be made by an individual in consultation with his or her doctor.

At all times, we urge hospitals to use as little blood as is possible in each situation that they face. Since blood can never be 100 per cent safe, no person should ever be given a blood transfusion that is not considered medically necessary. All recipients of blood, who are capable of doing so, should be given the opportunity of providing informed consent before receiving blood or blood products. Canadian Blood Services is committed to providing the information Canadians need in order to make the best possible decisions.

Consultation with Stakeholders

We consults with many individuals and groups in order to formulate our action plan for West Nile Virus, including:

  • Canadian Blood Services’ Scientific and Research Advisory Committee (an independent group of international experts),

  • Canadian Blood Services’ Medical Directors located across the country (medical physicians associated with each Canadian Blood Services location),

  • Canadian Blood Services’ Transfusion Medicine Advisory Group (a group of independent Canadian medical experts),

  • Canadian Blood Services’ National Liaison Committee (a broad group of representatives from the Canadian hospital and medical communities, as well as donor and patient groups. The committee reports to the Canadian Blood Services Board of Directors),

  • Canadian Blood Services’ Safety, Science and Ethics Committee (a group of members of the Canadian Blood Services Board of Directors with expertise in medicine and ethics),

  • and the Provincial and Territorial Blood Contacts.

For additional information, please contact:
Ron Vezina
Director, Media Relations and External Communications
(613) 739-2144

West Nile Virus (WNV)
WNV Action Plan
WNV Q & As
WNV Resources
WNV News Releases & Statements

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