West Nile Virus


1. How is the West Nile Virus spread?
Mosquitoes catch the West Nile Virus when they feed on the blood of an infected bird. These infected mosquitoes can subsequently transmit the virus to those animals and humans that they bite in order to feed. The virus then spreads throughout the blood and can cause an infection. There have been some confirmed cases of the West Nile Virus being transmitted by means of blood transfusions and organ transplants in Canada and the United States.

2. What are the symptoms of West Nile Virus (WNV) infection?
Most infected people have no symptoms. One out of five people will experience a minor infection and only one out of 150 will develop a serious illness affecting the brain and requiring hospitalization. When infection does lead to the disease, symptoms generally appear 4 to 8 days after initial contact with the source of the infection. The disease itself lasts about 7 days.

3. Is there a treatment for the infection?
There is no specific treatment for the infection caused by the West Nile Virus . Severe cases require hospitalization.

4. Can a person catch the West Nile Virus by giving blood?
No. Donors cannot contract the West Nile Virus by giving blood. All materials used to collect blood are sterile and disposed of after use. It is important that all Québeckers continue to donate blood generously at blood drives organized throughout the province.

5. Is there a test that can identify the presence of the West Nile Virus in donated blood?
Héma-Québec has a commercial test, which was developed by Roche Diagnostics, to detect the presence of the West Nile Virus (WNV) in donated blood. Since June 25, all donated blood taken was analysed with this test, and which will replace the in-house test developed by Héma-Québec’s R&D division. Since June 18, all blood components produced by Héma-Québec have been tested for the presence of the WNV using this in-house test.

6. What happens when people exhibiting symptoms of West Nile Virus infection offer to donate blood?
When people present symptoms of West Nile Virus infection, it is possible that they are infected. As a result, since Héma-Québec already excludes potential donors showing symptoms of infection from donating, these people will not be permitted to give blood.
Like all the other blood providers in North America, Héma-Québec is adding to the blood giving process a step related to this new virus by asking the donor if he in the last 7 days he has had fever and headache. If the answer is positive, the donor will be excluded for 55 days.

7. What will be done if a person who has probably been infected has donated blood?
Héma-Québec will:

  • quarantine the transfusion products containing the blood of that person;
  • quarantine all blood products destined for further processing;
  • remove that person from the donor list.

If more thorough testing reveals that the person is not infected, the quarantine will be lifted and the person may begin to again give blood, unless other reasons require his/her exclusion from the donor list.

8. What will be done if an infected person has given blood?
Héma-Québec will:

  • withdraw all transfusion products containing blood from the infected person;
  • withdraw all blood products destined for further processing;
    remove that person from the donor list for a period of eight weeks following the probable initial date of infection.

The extent and seriousness of symptoms vary greatly from one person to another. In milder cases, symptoms can resemble those of the flu: fever, headaches and general achiness.

9. Why are infected people who have been temporarily prevented from giving blood subsequently allowed to donate blood?
The West Nile Virus only stays in the blood of an infected person for four to seven days. After this period, the blood contains antibodies, but not the virus as such. Infection can only be transmitted if the blood contains the active virus. It is possible to give blood again after temporary exclusion. The required exclusion period constitutes an additional margin of safety intended to ensure that the virus is no longer present in the blood.

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