Canadian Blood Services said it was testing blood with a diagnostic test first implemented on June 23.

West Nile virus is carried and spread by mosquitoes and can cause fatal inflammation of the brain or membranes covering the brain or spinal cord.

In Ontario, in 2002, there was one confirmed death from West Nile virus and about a dozen other people who infected with the virus also died. In the United States, the virus caused 274 deaths last year.

"It normally takes two to three years to develop and implement a blood system test, but we have been able to do it in less than a year," Dr. Graham Sher, chief executive officer of Canadian Blood Services, said in a statement.

Federal and provincial health authorities in Canada are monitoring dead birds that may carry the virus and spraying areas where mosquitoes breed to prevent the spread of the disease.

Experts have long feared that West Nile virus might be spread through blood transfusions and companies have been racing against the clock to develop a test that will screen out blood from people infected by the virus.

Another viral disease, severe acute respiratory disease, killed 39 people in and around the Toronto area and infected nearly 400 people since it came to Canada in March.