(HealthDay is the new name for HealthScoutNews.)
WEDNESDAY, June 18, 2003 (HealthDayNews) -- On Thursday, the Indiana Blood Center in Indianapolis starts screening donations for West Nile virus. America's Blood Centers are not far behind, with screening scheduled to start on Friday. And the Blood Bank of New Jersey will be up and running July 1, the unofficial beginning of West Nile season.
Thanks to new tests being released under U.S. Food and Drug Administration's (FDA) Investigational New Drug (IND) protocols, every single blood collection center in the United States will eventually be following suit.
"We're all getting ready to come up," says Dr. Louis Katz, president of America's Blood Centers in Davenport, Iowa. "We'll be up and running before the risk to the blood supply is substantial." The risk rises after July 1, when most cases of West Nile occur.
Mosquitoes most often transmit West Nile, which was first identified in the United States in 1999. Last year, however, health officials confirmed that at least 21 people had been infected via organ or blood transfusions.
This is a troubling trend because West Nile is extremely stealthy, producing no symptoms in the vast majority of its victims. About 20 percent of people infected develop flu-like symptoms, while one in 150 develop life-threatening illness such as encephalitis. West Nile is also not a so-called lifestyle disease, making it difficult if not impossible to screen with questionnaires and such.
Last November, the FDA asked companies to create a test to screen blood donations for the virus. "West Nile virus was deemed such a threat to the blood supply because all studies were showing that this year's West Nile virus season is going to be worse than last year -- and it's spreading to the West Coast," says Kim Weissenburger, a spokeswoman for Chiron, the Emeryville, Calif., company that developed the Procleix West Nile Virus Assay.
The FDA's IND protocol lets tests be released with limited testing while requiring that additional data be collected during the first year of its use.
The Procleix assay, as well as a similar product from Roche, are nucleic acid tests. These particular tests detect the actual virus, not antibodies, and can therefore pick up on an infection earlier.
HIV and hepatitis C nucleic acid tests were released under the same investigational protocol. However, Katz says, scientists knew more at the time about the viral reproduction dynamics in HIV and HCV than they do in West Nile.
"There's a possibility that it's not going to work as well," Katz says. "This is really an investigational study in every sense of the word, so at the end of the West Nile season, we're going to have a much better idea of whether it works as well as we want it to."
Katz is confident the risk to the public is not great. "The worst estimate is that it's going to be 80 percent effective at identifying potentially infectious donors," he says.
One way or another, things are changing at the nation's blood collection centers. "When people donate, they must read the information sheet that their blood is going to be tested for West Nile as part of this research study or they will not be able to donate," says Judy Daniels, a spokeswoman for the Blood Center of New Jersey in East Orange. "We are also asking an additional question on our donor registration form: Have you had a headache with fever in the last week? Those are very common symptoms that come with West Nile and we will defer people who say yes to that question."
A recent survey completed by 3,998 blood donors at sites run by the American Red Cross and America's Blood Centers revealed that about 1 percent of donors would be excluded from donating because they had recently experienced various symptoms that could indicate a West Nile infection.
"I think turning away donations as a result of testing is not going to be a big issue," Katz says. "The models that the CDC [Centers for Disease Control and Prevention] has provided to us suggest that the worst case scenario in the worst epidemic spots at the peak of the epidemic would have been 20 per 10,000. That's [0].2 percent. We can live with that."
Daniels estimates that deferrals will be 1 percent to 2 percent. "It's one more reason why we might have to turn away donors, but obviously we're protecting the blood supply as well as we can," she says.
More information
For more on West Nile virus, visit the U.S. Centers for Disease Control and Prevention. For more on the safety of the blood supply, try the American Association of Blood Banks.
