THURSDAY, Sept. 19, 2002 (HealthDayNews) -- Health officials may soon call for screening of blood and blood products for the West Nile virus, which almost certainly can be transmitted through transfusions and organ transplants.
"At this time, the results are not totally conclusive," says Dr. Jesse Goodman, a U.S. Food and Drug Administration infection expert. But "it is most prudent to assume" that transmission can occur through blood and tissue donation.
Officials say they're investigating seven cases of blood and organ recipients who contracted West Nile meningitis, encephalitis -- infections of the brain lining or the organ itself -- or fever linked to the virus. "FDA really believes that since this transmission by transfusion is likely, we will need to move rapidly toward testing of donor blood," Goodman says.
However, health officials are bedeviled by the lack of a keen test for West Nile in the blood supply. The protein markers of infection, called antibodies, take some time to appear after the virus enters the bloodstream, so a person can be infectious before the pathogen can be detected or symptoms arise. Compounding the problem, levels of West Nile virus in blood are typically lower shortly after infection than those of other viruses tested, such as hepatitis C or HIV.
Screening for viral genetic material is a finer net, but it's also more difficult and time-consuming, Goodman says. "This is a route that has been taken to tremendously improve the safety of our blood supply for other pathogens," he adds.
Goodman says people who have elective surgeries planned may want to consider delaying the operations until a test for West Nile is available. They may also want to consider stockpiling their own blood for the procedure. Currently, he adds, officials have "too little information to make a general recommendation."
Health officials are also warning doctors to consider West Nile infection in people with sudden bouts of polio-like paralysis.
Acute flaccid paralysis is an uncommon effect of West Nile encephalitis, but the Centers for Disease Control and Prevention (CDC) says several patients this year have developed the condition.
Experts have believed the muscle weakness associated with West Nile was part of a nerve problem called Guillain-Barré syndrome (GBS). However, Dr. Jim Sejvar, a medical epidemiologist at the CDC's National Center for Infectious Diseases, says the paralysis may in fact be closer to polio.
The distinction's important, Sejvar says, because the two treatments for GBS can have potent side effects but aren't effective against polio-like illnesses. "If the person does not need that treatment, it could potentially do more harm than good," he explains.
Officials say that as of Wednesday, 1,641 people have contracted West Nile this year, and 80 have died from the virus. Human cases have occurred in 36 states and Washington, D.C., with North Carolina the latest to join the list.
Nearly all of the cases are the result of mosquito bites, says Dr. Lyle Petersen, a CDC West Nile expert. Petersen says the outbreak appears to be tapering off in the South, but it's too soon to tell if it's fading in the North and Midwest.
Dr. Louis M. Katz, who heads the transfusion transmitted disease committee of the American Association of Blood Banks, says he believes West Nile can be passed from person to person by blood donations. However, he's not convinced the nation's blood supply needs screening for the virus.
"Lots of things are transmitted by blood that we don't test for that may be more frequent than West Nile," says Katz, vice president for medical affairs at the Mississippi Valley Regional Blood Center. These include Chagas disease, which is caused by a parasite that eludes current screening methods, and bacteria that infect platelets.
In addition, Katz says the epidemiology of the West Nile outbreaks may affect the testing debate. In Israel, the disease surged in the 1950s but quickly died down and now appears only in sporadic blips. If the same pattern holds in the United States, policymakers who opt for testing will have to consider when to stop, since screening is expensive and strains blood labs.
Tests for HIV and hepatitis C, for example, can run $10 each, and there are 14 million blood donations each year in this country. Laboratories are already complaining that they're taxed doing DNA screening for these two viruses, Katz says.
Screening experts and government health officials will meet tomorrow to discuss the evidence of West Nile's transmissibility in blood and organ donations. So to test or not to test will soon be determined, Katz says. If the answer is yes, no screening tool for the virus will be available before the end of the current mosquito season, which lasts only a few more weeks, he says.
What To Do
For more on West Nile virus, visit the Centers for Disease Control and Prevention. For more on the safety of the blood supply, try the American Association of Blood Banks.
