Miami Herald - Saturday, September 7, 2002
Fred Tasker, ftasker@herald.com

But they acknowledge up to 150,000 people may have been infected with the virus. Even if they develop no symptoms, they could pass on the infection through blood donations.

Doctors have no way to screen donated blood for the virus. And they're working with memories from the early 1980s when thousands of people died of AIDS after contracting HIV through blood transfusions because there was no way then to screen donated blood for that virus. Thousands contracted hepatitis in the 1960s and 1970s before there was effective screening.

The parallels are not exact. HIV and hepatitis remain in the bloodstream forever, while the West Nile virus lasts a few weeks -- greatly lessening the chances that blood donors would transmit the virus.

Experts at the Centers for Disease Control and Prevention believe in the blood supply.

"The medical benefit of getting blood or organs far outweighs any potential risk of getting West Nile virus transmission from blood or organs," said Dr. Lyle Petersen, the CDC's deputy director for the Division of Vector-Borne Infectious Diseases.

CONCERNS

Still, the earlier blood problems haunt medical experts.

"You can just close your eyes, step back in history and substitute the word HIV for West Nile virus," said Dr. Margaret Fischl, director of the AIDS medical research unit at the University of Miami School of Medicine.

"They say the likelihood is slim now. Hopefully that's correct. But there are questions that have to be answered before we can categorically say the blood supply is safe."

Many blood experts give the CDC high marks.

"It's always hard to walk the line between being candid with the public and yet not scaring them off," said Dr. John McCullough, director of the Biomedical Engineering Institute at the University of Minnesota.

In assessing the new cases, researchers from the Food and Drug Administration and the CDC are asking:

- Did the Georgia woman get the virus from a mosquito bite before the auto crash that killed her? She died Aug. 1. Or was it from the blood of one or more of the 63 donors that she was given as doctors tried to save her?

- Did she transmit the virus to the organ recipients through blood that her organs contained, or was the virus in the cells of the organ itself?

If she got the virus from a mosquito and passed it on through her donated organs alone, then new precautions might be needed for organ transplantation, but America's donated blood supply probably would be safe.

However, if she got it from the blood she was given and/or passed it on through her own blood, it could raise concerns about the safety of donated blood.

On Thursday, Dr. Anthony Marfin, epidemiologist with the CDC, estimated that 110,000 to 150,000 people nationwide may have been infected so far with the West Nile virus, with the peak season continuing through September. So far there have been 854 confirmed cases of West Nile-related meningitis or encephalitis and 43 deaths.

If some of those infected donate blood, a small part of the country's blood supply could be tainted. Potential donors are questioned about how they feel. Those reporting flu symptoms are turned away. But not all those infected suffer symptoms or the symptoms might not show up for a week or more, creating a window in which a person might unknowingly donate infected blood.

"So there's not an absolutely zero risk," said McCullough, the blood banking expert. "But there may be only a handful of infectious units [of donated blood] in the U.S. each year."

Of those who receive infected blood, only about one in 150 will develop a serious health problem, experts say.

"We're talking about very small numbers," said Dr. Eugene Schiff, director of the Center for Liver Diseases at the UM School of Medicine. "It's important not to create a situation in which somebody who desperately needs blood says he doesn't want it."

For decades, disease transfers at blood banks have been a problem, although the situation has improved since tests have been developed to screen donated blood for HIV, hepatitis and other diseases.

'CLOTTING FACTOR'

The biggest shadow over blood donations came from a medical advance in the 1970s -- "clotting factor." Made of proteins from blood plasma, it could arrest the bleeding of people with hemophilia.

But a single dose came from proteins culled from up to 20,000 donors -- hugely multiplying the danger of HIV infection. The result: 4,000 deaths and more than $600 million in lawsuits against health companies.

Today, people with hemophilia are treated with a manufactured product that contains little blood material and is sterilized, eliminating HIV infections.

The difficulty of combatting such infections also is illustrated by the decades-long fight against hepatitis.

In the 1960s, as many as 15 percent of U.S. patients who received transfusions during heart surgery contracted hepatitis, Schiff said.

The infection rate dropped to nearly zero after 1990, when tests were created to screen for all types of hepatitis.

Schiff believes the CDC and FDA are doing all they can. Still, there are factors that might make the West Nile virus somewhat less transmittable than HIV or hepatitis:

- HIV and hepatitis can stay in a person's bloodstream for life. West Nile virus appears to last only a few weeks.

Dr. Jesse Goodman, deputy director of the FDA Center for Biologics Evaluation and Research, said "it's not like there are large populations running around with West Nile virus constantly circulating in their blood."

- That all four recipients of the Georgia woman's organs contracted West Nile virus might have a simple explanation. Organ recipients typically are given medications to suppress their immune systems so they won't reject the organs. Other patients receiving transfusions infected by the virus -- otherwise healthy crash victims, for example -- might better fight it off.

A CDC analysis published in Transfusion Magazine determined the theoretical risk of a donor transmitting West Nile virus in his or her blood is about one in 5,000.

So far, the CDC has advised transplant doctors to be alert for West Nile in their patients. Blood banks are being urged to pay attention to would-be donors, screening out any who have flu-like symptoms that accompany one stage of the West Nile virus.

Meanwhile, medical experts continue watchful waiting.

"There is a risk," Kleinman said. "But if you need blood for medical reasons, the risk is so small that it is outweighed by the benefits.

"And you're a heck of a lot more likely to get West Nile from a mosquito than from a transfusion."

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