With national blood supplies short, the U.S. Food and Drug Administration recently changed restrictions on eligibility for donating blood in order to prevent the spread of bovine spongiform encephalopathy, more commonly known as mad cow disease.

The decision came after the American Red Cross announced a plan to defer donors who have received blood transfusions or traveled in the United Kingdom or Europe for certain periods of time, said Mark Shields, American Red Cross Hawkeye Chapter communications specialist.

“They’re concerned because of the emergence of a new human disease, vCJD (variant Creutzfeldt-Jakob Disease),” said Neil Cashman, professor of neurology at the University of Toronto.

He said although there has not been a single recorded case of the transmission of this human form of mad cow disease through blood or blood products, but there is still cause for concern.

Experiments with mice and sheep have shown that the infectious agents of mad cow disease can be passed through blood, he said.

Cashman said it is difficult to say whether the stricter rules on blood donations are necessary.

“I personally think that there is a risk of transferring vCJD through blood or blood products,” he said.

“The risk at present is a theoretical risk and that must be balanced against the real risk of deferring donors whose blood is vitally important to the blood supply.”

Shields said safety is always the Red Cross’s first priority.

“The American Red Cross believes firmly that you don’t have to sacrifice the highest possible safety standards for blood availability,” he said. “We’re enacting this policy because mad cow disease is an area of scientific ambiguity. We are enacting this policy out of an abundance of caution.”

He said 8 percent of donors could potentially be deferred by the new rules.

At a time when there are already summer blood shortages in several major cities, the Red Cross is trying to increase their donor pool to make up for this shortage and to prepare for a possible decrease in supplies in September, he said.

“We’re making a special call to all first-time donors and to lapsed donors,” he said.

Shields said only about 5 percent of the eligible adult population gives blood.

“There are a lot of people out there who could give blood but don’t,” he said. “We want to let these people know that this is a great way to help save someone else’s life.”

He said the Hawkeye Chapter of the Red Cross, which consists of parts of Iowa, Wisconsin, Illinois and Michigan, has always had a tremendous tradition of giving large supplies of blood.

Shields said the Red Cross needs to collect 900 units of blood daily in this region to meet their demands.

“The Red Cross is going to count on [the people of this region] more than ever to help patients,” he said.

He said the blood donated to a Red Cross chapter does not necessarily stay where it was donated, but is sometimes sent to other areas where it is needed.

Annually, the Red Cross collects six million units of blood from volunteers, providing almost half of the nation’s blood supply, he said.

A mad cow disease expert at the National Animal Disease Center was unable to comment because supervisors banned any communication with the media concerning this topic.