Blood banks and centers around the nation may be noticing a slight decrease in the number of blood donations this winter.

The Food and Drug Administrative recently announced a possible transmission of the new variant Creutzfeldt-Jakob disease (nvCJD), otherwise known as the “mad cow” disease.

As a result of this new strain, donor candidates who have resided in the United Kingdom for a consecutive period of at least six months during 1980 and 1996 will not be allowed to give blood.

Jackie Cacciatore, director of public relations at The Blood Center of Central Iowa, said nvCJD is a slow-developing disease that affects the central nervous system.

“At this point, the FDA is not sure if the disease can be transmitted by blood,” Cacciatore said. “There are no cases known through blood transfusions currently. It’s basically a theory, but at this point the FDA is not taking any risks, so precautions must be taken.”

Cacciatore said there are no known cases of the new variant CJD in the United States.

“There is a theory that the 39 reported cases from people in the United Kingdom obtained the CJD by eating infected cattle,” she said. “But there is no evidence of transmission from the new variant CJD.”

Cacciatore said the policy change could negatively affect the blood supply in central Iowa.

“The deferral is indefinite and could actually affect donations nationwide, putting us at a loss of 2.2 percent, or about 100 donors in central Iowa a month,” Cacciatore said.

John Elliot, supervisor of the blood bank at the Mary Greeley Medical Center, 1111 Duff Ave., said he was notified by the FDA several weeks ago about the deferent but has not seen any dramatic decrease in blood donations.

“The donations have been low, but that is only due to the holidays, not because of the recent notice,” Elliot said. “Overall, it is not affecting that large of a number of people.”

Elliot said there is no urgent need to compensate for the lack of donations right now, although he said the deferent will be permanent pending notification from the FDA.

“We will not be allowing any donors from who lived in England during the given time until more testing has been done by the FDA and the deferral is dispelled,” he said.