Prevention of vCJD rests first and foremost on preventing the occurrence of BSE in cattle by controls on animal feed ingredients, human food safety systems and bovine product imports, and on monitoring the occurrence of BSE in cattle through a BSE surveillance system. There has never been a case of vCJD without the potential link to exposure to BSE. If BSE is present in a herd, prevention of vCJD depends upon removing potential sources of exposure from the food supply, such as the brain and spinal cord of affected cattle. The U.S. government prohibits these and other SRM that are most likely to carry the BSE prion from entering the food supply. Because BSE-infected cattle may appear healthy, at-risk materials from all cattle are prohibited from entering the food supply. BSE surveillance in cattle is another important vCJD preventative element. Through December 2007, extensive BSE surveillance in the United States has documented three cases of BSE, including two unusual BSE cases in very old animals born in the United States and one classic or typical BSE case in a dairy cow born in Canada (see Incidence/Cases section). Largely because of this relatively low number of BSE cases, current BSE surveillance in the United States is less extensive than in some European countries and Japan but still exceeds international guidelines.
Just as with the prevention and control of BSE, the prevention and control of vCJD is supported by an effective national surveillance system for prion disease. Such surveillance for human prion disease plays a critical role in early detection of vCJD. In addition, public health officials, blood establishments and clinicians must guard against the spread of vCJD through blood transfusion, tissue transplantation and contaminated surgical instruments.
To prevent BSE from entering the United States, severe restrictions were placed on the importation of live ruminants, such as cattle, sheep, and goats, and certain ruminant products from countries where BSE was known to exist. These restrictions were later extended to include importation of ruminants and certain ruminant products from all European countries.4
Because the use of certain ruminant tissue in ruminant feed probably was a factor responsible for the BSE outbreak in the U.K. and because of the possibility of transmitting the BSE agents to humans, the U.S. Food and Drug Administration (FDA) instituted a ruminant feed ban in June 1997 that became fully effective as of October 1997.4 In late 2001, the Harvard Center for Risk Assessment study of various scenarios involving BSE in the United States concluded the FDA ruminant feed rule provides a major defense against this disease.4
In 2002, FDA, in accordance with recommendations from its Transmissible Spongiform Encephalopathy Advisory Committee, published guidance outlining a blood donor deferral policy designed to reduce both the theoretical risk of transfusion transmission of classic forms of CJD and the risk of transfusion transmission of vCJD.15
FDA’s guidance document protects the blood supply by excluding donors who meet any of the following criteria: residence in the U.K. for three months or more between 1980 and 1996; military personnel (current and former) and their dependents who spent six or more months on military bases in northern Europe 1980-1990 or southern Europe 1980-1996; donors who lived in France for five or more years since 1980; donors who received a transfusion in the U.K. 1980-present; blood donors who lived in Europe for five or more years 1980-present.15
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