Creutzfeldt Jacob Disease CJD and variant Creutzfeldt Jacob Disease vCJD

CJD is a rare degenerative, fatal disorder of the central nervous system. Worldwide, its incidence is about one person per million per year. CJD can affect humans in three ways: sporadic CJD, which has no known risk factors and accounts for 85 percent of CJD cases; hereditary CJD, which occurs in individuals with a family history of the disease and tests positive for specific genetic mutations; and acquired CJD, which is transmitted by exposure to brain or nervous system tissue. Acquired CJD accounts for less than 1 percent of CJD cases, and has occurred most in individuals that received repeated injections of human pituitary gland growth hormone. This preparation was prepared from pools of pituitary glands from a number of cadavers. Through the 1950s it was used to treat congenital dwarfism, although this practice was subsequently supplanted by a synthetic growth hormone preparation. CJD also has been transmitted to patients who have undergone brain surgery, including transplant of the dura mater - the covering of the brain and spinal cord. This material was harvested from human cadavers and then used in some brain operations. The dura mater had been stored in a vat along with dura mater from other cadavers that had contaminated material. Affected individuals may take decades to develop symptoms, and then progress rapidly to dementia, severe loss of coordination, and death. While the cause of CJD remains uncertain, the suspicion now is that it occurs in response to abnormal changes in the shape of brain prions. Currently, there is no screening test for the disease, and while blood transfusions have never been shown to transmit CJD, as a precaution the Food and Drug Administration (FDA) prohibits blood donation by individuals who may be at risk. These include potential donors who have received injections of human-derived pituitary hormone, those with a family history of CJD, or those who have had surgeries that involved transplanted dura mater.

Similar to CJD, and an issue with regard to travel, is variant Creutzfeldt-Jacob Disease (vCJD). It also is a rare, degenerative and very similar fatal disorder of the central nervous system, thought to occur after humans have eaten beef contaminated with bovine spongiform encephalopathy (BSE, or "mad cow" disease). In 1996 the first cases of vCJD were reported in the United Kingdom, and there soon was concern on the part of blood banks and public health officials that it could contaminate the blood supply. To date the problem has remained quite rare, with only cases in the United Kingdom (UK) and a few in France and Italy. There has been one case in the United States, but it was in a person who had lived in the UK during the period of greatest risk. So far there have recently been two cases, both in the UK and presumed to have been transmitted via blood transfusion. The USFDA policy seeks to strike a reasonable balance between guarding against the risk of spreading vCJD through blood-banking, and preserving the supply of blood products for medical use. Currently, the policy relates to travel and residence in Europe, and recommends the following individuals be deferred indefinitely:

• those that spent a total of three months or more in the United Kingdom (UK) from the beginning of 1980 through the end of 1996; or who have spent a total of five years or more in Europe from 1980 to the present

• current or former US military personnel, civilian military employees, and their dependents that resided at US military bases in Northern Europe (Germany, UK, Belgium, and the Netherlands) for a total of six months or more from 1980 through 1990; or that resided elsewhere in Europe, such as Greece, Turkey, Spain, Portugal, or Italy, from 1980 through 1996

• those that received any blood or blood component transfusions in the UK between 1980 and the present

• persons that injected bovine insulin since 1980 from cattle raised in the United Kingdom, unless it is possible to confirm the product was not manufactured after 1980 from cattle in the UK.

Guidelines also were issued in 2001 by the US Department of Defense (DoD). They also relate to travel and residence in Europe, and recommend active-duty military personnel, civil service employees, and their family members defer indefinitely from giving blood if:

• they traveled or resided in the UK for a cumulative total of three months or more at any time from 1980 through the end of 1996

• they received a blood transfusion in the UK at any time from 1980 to the present

• they traveled to or resided anywhere in Europe for a cumulative total of six months or more at any time from 1980 through the end of 1996; or traveled to or resided anywhere in Europe for a cumulative total of five years or more at any time from 1 January 1997 to the present.

These policies are under constant review by the FDA in light of new information about vCJD and BSE.

There has been much discussion about the development of a test for vCJD that could be used to screen blood donors, but there has been little real progress. In order to be sensitive enough to identify virtually all potentially infectious donations, almost all screening tests will have a false-positive rate. To deal with this it is necessary to have a suitable confirmatory test prior to beginning donor screening. The rationale is that, with the risk of transmission by transfusion being so small, it would be unacceptable to be in a situation of notifying a fair number of volunteer blood donors that they have a test result suggesting they may later develop a fatal disease for which there is no treatment, and when there is uncertainty about the meaning of the test result.

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