Relationship with BSE (Mad Cow Disease)
There is strong epidemiologic and laboratory evidence for a causal association between vCJD and BSE. The absence of confirmed cases of vCJD in other geographic areas free of BSE supports a causal association.
In addition, the interval between the most likely period for the initial extended exposure of the population to potentially BSE-contaminated food (1984-1986) and onset of initial vCJD cases (1994-1996) is consistent with known incubation periods for CJD.
An experimental study reported in June 1996 showed that three cynomologus macaque monkeys inoculated with brain tissue obtained from cattle with BSE had clinical and neuropathological features strikingly similar to those of vCJD (Nature 1996;381:743-4).
A study published in 1996 indicated that a Western blot analysis of infecting prions obtained from 10 vCJD patients and BSE-infected animals had similar molecular characteristics that were distinct from prions obtained from patients with other types of CJD (Nature 1996;383:685-90).
An experimental study involving inoculation of a panel of inbred mice with the agents causing BSE and vCJD substantially increased the strength of the scientific evidence for a causal association between vCJD and BSE (Nature 1997;389:498-501). In this study, groups of inbred mice and a group of cross-bred mice inoculated with brain homogenates from vCJD cases were reported to have had latency periods and lesion profiles consistent with the BSE pattern.
The latency period, neuropathology, and disease-causing PrP isoforms in transgenic mice expressing bovine PrP that were inoculated with vCJD, BSE, and scrapie brain extracts provided additional evidence supporting the link between BSE and vCJD (Proc Natl Acad Sci 1999;96:15137-42).
Increased Surveillance Efforts
The possibility that BSE can spread to humans has focused increased attention on the desirability of enhancing national surveillance for Creutzfeldt-Jakob disease (CJD) in the United States.
The Centers for Disease Control and Prevention (CDC) monitors the trends and current incidence of CJD in the United States using several surveillance mechanisms. On a routine basis, CDC reviews the national multiple cause-of-death data taken from death certificates and compiled by the National Center for Health Statistics, CDC. In addition, with the support of the Council of State and Territorial Epidemiologists, CDC conducts follow-up review of clinical and neuropathology records of CJD decedents aged <55 years who are identified through the national mortality data analysis or reported by health care workers. This is the age group in which almost all of the vCJD cases worldwide have occurred to date.
In 1996-97, CDC established, in collaboration with the American Association of Neuropathologists, the National Prion Disease Pathology Surveillance CenterExternal at Case Western Reserve University, which performs special state-of-the-art diagnostic tests for prion diseases, including post-mortem tests for vCJD.
Currently, CDC works with selected state health departments on various enhanced CJD surveillance projects and education programs regarding the importance of autopsy to both the surveillance and diagnosis of CJD. In addition, CDC collects, reviews and when indicated, actively investigates specific reports by health care personnel or institutions in all states of possible iatrogenic CJD and variant CJD cases.
These surveillance methods for CJD enhance the ability to identify cases of variant CJD when such cases occur in the United States.
For more information about surveillance and diagnosis of CJD, see the following article: Creutzfeldt-Jakob Disease surveillance and diagnosis. Belay ED, Holman RC, Schonberger LB. CID September 15 2005;41:834-836.
A summary of the analysis of multiple cause-of-death data was published in the Journal of the American Medical Association on November 8, 2000 (Volume 284, No. 18, pp. 2322-3) and in Clinics of Laboratory Medicine in December 2002 (Volume 22, pp. 849-62).