Surveillance for Creudtzfeldt-Jakob disease - United States

Morbidity and Mortality Weekly Report, August 9, 1996

Creutzfeldt-Jakob disease (CJD) in humans and bovine spongiform encephalopathy (BSE) in cattle are subacute degenerative diseases of the brain classified as transmissible spongiform encephalopathies. BSE was first identified in 1986 in the United Kingdom (UK), where an epizootic involving >155,000 cattle appeared to have been greatly amplified by exposure of calves to contaminated rendered cattle carcasses in the form of meat and bone meal nutritional supplements (1). On March 20, 1996, an expert advisory committee to the government of the UK (1995 estimated population: 58.3 million) announced its conclusion that the agent responsible for BSE might have spread to humans, based on recognition of 10 persons with onset of a reportedly new variant form of CJD(*) during February 1994-October 1995. The 10 persons ranged in age from 16 to 39 years (median age at illness onset: 28 years); of the eight persons who had died, five were aged <30 years (2). In comparison, in the United States, deaths associated with CJD among persons aged <30 years have been extremely rare (median age at death: 68 years) (3). As a result of the newly recognized variant of CJD described in the UK, CDC updated its previous review of national CJD mortality (3 ) and began conducting active CJD surveillance in five sites in the United States. These reviews did not detect evidence of the occurrence of the newly described variant form of CJD in the United States.

National CJD Mortality Data

Based on multiple cause-of-death data obtained from CDC's National Center for Health Statistics, the annual death rates for CJD (International Classification of Diseases, Ninth Revision, code 046.1) during 1979-1994 were stable at approximately 1 case per million population (Figure 1). Data for 1979-1993 are final; 1994 data are provisional.

The number of deaths attributed to CJD among persons aged <45 years ranged from zero in 1984 to eight in 1981 and 1993. In most years no CJD-associated deaths were reported among persons aged <30 years; no year had more than one. During 1990-1994, CJD was coded as a cause of death on the death certificate for two persons aged <30 years. One of these two died in 1993 and had been previously identified as part of ongoing surveillance for CJD among recipients of pituitary-derived human-growth hormone; the other died in 1994, but was excluded from analysis because follow-up investigation revealed a postmortem examination that did not confirm the initial CJD diagnosis but indicated a diffuse T-cell proliferative disease.

Active CJD Surveillance

In early April 1996, active surveillance for the newly reported variant of CJD and physician-diagnosed CJD cases was conducted in four Emerging Infections Programt sites (Connecticut, Minnesota, Oregon, and the San Francisco Bay area of California) and the Division of Public Health, Georgia Department of Human Resources, along with the Atlanta Metropolitan Active Surveillance Project (total 1993 population for these areas: 16.3million). CJD deaths were defined as any deaths that the surveillance teams in each of these five sites identified as having been attributed to CJD by a physician. Surveillance efforts included review of available death certificate data during 1991-1995 and contact by phone, mail, or fax with neurologists, neuropathologists, and pathologists to identify patients who died from CJD during 1991-1995. Approximately 800 neurologists and neuropathologists, constituting 92%-100% of these specialists in these surveillance areas, and >90% of pathologists in three areas were contacted. In addition, clinical and neuropathologic records for each CJD patient aged <55 years were sought for review.

A total of 94 deaths attributed to CJD were identified in the active surveillance areas during 1991-1995. The annual number of CJD deaths was stable (mean: 19; range: 18-19), and the average annual CJD death rate was 1.2 (range by site: 0.7-1.7) per million population (Table 1). Consistent with the national CJD mortality pattern, nine (10%) ofthe 94 patients were aged <55 years; one of the nine was aged <45 years, and none were aged <30 years.

TABLE 1. Number of deaths from Creutzfeldt-Jakob disease, by year
and age group,
and average annual death rate,(*) by age group-active surveillance
sites,([dagger] 1991-1995

[Figure 1 ILLUSTRATION OMITTED]

(*) This newly recognized variant of CJD has been characterized by a specific, uniform brain pathologic profile and the classical, pathognomonic spongiform changes of CJD found on histologic examination of brain tissue. This profile includes, in both the cerebellum and cerebrum, numerous kuru-type amyloid plaques surrounded by vacuoles and prion protein accumuiation at high concentration, indicated by immunocytochemicai analysis. Atypical clinical features include prominent behavior changes at the time of clinical presentation with subsequent onset of neurologic abnormalities, including ataxia within weeks or months, dementia and myoclonus late in the illness, a duration of illness of at least 6 months, and nondiagnostic electroencephalographic changes (2). ([dagger]) Emerging infections programs were established in 1994 through cooperative agreements between CDC and state health departments to conduct special surveillance and laboratory/epidemiologic projects and to pilot and evaluate prevention programs.

References

(1.) CDC. World Health Organization consultation on public health issues related to bovine spongiform encephalopathy and the emergence of a new variant of Creutzfeldt-Jakob disease. MMWR 1996;45:295-6,303.

(2.) Will RG, Ironside JW, Zeidler M, et al. A new variant of Creutzfeldt-Jakob disease in the UK. Lancet 1996;347:921-5.

(3.) Holman RC, Khan AS, Kent J, Strine TW, Schonberger LB. Epidemiology of Creutzfeldt-Jakob disease in the United States, 1979-1990: analysis of national mortality data. Neuroepidemiology 1995;14:174-81.

(4.) Davanipour Z, Smoak C, Bohr T, Sobel E, Liwnicz B, Chang S. Death certificates: an efficient source for ascertainment of Creutzfeldt-Jakob disease cases. Neuroepidemiology 1995;14:1-6.

(5.) Lasmezas Cl, Deslys JP, Demaimay R, et al. BSE transmission to macaques. Nature 1996;381: 743-4.

(6.) Chazot G, Broussolle E, Lapras C, Blattler T, Aguzzi A, Kopp N. New variant of Creutzfeldt-Jakob disease in a 26-year-old French man [Letter]. Lancet 1996;347:1181.