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Surveillance for Creutzfeldt-Jakob Disease -- United States
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 greater than 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 less than 30 years (2). In comparison, in the United States, deaths associated with CJD among persons aged less than 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 less than 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 less than 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 less than 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 Program ** 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: 16.3 million). 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 greater than 90% of pathologists in three areas were contacted. In addition, clinical and neuropathologic records for each CJD patient aged less than 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%) of the 94 patients were aged less than 55 years; one of the nine was aged less than 45 years, and none were aged less than 30 years.
The clinical and neuropathologic record review of the nine patients aged less than 55 years did not identify any with the variant form of CJD. A brain biopsy was performed for the one decedent who was aged less than 45 years, and an autopsy was performed for four of the other eight. One decedent for whom there was no brain biopsy or autopsy was a familial case of CJD from a family that had a known genetic abnormality associated with CJD.
One additional CJD patient aged less than 45 years who died in early 1996 was identified by the surveillance teams. This decedent's clinical history was similar to the description of the new variant of CJD, but brain pathology at autopsy was inconsistent with that diagnosis.
Of the 94 CJD deaths, 81 (86%) were identified from death certificate review. For the 13 deaths that were identified only through survey of neurologists, neuropathologists, or pathologists, the death certificate either was not coded as CJD or had not yet been filed.
Reported by: A Reingold, MD, Univ of California at Berkeley, G Rothrock, MPH, California Emerging Infections Program, M Starr, DVM, K Reilly, DVM, D Vugia, MD, S Waterman, MD, State Epidemiologist, California State Dept of Health Svcs. R Marcus, School of Medicine, Yale Univ, New Haven; M Cartter, MD, J Hadler, MD, State Epidemiologist, Connecticut State Dept of Public Health. M Farley, MD, M Bardsley, MPH, W Baughman, MSPH, Atlanta Metropolitan Active Surveillance Project, J Koehler, DVM, K Toomey, MD, State Epidemiologist, Div of Public Health, Georgia Dept of Human Resources. R Danila, PhD, K MacDonald, MD, M Osterholm, PhD, State Epidemiologist, Minnesota Dept of Health. E DeBess, DVM, S Ladd-Wilson, MS, P Cieslak, MD, D Fleming, MD, State Epidemiologist, Oregon Health Div. State Br, Div of Applied Public Health Training (proposed), Epidemiology Program Office; Office of the Director, National Center for Infectious Diseases; Special Pathogens Br and Office of the Director, Div of Viral and Rickettsial Diseases, National Center for Infectious Diseases, CDC.
Editorial Note: This analysis did not detect evidence of a recent outbreak of the newly described variant of CJD in the United States. Limitations of the surveillance data include the absence of neuropathologic examinations of brain tissue for many patients with CJD and the limited size of the population under active surveillance. Nonetheless, the conclusions also are supported by a review of 67 brain specimens from confirmed CJD patients in the United States submitted during 1991-1996 to the University of California at San Francisco, a CJD neuropathology center; none of these specimens had the neuropathologic features of the variant form of CJD (S. DeArmond, and S. Prusiner, University of California at San Francisco, personal communication, 1996).
The active surveillance efforts also confirmed the findings of an earlier study indicating that death certificate reviews identify greater than or equal to 80% of CJD deaths in the United States (4). To broaden surveillance for the variant form of CJD in the United States, CDC is encouraging physicians to increase their index of suspicion for this illness and, with state and territorial epidemiologists, is investigating CJD deaths among persons aged less than 55 years identified through routinely reported mortality data. CDC also is working with the American Association of Neuropathologists to improve surveillance for CJD in all age groups. Recent experimental evidence involving intracerebral inoculation of cynomolgus macaque monkeys with brain tissue obtained from cattle with BSE supports a possible causal link between BSE and the variant CJD (5). Therefore, ongoing CJD and BSE surveillance in many countries of the world, including the United States and especially in the UK, will be critical for determining whether and to what extent the agent of BSE is causing disease in humans. This need is underscored by the report during March 20-June 26, 1996, of two additional confirmed cases of the newly recognized variant of CJD in persons with onset at age less than 30 years, one in France and one in the UK (6).
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 accumulation at high concentration, indicated by immunocytochemical 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). ** 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.
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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, + 1991-1995 ============================================================ Age group (yrs) ---------------------------- Year <55 Yrs >=55 Yrs Total ------------------------------------- 1991 2 17 19 1992 2 & 17 19 1993 1 17 18 1994 1 18 19 1995 3 16 19 Total 9 85 94 Rate & 0.1 5.3 1.2 ------------------------------------------------------------ * Per million population. + Emerging Infections Program 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: 16.3 million). & One case occurred in a person aged <45 years. ============================================================
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