Increased incidence of sporadic Creutzfeldt-Jakob disease in the age groups between 70 and 90 years in Belgium

From 1998 a prospective surveillance study of Creutzfeldt-Jakob disease (CJD) has been initiated in Belgium. In addition to epidemiological data, information on cerebrospinal fluid biomarkers, prion protein gene and brain neuropathology was collected. From 1-1-1998 to 31-12-2004, 188 patients were referred to the surveillance system. In 85 patients a ‘definite’ diagnosis of sporadic CJD (sCJD) could be made, whereas 26 patients remained ‘probable’. We further identified two unrelated patients with an E200K mutation, and two patients with a seven octapeptide repeat insertion in one family. In one patient a familial history was noted but genetic analysis was not performed. In 72 patients different final diagnoses were made, Alzheimer’s disease being the most frequent (N = 20). The demographic parameters of the Belgian population were similar to those observed in the rest of Europe. We did notice a significantly increased age-specific incidence (‰>‰6/106/year) of sCJD patients between 70 and 90 years old in the period 2002–2004 compared to 1998–2001 and retrospectively obtained data (1990–1997, p < 0.01). We undertook a detailed clinical and biochemical analysis to investigate this increase but could not identify any reason other than an increased vigilance for the diagnosis.