Epidemiology of transmissible spongiform encephalopathies (prion diseases) in Austria

Between 1969 and 1996, transmissible spongiform encephalopathy was definitely diagnosed by autopsy and/or biopsy in 98 Austrian patients. The yearly incidence increased significantly in past years (1996: 1.41 cases per million inhabitants). This increase likely results from increased awareness in the medical community and effectuation of the diagnostic autopsy. The new variant of Creutzfeldt-Jakob disease (CJD), probably transmitted from bovine spongiform encephalopathy (BSE), has not occurred in Austria. The percentage of patients older than 70 years increased until 1989 and declined slightly thereafter. One patient received a dura mater graft 11 years before death. Another patient had familial CJD with a glutamatelysin mutation on codon 200 of the prion protein (PrP) gene PRNP. One more patient died from Gerstmann-Straussler-Scheinker disease (GSS), three patients from fatal familial insomnia (FFI). Another patient received intramuscular injections of a purified RNA preparation (Regeneresen) produced from various organs including brain. The age at death symmetrically distributes around a median of 64 years. Two CJD patients were unusually young (27 and 30 years). Most patients (72.7%) died within 6 months of disease. Retrospectively, 81% of patients had clinical diagnostic criteria of probable or possible CJD (52% probably and 29% possible). In 19%, clinical criteria for CJD were not fully met. There is no case clustering with specific professional groups or geographic areas. However, residents of Vienna, or Vienna and Lower Austria, respectively, had CJD diagnosed twice or three times more frequently than the rest of the country, indicating regionally differing qualities of case retrieval.