Creutzfeldt-Jakob disease in Australia 1970-1999

To ascertain all persons who developed a transmissible spongiform encephalopathy (TSE) within Australia during the 30-year period 1970 to 1999 through a comprehensive national surveillance program and subject the group to detailed epidemiologic analysis.

Cases were ascertained through reviews of morbidity separation coding data from all university-affiliated tertiary referral hospitals, as well as the centralized data bases of state and territory health departments, regular national death certificate searches, and semiannual mailout questionnaires to all neurologists and pathologists throughout Australia. Prospective monitoring commenced in September 1993.

A total of 387 patients were confirmed as having TSE during this epoch. The majority of cases were sporadic Creutzfeldt-Jakob disease (CJD) (90.7%), with 7.2% heredofamilial and 2.1% iatrogenic. Over this 30-year period, the national average annual sporadic CJD incidence rate per million progressively increased from 0.31 for the decade 1970 through 1979 to 0.77 for 1980 through 1989, reaching 1.03 for 1990 through 1999. Death certificates were found to have a false-positive rate of 11.5% and sensitivity of 83.0% for sporadic CJD.

Within Australia, there has been a gradual increase in the incidence of transmissible spongiform encephalopathy over the three-decade period 1970 through 1999, peaking in 1999 at 1.4/million/year for sporadic Creutzfeldt-Jakob disease. This increase is believed secondary to improved case ascertainment. Variant Creutzfeldt-Jakob disease was not identified during this period. Age- and sex-adjusted comparisons showed a decline in incidence rates in the elderly in both sexes, usually from age 74 years. Death certificates were a useful but imperfect method of case detection.