Prion disease in Indigenous Australians.

BACKGROUND: Indigenous Australians are of increased risk of developing dementia - Alzheimer's disease and mixed dementia diagnoses are the most common. Whilst prion diseases have been reported in Indigenous peoples of Papua New Guinea and the United States of America, the occurrence and phenotype of prion disease in Indigenous Australians is hitherto unreported. AIM: Report the incidence rate and clinical phenotype of Creutzfeldt-Jakob disease (CJD) in Indigenous Australians. METHOD: Calculation of crude sporadic CJD (sCJD) incidence rates and indirect age-standardisation of all CJD to calculate the standardised mortality ratio (SMR) for the Indigenous Australian population in comparison to the all-resident Australian population, along with analysis of clinical phenotype. RESULTS: Illustrative case report of an Indigenous Australian from regionally remote Western Australia dying from typical "probable "sCJD two months after disease onset, with Australian National CJD Registry (ANCJDR) surveillance overall ascertaining eight Indigenous Australians dying from sCJD (5 post-mortem confirmed, 3 classified as "probable") with the clinical phenotype similar to non-Indigenous people, including median age at death of 61 years (interquartile range IQR = 16 years) and median duration of illness 3 months (IQR = 1.6 months). Indigenous Australians with sCJD were geographically dispersed throughout Australia. The calculated overall crude annual rate of sCJD in Indigenous Australians compared to the remainder of the Australian population was not significantly different (0-3.87/million for Indigenous Australians; 0.94-1.83/million for non-Indigenous). The indirect age-standardised all CJD mortality ratio for the Indigenous population for the years 2006 to 2018 was 1.49 (95% CI, 0.75-2.98), also not significantly different to the all-resident Australian population. CONCLUSION: CJD occurs in Indigenous Australians with the clinical phenotype and occurrence rates similar to non-Indigenous Australians. These findings contrast with a previous report wherein the incidence rate of CJD in a non-Australian Indigenous populations was reported as decreased. This article is protected by copyright. All rights reserved.