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A clear increase in the annual incidence of Australian
TSEs was observed during the period of
1970 to 2000 (Figure 2). This increase has also
been observed in international CJD surveillance
units and probably refl ects case ascertainment
bias associated with heightened recognition and
case notifi cation as well as improved investigation
and case confi rmation. 4 Since 2000, the number of
TSE deaths has declined and stabilised at approximately
20 cases per year. In particular, a decline in
the number of probable cases has been observed
and this probably relates to a number of issues,
including broadened surveillance responsibilities
and diffi culties encountered following changes to
privacy legislation. For the period of 1970 to 2005,
the average annual age-adjusted mortality rate
was 0.85 deaths per million per year. During the
prospective period of ANCJDR surveillance from
1993 to 2005, the average annual rate of mortality
Figure 2. Number and age-standardised
mortality rate of ANCJDR definite and probable
cases, 1970 to 2005
Year of death
40
35
30
25
20
15
10
5
Probable
Definite
Age-standardised mortality rate per million
0
70 72 74 76 78 80 82 84 86 88 90 92 94 96 98 00 02 04
Number of cases
Mortality rates were calculated using the Australian Bureau of
Statistics 2000 resident population estimates for Australia.
was 1.19 deaths per million persons which is similar
to the rates reported by other countries undertaking
prospective ascertainment. 4
Of the 455 sporadic cases, 53 per cent were female
and 47 per cent were male. This ratio has been consistently
observed and suggests no sex predilection. The
median age of death is 67 years (females, 68 years;
males, 66 years) with a range of 25-89 years. The
median illness duration from onset to death of sporadic
CJD cases is four months (females, 4 months;
males, 3 months); however duration ranges from
0.9 to 60 months. Overall, the 70-74 year age group
had the highest mortality rate from sporadic CJD
with 4.2 cases per million per annum. In females, the
mortality rate peaks in the 65-69 year age group with
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0.0
Age-standardised mortality rate per million
4.8 cases per million per annum, whereas in males,
the maximum rate is 4.1 cases per million per annum
in the 70-74 year age group.
Familial CJD similarly shows no clear sex bias. Of
the 40 cases, 55 per cent were female and 45 per
cent were male. Typically, the duration of disease and
age at death of familial cases is longer and younger
respectively, when compared with sporadic CJD. 4
The median duration of Australian familial cases was
found to be seven months (range, 1.5-192 months)
which is significantly longer than the duration of
sporadic CJD cases (p