PDF file - Department of Health and Ageing

Influenza Surveillance in Victoria, 2005
Annual report
Figure 4. Respiratory viruses detected from
sentinel patients with influenza-like illness,
Victoria, 2005
Figure 6. Laboratory confirmed influenza,
Victoria, 2005, by age group and notification
source
180
100
160
156
90
Non-GPSS
Number of specimens
140
120
100
80
60
40
20
0
26
9
Influenza A Influenza B RSV Adenovirus Picornavirus Parainfluenza
virus
Respiratory virus detected
4
45
10
Number of notified cases
80
70
60
50
40
30
20
10
0
0-4
5-9
10-14
15-19
20-24
25-29
30-34
35-39
40-44
45-49
50-54
55-59
60-64
Age group (years)
65-69
GPSS
70-74
75-79
80-84
85+
GPSS
General practice sentinel surveillance.
There was a sharper and later peak in infl uenza
type A notifi cations from the general practitioner
sentinel surveillance compared to other notifi cations
(Figure 5). Relatively few notifications of laboratory
confi rmed infl uenza were received outside
the GP sentinel surveillance period; 27 cases from
1 January to 1 May and 13 cases from 3 October
to 30 November. Only one outbreak of infl uenza
was notifi ed in the year up to 30 November 2005.
Reported in January, it occurred in an aged care
facility with 19 people ill, of whom seven had laboratory
confi rmed infl uenza.
Figure 5. Laboratory confirmed influenza,
Victoria, 2005, by type and notification source
Number of notifications
40
35
30
25
20
15
10
5
0
Non GPSS type A
Non GPSS type B
GPSS type A
GPSS type B
18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39
Surveillance week
Melbourne Medical Locum Service
During the surveillance period from week 18 to 39,
MMLS recorded a total of 26,775 consultations of
which 317 (1.2%) were for an ILI. The average ILI
per 1,000 consultations was 11.8. Figure 2 shows
a comparison of ILI rates for the infl uenza season
between metropolitan and rural sentinel surveillance
and MMLS data. MMLS surveillance continues all
year and demonstrated a decline in ILI rates to
below 2.0 ILI per 1,000 consultations by week 41.
Other influenza related studies
The evaluation of infl uenza surveillance was completed
in 2005 and concluded with fi ve recommendations
summarised in the Box.
The review of relevant available emergency department
and hospital admission data concluded that,
while these data accurately refl ected ILI activity in
the community, they were not available in a timely
fashion as currently collected, reviewed and made
available. Each of the fi ve data sources had different
utilities. All contributed to describing inter-pandemic
infl uenza seasonal activity but MMLS surveillance
was the most effi cient and could be managed with
minimal extra resources, although it did not provide
specimens for viral testing. 6
GPSS
General practice sentinel surveillance.
Discussion
There was a marked difference in the age distribution
of laboratory confi rmed influenza notifi cations
from general practitioner sentinel surveillance compared
to other notifi cation sources (Figure 6). Nearly
one in four cases notifi ed from non-sentinel practice
surveillance was aged less than fi ve years and there
was a higher proportion of cases aged 65 years or
older among non-sentinel surveillance notifi cations.
As measured by ILI rates from the GP Sentinel
Surveillance Scheme, infl uenza activity in 2005
remained within the normal seasonal level with a
well-defi ned peak of 13.1 ILI per 1,000 consultations
during July. Although the initial increase in ILI
activity occurred earlier for both sentinel and MMLS
surveillance than for laboratory notifi cations, the
CDI Vol 30 No 1 2006 141