NSW Influenza Surveillance Report 28 to 4 July 2008 (Issued 11 July 2008)
Summary
Very little influenza activity has occurred in NSW for the week ending 4 July, 2008.
NSW influenza surveillance
The aim of influenza surveillance is to monitor general trends in influenza rather than the total number of people who are infected each year. The surveillance program has 4 main parts:
1.Influenza-like illness (ILI) presentations to 28 Emergency Departments1
In the week to 4 July, ILI presentations to emergency departments were low (rate 1.7 per 1000 presentations) (Figure 1). A few ED's alert systems have been triggered by increased respiratory attendances, but these have not been confirmed with laboratory testing.
2.Laboratory diagnoses of respiratory infections2
Virology
In the week to 4 July, a fewer number of samples tested positive to influenza (all influenza B) than the previous week. Respiratory syncytial virus (RSV) activity remains elevated which is usual for this time year (Figure 2 &Table 1).
Serology
An increase in samples testing positive for influenza occurred this week. Serology is a less reliable source of current influenza activity and tends to fluctuate from week to week (Table 1).
3. Deaths due to influenza or pneumonia3
In the week to 27 June, the number of deaths classified as pneumonia or influenza increased slightly (all classified as pneumonia), however this increase needs to be constant over a couple of weeks to be significant (see methods). The highest proportion of deaths occurring are in people aged 75 years and over (Figure 3).
4. Outbreaks4
No outbreaks were reported this week.
National influenza activity
Laboratory confirmed influenza notifications have shown a small rise over recent weeks.
Year to date, 58% of influenza laboratory notifications to National Notifiable Disease Surveillance Section have been Influenza Type A, 36% have been Influenza Type B and 6% were untyped (Figure 4). Twelve notifications have been typed as H3 and four have been typed as H1(Department of Health and Ageing).
International activity
There have been no reports of unusual influenza activity in Europe since April.(WHO).
Southern Hemisphere
New Zealand
Local influenza activity was reported by a small number of districts, with mostly influenza A viruses circulating. Influenza B viruses were also detected (WHO).
Table 1. Laboratory reports of respiratory virus infection by DIF, PCR and serology NSW, 24 May - 4 July 2008
|
Public Laboratory Surveillance |
Week ending 30 May (No.pos) |
Week ending 6 June (No.pos) |
Week ending 13 June (No.pos) |
Week ending 20 June (No.pos) |
Week ending 27 June (No.pos) |
Week ending 4 July (No.pos) |
|
Virology specimens tested |
284 | 353 | 295 | 269 | 335 | 309 |
|
Influenza A |
0 | 0 | 0 | 1 | 0 |
0 |
|
Influenza B |
2 | 1 | 0 | 5 | 11 |
2 |
|
Adenovirus |
4 | 3 | 6 | 0 | 6 |
7 |
|
Para flu 1 |
4 | 0 | 1 | 1 | 2 |
0 |
|
Para flu 2 |
1 | 0 | 1 | 0 | 1 |
3 |
|
Para flu 3 |
0 | 0 | 1 | 0 | 1 |
9 |
|
RSV |
72 | 77 | 94 | 74 | 98 |
87 |
|
Rhinovirus |
2 | 0 | 4 | 4 | 3 | 2 |
| Point of care tests | (denominator not available) | 60 | 60 | |||
| Influenza A | 0 | 0 | 0 | 0 | 0 | 0 |
| Influenza B | 0 | 0 | 0 | 0 | 0 | 0 |
| RSV | 8 | 14 | 17 | 12 | 22 |
20 |
|
Serology specimens tested: |
151 | 175 | 138 | 156 | 156 |
196 |
|
Influenza A |
10 | 3 | 3 | 6 | 1 |
4 |
|
Influenza B |
5 | 3 | 2 | 7 | 0 |
2 |
|
Adenovirus |
0 | 0 | 0 | 0 | 0 |
0 |
|
Para flu 1 |
0 | 0 | 0 | 0 | 0 |
1 |
|
Para flu 2 |
1 | 0 | 0 | 0 | 0 |
0 |
|
Para flu 3 |
0 | 0 | 0 | 0 | 0 |
0 |
|
RSV |
0 | 1 | 0 | 0 | 0 |
1 |
|
Rhinovirus |
0 | 0 | 0 | 0 | 0 |
0 |
