Influenza Surveillance In Saskatchewan

Ken Brandt

Manager, Virology Section

Provincial Laboratory

Regina, Saskatchewan

Purpose

The early detection of Influenza A and B in the province

The early detection of novel influenza strains in the province

Saskatchewan has had an influenza surveillance program for over thirty years

Now part of Flu Watch – the Federal/Provincial influenza surveillance program

Saskatchewan’s program is unique

- the Flu Watch program is run out of

the Provincial Laboratory instead of

being run by the provincial epidemiologist

- we recruit our own surveillance

physicians not NARES

Currently have 13 sentinel physicians that geographically cover all areas of the province

They report influenza-like illness (ILI) on a weekly basis

Requested to send 2 NPS specimens each week on patients they see with ILI

ILI definition for 2004 – 2005

Acute onset of respiratory illness withfever and cough and with one or more of the following – sore throat, arthralgia, myalgia, or prostration which could be due to influenza virus. In children under 5, gastrointestinal symptoms may also be present. In patients under 5 or 65 and older, fever may not be prominent.

Problems with ILI

- sentinel physicians may not see any patients with ILI on their recording day

- symptoms seen may not match ILI definition or the symptoms shown may be due to other viruses

For example:- 68 year old male presents with cough and

nasal congestion

- 15 year old male with fever, cough, sore

throat and flu-like symptoms

- 10 year old male with fever, cough, sore

throat and nausea/vomiting

Which one has influenza?

- 68 year old male presents with cough and nasal congestion = Influenza A

- 15 year old male with fever, cough, sore throat and flu-like symptoms =

Parainfluenza 2

- 10 year old male with fever, cough, sore throat and nausea/vomiting =

Adenovirus

Laboratory confirmed cases of influenza from the clinical specimens submitted to us are

the main source of data that we use in Saskatchewan for Flu Watch

- advantage over ILI is that you know exactly what you are dealing with

The number of clinical specimens received on a daily basis from all areas of the province provide a more accurate picture of respiratory virus activity in the province than weekly ILI data

Direct correlation with the number of incoming specimens and influenza positives

Influenza 2003-2004

0100200300400500

Sept.

26

Oct. 17

Nov.

7

Nov.

28

Dec. 1

9Ja

n. 9

Date received

Tota

ls specimens

positives

Therefore, in reality, we do not just have 13 surveillance physicians but every physician submitting a specimen becomes a surveillance physician

Because we routinely screen for influenza on all respiratory specimens no matter what month we are providing year round surveillance

Respiratory specimen protocol:

- Direct DFA using Chemicon’s Simulfluor Respiratory screen – detects the presence of 7 respiratory viruses including Influenza A, Influenza B, Parainfluenza 1,2 and 3, RSV and Adenovirus

- Tissue culture isolation (PMK, MDCK, HP2)

- Molecular testing

HAI is done on all tissue culture positive

Influenza A isolates to determine strain –

i.e. H1N1 or H3N2

• Critical - if the isolate is not H1N1 or H3N2 it is sent to our molecular lab for further testing as it may be a novel or pandemic strain

Additional data used to determine influenza activity in the province:

- reports of school and work site absenteeism

- confirmed outbreaks in hospitals, LTC facilities

In conclusion:

- In Saskatchewan, influenza surveillance or Flu Watch is laboratory based

- The main source of data for influenza activity is lab confirmed positive influenza tests

- other sources of data include number of incoming respiratory specimens, ILI data from surveillance physicians, reports of school and work site absenteeism and outbreaks

- strain identification is critical in providing timely information for pandemic planning