Influenza --Tracking
Tracking Influenza in Wisconsin
How do you keep track of influenza in
Wisconsin?
Wisconsin monitors influenza activity in several
ways:
- Voluntary submission of isolates by clinical
virology laboratories to the Wisconsin State Laboratory of Hygiene
(exit DHFS).
- Voluntary reporting by virology laboratories
that participate in the Wisconsin Laboratory Information Network (LIN) of
positive test results and total number of respiratory virus
specimens tested.
- Voluntary reporting by a statewide network
of sentinel clinicians of the number of patients presenting with
influenza-like illness (ILI) and the total number of patient visits
by age group each week. This reporting occurs year-round.
- Voluntary reporting of influenza outbreaks
in long-term care facilities, schools and other congregate settings.
Do all cases of influenza in the state get reported?
No – many cases are never reported because
influenza is not a reportable disease in Wisconsin. We do not attempt to track –
or get reports on – all cases. Most cases are never
reported to anyone, since most people with influenza never see a doctor
about their illness – and many of those who do are never tested.
Even if it were possible to track all cases of influenza in the state, it
wouldn’t be useful to do so. Influenza is so common during the winter months
that we could never actively investigate all of the cases reported to
us. We would simply be “counting cases” – and that wouldn’t help
us protect the health of the public. Because
some providers actively test for influenza and others do not, counting
the number of cases would not be a reliable way to track influenza.
Why aren't there more confirmed
cases of influenza?
Although confirmed cases may provide a rough indication
of activity, that's not the primary reason we keep track of them.
Confirmed cases allow us to: (1) determine when we first started to see
influenza activity each year (the "first influenza case of the
season"); and (2) determine what strains of influenza are
circulating in any given year.
That's the main reason we confirm cases in the lab-
finding out what kind of influenza is around, and whether the current
vaccine protects against it. Only a tiny fraction of all cases are
ever confirmed in our lab.
Influenza Home Page
Last Revised: October 19, 2007
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