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Published Date: 2011-09-13 17:51:48
Subject: PRO/AH> Influenza (54): (PA) swine-origin H3N2 reassortant, comment
Archive Number: 20110913.2789

INFLUENZA (54): (PENNSYLVANIA), SWINE-ORIGIN H3N2 REASSORTANT, COMMENT
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Date: Mon 12 Sep 2011
From: James Wilson <jim.wilson@praecipiointernational.org> [edited]

A comment in response to: "Influenza (52): (PA), swine-origin H3N2
reassortant, 3 cases 20110906.2723"
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What would be far more helpful to ProMED readers who are clinically
practicing are specific recommendations for when to report such cases
and how to distinguish them clinically (or epidemiologically) from
other cases of influenza. This appears to be especially problematic
when this virus does not appear to produce clinical findings much
different from seasonal influenza.

Given swine H3N2 has been circulating for years now, it would probably
be helpful to understand in this instance how these cases came to the
attention of the PA Dept. of Agriculture. Was there an influenza
surveillance system already in place where virus samples were being
collected passively and sequenced? If so, this does not bode well for
clinically-based recognition of "unusual" morbidity versus mortality,
given the number of areas in the country without such capabilities.
Thus, these warnings of swine H3N2/pandemic H1N1 recombinants have
limited practical value for the reporting base that public health
depends on: the clinicians.

As a nation (and indeed, the world), this places us in a "fall-back"
position of waiting for an abrupt, unusual influx of morbidity into
the healthcare infrastructure, with the attendant occasional high
morbidity/mortality seen in the ICU setting. In such acute
presentations, as we have seen with the pandemics of 1889, 1918, 1957,
1968, other seasons of "bad influenza (vaccine drift)," and the recent
pandemic of 2009, human recognition of such signature patterns is NOT
based on laboratory surveillance. Indeed, such bias prevented rapid
recognition of the 2009 pandemic influenza signature patterns in
Mexico in early 2009 and the surprised, reactive response observed.
Minimization of surprise is essential for a well-considered response.

What I am attempting to highlight here is the operational difference
between laboratory surveillance that highlights a potential threat of
public health significance and event-based surveillance that
highlights the "so what"/verification of significance. Finding a way
to bridge different surveillance approaches that feed into a proactive
warning system remains an essential need for our country and, indeed,
the world.

--
James M. Wilson V, MD
Executive Director
Praecipio International
Washington-Houston-Port au Prince
<jim.wilson@praecipiointernational.org>

[ProMED-mail welcomes the opportunity to communicate James Wilson's
observations and questions to a wider readership. This moderator does
not have information to contribute at this stage. Interested readers
should communicate directly with Dr. Wilson, and any outcomes may be
posted. - Mod.CP]

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