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Commentary
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On Manitoba Cluster Increase trH3N2 Concerns
Recombinomics
Commentary 21:35
December 4, 2010
"(Provincial officials) are saying this is just a common flu, but when people are coughing up blood, this is not a regular flu," Harper said.
Kettner said both people who died had underlying medical problems.
Harper said a 35-year-old woman was the first victim about a week ago, while a man, also about 35, died Thursday. Another woman, whose age is not known, was airlifted to Winnipeg last week, where she is fighting for her life.
The above comments provide additional detail on the H3N2 outbreak in Garden Hill in northern Manitoba, but critical details are missing. Media reports on December 2 did not include the serotype of the first fatality, suggesting characterization has been minimal. Similarly, the serotype for the second case had not been confirmed on December 3, although H3N2 was expected.
However, H3N2 fatalities are usually associated with patients over 65. Indeed, prior to the cases described above, Canada had reported two H3N2 deaths and both were over 65, which historically is the age of more than 90% of H3N2 fatalities. These elderly patients usually have significant chronic conditions that lead to the deaths. The severity of the underlying conditions in the above fatalities is far from clear.
Those under 65 rarely die from seasonal H3N2 and also rarely cough up blood, which has been described for 20 of the cases in northern Manitoba according to media reports, which would presumably include the three and five year old described above.
The ages of the above patients are more closely associated with infections by triple reassortants (TRs) like the pandemic H1N1, or the trH1N1 and trH1N2 described prior to the 2009 H1N1 pandemic, or the trH3N2 cases identified after the pH1N1 pandemic.
The two most recent trH3N2 cases led to a pager alert. Both cases were from states (WI and PA) adjacent to Canada, which was true of the earlier case (MN) in 2010. The ages of the 5 trH3N2 cases in the US were 22M, 12M, 1F, 10 mo M, and 45M, which are similar to the ages of the cases in Manitoba.
The outbreak at Garden Hill has had a dramatic effect on influenza statistics from Manitoba. On week 46 there were only 6 confirmed cases, no antigenically characterized samples, and no hospitalizations or deaths from Manitoba. By week 47 (the most recent reporting week), the confirmed cases jumped to 37, and there was one characterized H3N2 sample and one death (it is unclear if the one characterized sample is the fataility or samples collected earlier).
UPDATE: Week 47 report from Manitoba demonstrates that the on antigenically characterized sample from Manitoba was a week 39 isolate from a child in Norman.
Therefore, more detail on the Garden Hill cases would be useful, including antigenic characterization and sequence data. These data are critical to determine if the H3N2 outbreak in Manitoba are due to seasonal H3N2 or trH3N2.
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