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Wave 3 Start Signaled By H1N1 Increases in North Carolina

Recombinomics Commentary 08:30

February 05, 2010



The latest data from the North Carolina website indicates the frequency of samples testing positive for H1N1 has risen to 25% (see Figure 2 ) from a low of 8% in December. The frequency has not been at 25% since mid-November. This clear upswing in H1N1 detection is consistent with recent comments on increases on college campuses in North Carolina and reports of more severe cases at UNC Medical Center at Chapel Hill. This rise signals the start of wave three.Flu levels in North Carolina have been a concern because of the fatal cluster at Duke Medical Center last October. Tamiflu resistant H1N1 was transmitted patient to patient and at least 3 of the patients died. Recently released sequences from North Carolina indicate five patients were Tamiflu resistant and had the rare HA marker of Y233H. Moreover, 3 of the HA sequences had D225G or D225N , demonstrating transmission of the receptor binding domain changes strongly linked to fatal cases. The presence of D225G/N in the Duke death cluster was not disclosed in a WHO report on the outbreak, or in subsequent reports on D225G by the ECDC or WHO . In addition to these three cases, another isolate collected in the same time frame, but matching the sub-clade from Ukraine also had D225G , signaling significant levels of D225G in the area.The increases in D225G/N in North Carolina has led to concerns that D225G/N will be more common in a third wave because of its linkage to a low reactor status designed by Mill Hill, as well as an increase infrequency of D225G/N reports, with highest frequencies being reported in Ukraine and Russia.Moreover, last week’s CDC report had a spike in Pneumonia and Influenza deaths to 8.2%. The upcoming week 4 report will have the rate at 8.1%, confirming that the spike higher was not due to anomalies associate with holidays. Moreover, the upcoming week 4 report will have 9 pediatric deaths, including 6 in California, once again raising concerns that the severity and lethality of recent H1N1 is higher in 2010 than 2009.Sequence data on H1N1 from area hospitals and recently detected cases in North Carolina would be useful.