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Paradigm Shift Intervention Monitoring
the appearance of 120 suspected cases of H1N1 influenza, the Ministry
of Health in Tamaulipas lit red lights, said the health secretary,
Norberto Treviño García Manzo.
The above translation describes a red alert in Tamaulipas, Mexico due to a spike in suspected H1N1 cases. Tamaulipas shares a northern border with Texas and is east of Chihuahua, raising concerns that the novel H1N1 is rapidly spreading. The concerns are fueled by the proximity of the Chihuahua outbreak, as well as the timing, because influenza activity is usually declining in northern Mexico at this time of the year.
The recently released H1N1 sequences from two fatal cases in Chihuahua raise concerns that the receptor binding domain change, D225N, is transmitting. Anecdotal reports of outbreaks in Central and South America describe the same novel sub-clade and frequent detection of D255N in severe cases.
The D225N is in association with another receptor binding domain change A189T, as well as S165N, which adds a new glycosylation. These additional changes likely contribute to the vaccine failures reported by the US Air Force descriptions of novel H1N1 isolates in personnel and dependents.
These recent reports of H1N1 outbreaks and deaths in countries south of Mexico, including Honduras, El Salvador, and Venezuela at this time of year have significant parallels with the spread of pandemic H1N1 two years ago. However, the frequency of severe and fatal cases is higher in the current outbreak, which is almost certainly linked to the transmission of D225N.
Release of 2011 H1N1 sequences from US patients, as well as severe and fatal cases from the countries listed above, would be useful.