H1N1 Swine Flu Tamiflu Resistance Spreads To Mississippi
Recombinomics.com
December 23, 2013
The CDC released a series of H1N1 sequences, which were largely from the first three weeks of November. Included were two sequences with H274Y, which correlates with the two Tamiflu resistance cases announce in the week 47 FluView. One of these sequences, A/Louisiana/13/2013 is closely related to the three earlier resistant sequences from Louisiana (A/Louisiana/07/2013, A/Louisiana/08/2013, A/Louisiana/10/2013), which signaled clonal expansion and evolutionary fitness.
However, a sequence, A/Mississippi/11/2013, from a November 4 collection (29M) signal clonal expansion outside of Louisiana and raises concerns that the resistance is spreading in the south, where the highest levels of ILI were reported in the week 50 FluView (Texas, Louisiana, Mississippi, Alabama). Texas has reported sensitivity in 8 H1N1 cases in the week 47 report, but the subsequent reports have not cited test results for any more recent cases.
The week 50 Fluview as well as the weekly report for Texas, indicated the level of H1N1 was approaching 100% (the reported frequency was 94% and 95%, respectively, which was a artificially reduced due to the low sensitivity of the rapid test for H1N1).
The spread to Mississippi raises concerns that H274Y was also spread to eastern Texas, where sever and fatal H1N1 cases have led to an alert as well as concerns that H1N1 in eastern Texas may be more virulent due to acquisition of D225G and/or D225N. The latest CDC release included the only sequence from Texas this season, A/Texas/36/2013.
Media reports have indicated that samples from fatal cases in Conroe were sent to the CDC last week, and it is likely that samples from the 6 confirmed fatalities in the Houston area have also been sent to the CDC.
Release of full sequences from fatal or severe cases in Texas would be useful.
