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of Tamiflu Resistant Pandemic
H1N1 in Texas
The above translation adds to the uncertainty associated with the oseltamivir resistance report on the Texas / Mexico border (see map). Since the report cites self-treatment of Tamiflu, it is unclear if and when the resistant cases were treated. In previously announced cases worldwide, five were on prophylactic treatment because of exposure , and at least two developed symptoms on the fifth day of Tamiflu treatment, raising concerns that H274Y was present at reduced levels in these patients and the treatment allowed for the detection of the H274Y, which may be the case for some of the patients on the Texas border.
However a traveler from San Francisco was tested in Hong Kong and had H274Y in the absence of Tamiflu treatment, which may also be the case for some of the patients along the Texas border. More aggressive testing and release of these sequences would be useful.
However, these sequences should be tested more thoroughly for the presence of H274Y as a mixture. A recent report on Relenza resistance (Q136K) indicated the polymorphism was only detected after culture on MDCK cells, indicating the levels in the clinical sample were below detection. In addition to the nine examples in southeast Asia / Australia, which were in the report, a sequence from Nicaragua has been published (see list here) and a mixture from Pennsylvania was published a year ago, although agency reports claim no Relenza resistance in the US in the 2007/2008 season. The Q136K was in patients who were not being treated with Relenza, and more widespread treatment of swine flu patients will likely lead to more detected cases, which is the likely situation for H274Y also.
The failure to provide more concrete information and sequences from the resistant patients along the Texas border increases concerns that resistant pandemic H1N1 is widespread, but grossly under-represented in the limited number of public sequences released at Genbank or GISAID.