Three state public health laboratories perform antiviral resistance testing and report their results to CDC. An additional two oseltamivir resistant 2009 influenza A (H1N1) viruses have been identified by these laboratories, bringing the total number to nine.

The above comments from the latest CDC update (week 34) describe two more cases of oseltamivir resistance in states that do their own antiviral resistance (CA, NY, WI). WI’s week 34 report had no resistance in swine H1N1 and NY has not updated its site since the end of seasonal flu reporting in April, so it is likely that the two new cases are from California. California has already reported resistance in an H1N1 hospitalized case in northern California, and the CDC has not identified a Tamiflu linkage, raising concerns that the H1N1 in this case is evolutionarily fit. Moreover, the first evolutionarily fit pandemic H1N1 identified in Hong Kong was from a traveler from San Francisco, increasing concerns that evolutionarily fit H1N1 with H274Y is circulating in northern California. The latest two cases are also likely form California, and although the week 34 report indicated these new cases had a Tamiflu linkage, the relationship between the collection date of the H274Y positive samples and the start of Tamiflu treatment remains unclear.

These nine cases in the US are in addition to three cases in Japan, three in Hong Kong and at least one each from Denmark, Canada, Thailand, China, and Singapore. Thus, 20 cases have been made public, including at least two were evolutionarily fit.

Source/Full Story @: recombinomics.com
Technorati Tags: oseltamivir, Tamiflu, H1N1

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