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Momtezuma Tuatara
20-01-09, 05:55 AM
http://mdn.mainichi.jp/mdnnews/national/news/20090117p2a00m0na008000c.html

Tamiflu ineffective against influenza strain spreading in Japan

A strain of influenza that spread across Japan this winter is proving resistant to the influenza medicine Tamiflu, a survey by the Ministry of Health, Labor and Welfare has found.

About one in three influenza patients in Japan are infected with the strain, referred to as Soviet-A. Last winter 2.6 percent of cases were resistant to Tamiflu.

The reason for the sudden increase in Tamiflu-resistant cases is unclear, but it is possible that a strain from overseas was carried to Japan. The ministry has set up a research team to investigate the strain and compile guidelines for treatment.

In the survey, local public health institute data was compiled by the National Institute of Infectious Diseases, which operates under the ministry. Data showed that 303 of the 671 influenza patients had the Hong Kong-A strain, and 243, or about 36 percent, had the Soviet-A strain. The other 125 had B-type influenza.

The Institute separately examined samples of the Soviet-A strain taken from 35 patients in 11 prefectures, and found that Tamiflu was ineffective for 34 of the patients, or 97 percent. Researchers did not find Tamiflu-resistance among patients with Hong Kong-A and B-type influenza.
The Tamiflu-resistant Soviet-A virus spread last winter, mainly in Europe. This winter it has spread worldwide, and has been detected in over 90 percent of areas in Britain and the United States. The U.S. Centers for Disease Control and Prevention announced emergency treatment guidelines last month, permitting the use of the inhalant drug Relenza.
Japan has enough Tamiflu to treat 28 million patients. The drug will also be used to treat a new type of influenza.

"Drug resistance is limited to the Soviet-A strain, and there is no need to review our response to the new type of influenza," a Health, Labor and Welfare Ministry representative said. "Vaccines are thought to be effective against drug-resistant viruses. There is no need to be overly anxious. We want people to take care to carry out preventive measures such as washing their hands and gargling."

Momtezuma Tuatara
20-01-09, 05:57 AM
http://www.recombinomics.com/News/12150804/H274Y_US_98.html

H1N1 Tamiflu Resistance in the United States Increases to 98%
Recombinomics Commentary 13:16
December 15, 2008

Forty-five of 46 influenza A (H1N1) viruses tested were resistant to oseltamivir

Twenty-five influenza A (H1N1) and five influenza A (H3N2) viruses were tested for adamantane resistance. All influenza A (H1N1) viruses were sensitive to the adamantanes. All influenza A (H3N2) viruses tested were resistant to the adamantanes.

Limited data on antiviral resistance, as well as the uncertainty regarding which influenza virus types or subtypes will circulate during the season, make it too early to make an accurate determination of the prevalence of influenza viruses resistance to oseltamivir or the adamantanes (amantadine and rimantadine) nationally or regionally at this time.

The above comments from the week 49 report (http://www.flutrackers.com/forum/showpost.php?p=196051&postcount=182) on influenza in the United States extend and confirm earlier data, and once again highlight the mismatch (http://www.recombinomics.com/News/12080802/Antiviral_Mismatch_US.html)between the frequencies of antiviral resistance in the US, and the CDC recommendations which discourage use of amantadines and encourage oseltamivir.

Currently amantadine resiatnce in H3N2 remains at 100%, while similar frequencies (currently 98%) are found for oseltamivir resistance in H1N1.

Most of the influenza in the US is influenza A 408/507, and most of the influenza A is H1N1 (157/175). Last season the level of osletamivir resistance in the US was closer to 10% because clade 2C was in circulation, which had no oseltamivir resistance, but was 100% amantadine resistant. Moreover, most of the oseltamivir resistance (H274Y) in H1N1 was limited to a specific 2B sub-clade.

However, this 2B (Brisbane/59) sub-clade achieved dominance in the southern hemisphere in 2008, and now represents almost all clade 2B in North America (http://www.recombinomics.com/News/10230801/H274Y_Canada.html) and Europe (http://www.recombinomics.com/News/12100807/H274Y_UK_96.html). Thus, now all tested H1N1 in the US and Europe is amantadine sensitive and oseltamivir resistance.

H3N2 has maintained its resistance to amantadine, and in Europe H3N2 is dominant. However, in the US H1N1 is dominant, so the level of oseltamivir resistance is much higher than amantadine resistance, and the CDC recommendations remain mismatched.

MinorityView
20-01-09, 06:00 AM
Good to know that hand-washing still works. I wonder when someone will patent the technique?