タミフル耐性のAソ連型インフルエンザ  欧米で広がる

Aソ連型インフルエンザ タミフル耐性 欧米で広がる
http://www.tokyo-np.co.jp/article/national/news/CK2008020302084700.html
2008年2月3日 東京新聞朝刊
画像 欧州で流行中のAソ連型インフルエンザに、治療薬タミフルが極めて効きにくい耐性ウイルスが広がりつつあると欧州疾病対策センター(ストックホルム)が二日までに発表した。同様の耐性は米国でも検出された。
 Aソ連型は日本でも今冬の流行の中心。今のところ国内で耐性ウイルスは見つかっていないが、国立感染症研究所は「タミフルの使用が多い日本で広がると、治療に大きな影響が出る恐れがある」として、上陸を警戒している。
 欧州専門家チームの速報によると、昨年十一月から今年一月までに欧州十八カ国で分離されたウイルス計四百三十七試料のうち、九カ国の五十九試料(14%)からタミフルへの強い耐性を示す遺伝子変異が検出された。検出率はノルウェーが70%と突出している。米国でも5%で同様の耐性が見つかったという。
 感染研の小田切孝人ウイルス第三部室長によると、日本や韓国、台湾など東アジアでは検出されていない。
 タミフルへの耐性ウイルスはこれまでにもあったが、多くは1%以下と比較的まれで広がりにくく、これほどの高頻度は初めて。耐性は薬を多く使っている環境で発生しやすいが、欧州では通常のインフルエンザにタミフルをほとんど使わないため、自然の突然変異でできたとみられる。患者の症状は通常のインフルエンザと変わりなく、リレンザなど別の薬は有効だという。
 世界保健機関(WHO)は先月末、日米欧などの専門家と緊急電話会議を開き、慎重な監視を申し合わせた。
 小田切室長は「これ以上拡大するのかどうかを世界で協調して監視することが重要だが、国内の治療方針を変える必要は当面ない。新型インフルエンザ対策にも特に影響はない」と話している。
------------------------------------------
 この冬、欧州や北米で流行しているインフルエンザにタミフル耐性変異株が出ているとWHOが発表した。
 一般的にはこのタイプの変異は病原性が低く伝染力が低下すると思われてきたため、研究者達は驚いている。優勢な流行株はA/H1N1 だが、変異株は A(H1N1 H274Y)である。標準インフルエンザワクチンはこの変異型にも予防効果がある。ノルウェーで11-12月に75%の割合で変異株が分離されて注意喚起がなされたが、欧州全体でみると5%だった。米国では全体の3.8%だったが、A型(H1N1)の中では6.7%だったという。しかし、タミフルを多数使用している日本での検出がないので、どのようにして抵抗性を獲得したかがまだわからない。
------------------
Mutant Flu Virus Is Found That Resists Popular Drug
http://www.nytimes.com/2008/01/31/health/31flu.html?_r=1&ref=health&oref=slogin

By LAWRENCE K. ALTMAN
Published: January 31, 2008

A small but significant percentage of the main influenza virus causing illness this winter in Europe, Canada and the United States has a mutation that makes it resistant to the anti-influenza drug Tamiflu, the World Health Organization said Wednesday.

Scientists said they were surprised by the finding because they had believed that mutations of this type generally made the virus less potent and less easily spread among people. The predominant influenza virus circulating this winter is influenza A/H1N1. The Tamiflu-resistant form of the virus, known as influenza A(H1N1 H274Y), has been found with varying frequency in various areas of four European countries, Canada and the United States.

There are no immediate plans to recommend changes in the use of Tamiflu, which is also known as oseltamivir, officials from the W.H.O. and the United States said in interviews, because the incidence of the mutant virus is still small. Tamiflu is one of the antiviral drugs used to treat influenza in its early stages.

Nevertheless, officials from the W.H.O., a United Nations agency in Geneva, said they were troubled by the discovery.

“Clearly, this is of global concern, but it is not a global problem now,” Dr. Frederick G. Hayden, an influenza expert at the organization, said in a telephone interview.

The standard influenza vaccine still protects against the mutant virus, said Dr. Hayden and Dr. Alicia Fry, an influenza epidemiologist at the Centers for Disease Control and Prevention in Atlanta.

Norwegian epidemiologists first called attention to the problem last week when they reported that the mutation was present in 12 of 16, or 75 percent, of viruses isolated in that country from patients in the earliest part of the influenza season, in November and December.

The Norwegian rate was the highest among the four European countries ― Britain, Denmark, France and Norway ― that reported the mutant virus. There was no evidence that the 12 cases in Norway were linked to one another.

Over all, the mutant form was found in 19 of the viruses isolated from 148 patients or 13 percent, in a monitoring system that the European Center for Disease Prevention and Control runs in 10 European countries.

The overall percentage fell to 5 if Norway was excluded.

In the United States, the Tamiflu resistant strain was found in 9 of 237, or 3.8 percent of patients from whom influenza type A and B viruses were isolated this winter, and all 9 were in the A(H1N1) category, making them 6.7 percent of those 135 cases, Dr. Fry, said in a telephone interview.

The W.H.O. conducted a teleconference lasting two hours on Tuesday to collect information from experts in a number of countries. The participants agreed that continued close monitoring was needed to collect information on a larger number of patients to determine the frequency, transmission and distribution of the mutant strain as well as its virulence, Dr. Hayden said.

Scientists also want to learn how the resistance developed. It is unlikely to have been from use of Tamiflu, Dr. Hayden said, in part because no cases have been detected in Japan, where the drug is often used in treatment.

----------------------------------------
WHO Reports Tamiflu-Resistant Flu in U.S. and Canada
Mutant Strain Threatens to Breach First Line of Pandemic Defense
http://abcnews.go.com/Health/ColdFlu/wireStory?id=4227416
By Stephanie Nebehay
Feb 1, 2008

GENEVA (Reuters) - The main flu virus circulating in the United States and Canada has shown "elevated resistance" to the antiviral drug Tamiflu, in line with findings in parts of Europe, the World Health Organisation (WHO) said on Friday.

The United Nations agency said it was too early to know what potential there may be for increased Tamiflu resistance in H5N1 avian influenza. It did not change its recommendation that Tamiflu be used to treat human cases of bird flu.

A number of governments have been stockpiling Tamiflu, made by Switzerland's Roche Holding Ag and Gilead Sciences Inc of the United States, for use as a first line of defense in case bird flu sparks a human influenza pandemic.

The WHO said it was investigating the extent of resistance worldwide to Tamiflu, known generically as oseltamivir, in some seasonal H1N1 flu viruses that have a mutation making them "highly resistant."

The U.S. Centers for Disease Control and Prevention has reported a five percent prevalence of resistance to Tamiflu in samples of H1N1 virus tested to date. In Canada, 8 out of 81 samples showed resistance -- more than a 10 percent resistance rate, WHO spokeswoman Sari Setiogi said.

"These preliminary data indicate that oseltamivir resistance in H1N1 viruses is geographically variable but not limited to Europe," the WHO said in a statement.

A preliminary survey issued by the European Centre for Disease Control (ECDC) this week said that of 148 samples of influenza A virus isolated from 10 European countries during November and December, 19 showed signs of resistance to Tamiflu.

Of 16 samples from Norway, 12 tested positive for resistance against Tamiflu, according to the ECDC study.

The new "elevated resistance to oseltamivir" appears limited to seasonal H1N1 viruses, and does not involve H3N2 or influenza B viruses which are also circulating, the WHO said.

"This means that oseltamivir would most likely be ineffective for treating or preventing infections caused by these resistant H1N1 strains, although the drug will be effective against other influenza virus infections," it added.

The WHO said it was contacting national health authorities to determine the extent of resistance to the drug. Neither Japan -- where Tamiflu is widely prescribed for seasonal flu -- nor Hong Kong had seen increased resistance to date, it said.
s New Jaw From Stem Cells

Past studies had found Tamiflu resistance rates ranging from zero to 0.5 percent, according to the U.N. agency.

"The frequency of oseltamivir resistance in H1N1 viruses in the current influenza season is unexpected and the reason why a higher percentage of these viruses are resistant is currently unknown," the WHO said.

Tamiflu has been proposed for treating H5N1 bird flu in humans. Health experts fear that virus, which now mainly affects poultry, could mutate into a form that spreads easily among people and trigger a deadly pandemic.

(Reporting by Stephanie Nebehay, editing by Keith Weir)

Copyright 2008 Reuters News Service. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed.

ブログ気持玉

クリックして気持ちを伝えよう!

ログインしてクリックすれば、自分のブログへのリンクが付きます。

→ログインへ

なるほど(納得、参考になった、ヘー)
驚いた
面白い
ナイス
ガッツ(がんばれ!)
かわいい

気持玉数 : 0

この記事へのコメント

この記事へのトラックバック