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zoom RSS 病原性大腸菌による食品安全への脅威/米国

<<   作成日時 : 2010/05/28 23:02   >>

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画像 約20年にわたり、食品産業と当局にとって人々の脅威となる最大のものは、数百人が死亡し数千人が発病、数百万ポンドのハンバーガーやほうれん草のリコールを引き起こした病原性大腸菌であった。病原性大腸菌O157:H7に人々の注意が集まったが、6つの稀なタイプの大腸菌はほとんど無視された。これらのタイプの菌は食品安全への重大な脅威である。
 4月には汚染されたロメイン・レタスにより5州で少なくとも26人が発病し、3人のティーンエイジャーが腎不全となった。連邦政府や産業界は何年もの間危険性を知っていたが、当局は具体的な対応をとってこなかった。3年間、農務省は汚染牛ひき肉の売買を違法とするかどうかを考慮してきた。
 ニューヨーク民主党上院議員Kirsten Gillibrandは、牛挽肉へのこれらの大腸菌混入を違法として食肉産業に検査を義務づける法案を計画している。O157の検査は容易だが、6つの稀なタイプは識別が難しく検査に時間がかかる。医療検査施設でも5%しか診断検査ができない。現在、精肉工場で可能な迅速検査キットを開発している最中である。
 昨年行われた120,000件の検査のうち、約1,000に1つは問題のある細菌で多くはこの6種の細菌である。誰もO157以外を検査しようとしない。
 1993年にO157汚染ハンバーガーにより4人の子供が死亡して、O157を含む牛挽肉の販売が禁止された。牛肉産業は定期的にO157についての検査をしているが、問題の他の6系統についての定期検査はない。予備的なデータでは0.2%に6つの系統種が見つかったという。政府データによれば、すでに禁止されたO157系統は約0.3%で見つかる。しかし、William Marler弁護士が委任した検査では、スーパーの牛挽肉の0.7%から6系統の菌が見つかった。
 CDCによれば、1990-2008年で少なくとも10の食品由来の食中毒発生があったという。2007年のノースダコタでの食中毒は牛挽肉が疑われたが関連性が確認できなかった。
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レタス 大腸菌汚染でリコール/米国 ロメイン・レタス
http://kurie.at.webry.info/201005/article_5.html
サルモネラ汚染のため数千の加工食品がリコール/米国 FDA
http://kurie.at.webry.info/201003/article_7.html
新たなサルモネラ感染食中毒が発生 42州400人/米国
http://kurie.at.webry.info/200901/article_21.html
サルモネラ 1000人以上、最大規模の食物由来流行感染に/米国
http://kurie.at.webry.info/200807/article_23.html
トマトに関連したサルモネラ感染報告の増加/米国
http://kurie.at.webry.info/200806/article_29.html
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In E. Coli Fight, Some Strains Are Largely Ignored
http://www.nytimes.com/2010/05/27/business/27bugs.html
By WILLIAM NEUMAN
Published: May 26, 2010

An onsite lab at the Earthbound Farms facility in San Juan Bautista, Calif.

For nearly two decades, Public Enemy No. 1 for the food industry and its government regulators has been a virulent strain of E. coli bacteria that has killed hundreds of people, sickened thousands and prompted the recall of millions of pounds of hamburger, spinach and other foods.

But as everyone focused on controlling that particular bacterium, known as E. coli O157:H7, the six rarer strains of toxic E. coli were largely ignored.

Collectively, those other strains are now emerging as a serious threat to food safety. In April, romaine lettuce tainted with one of them sickened at least 26 people in five states, including three teenagers who suffered kidney failure.

Although the federal government and the beef and produce industries have known about the risk posed by these other dangerous bacteria for years, regulators have taken few concrete steps to directly address it or even measure the scope of the problem.

For three years, the United States Department of Agriculture has been considering whether to make it illegal to sell ground beef tainted with the six lesser-known E. coli strains, which would give them the same outlaw status as their more famous cousin. The meat industry has resisted the idea, arguing that it takes other steps to keep E. coli out of the beef supply and that no outbreak involving the rarer strains has been definitively tied to beef.

The severity of the April outbreak is spurring a reassessment.

“This is something that we really have to look at,” said Senator Kirsten Gillibrand, Democrat of New York, who plans to introduce a bill that would pre-empt the Agriculture Department by declaring a broad range of disease-causing E. coli to be illegal in ground beef and requiring the meat industry to begin testing for the microbes. “How many people do we have to see die or become seriously ill because of food poisoning?”

The issue will be one of the first faced by President Obama’s nominee to head the department’s food safety division, Dr. Elisabeth Hagen, who is scheduled to testify Thursday in her Senate confirmation hearing.

Part of the problem is that so little is known about the rarer E. coli strains, which have been called the “big six” by public health experts. (The term refers to the fact that, after the O157 strain, these six strains are the most virulent of a group of related E. coli.) Few food companies test their products for the six strains, many doctors do not look for them and only about 5 percent of medical labs are equipped to diagnose them in sick patients.

A physiological quirk of E. coli O157 makes it easy to test for in the lab, and many types of food are screened for it. The other E. coli strains are much harder to identify and testing can be time-consuming. The Agriculture Department has been working to develop tests that could be used in meat plants to rapidly detect the pathogens.

The lettuce linked to the April outbreak tested negative for the more famous form of E. coli, but no one checked it for the other strains, according to the Ohio company that processed it, Freshway Foods. It turned out that the romaine was infected with E. coli O145, one of the more potent of the six strains.

Emily Grabowski, 18, a student from Irondequoit, N.Y., ate some of the lettuce at her college dining hall and ended up in the hospital with kidney failure. Recuperating at home, she wonders now if she could have been spared her ordeal. “If they had tested it and they had caught it,” she said, “I wouldn’t have had the E. coli.”

Earthbound Farm, the nation’s largest producer of organic salad greens, is one of the few companies that does screen for the full range of toxic E. coli, and it has found a worrisome incidence of the rarer strains. Out of 120,000 microbial tests last year, about one in 1,000 showed the presence of unwanted microbes, mostly the six strains.

“No one is looking for non-O157 to the level we are,” said Will Daniels, Earthbound Farm’s senior vice president for food safety. “I believe it is really going to emerge as one of the areas of concern.”

Earthbound Farm was not involved in the April outbreak.

The O157 strain of E. coli is a frightening bug, causing bloody diarrhea and sometimes kidney failure, which can be fatal. Some of the six strains cause less severe illness, but others appear to be just as devastating as the O157.

The toxic E. coli bacteria originate in the guts of cattle, putting the beef industry on the front line. The O157 strain achieved notoriety in 1993 when four children died and hundreds of people were sickened by tainted hamburger sold at Jack in the Box restaurants. The next year, the Agriculture Department made it illegal to sell ground beef containing the O157 bacteria.

The beef industry now routinely tests for the O157 strain, but there is no regular testing for the other six strains.

It is unclear how prevalent the six strains are in ground beef. Preliminary data from a department study found the pathogens in only 0.2 percent of samples. By comparison, the O157 strain already banned shows up in about 0.3 percent of samples, according to other government data.

But tests commissioned by William Marler, a Seattle lawyer who represents victims of food poisoning and has pushed the department to ban more E. coli strains, found the six strains in 0.7 percent of ground beef samples bought at supermarkets.

The E. coli bacteria can be killed by thorough cooking to 160 degrees.

Tracking the impact of the rarer E. coli strains on human health is difficult because few medical labs test for them, and health officials say illnesses caused by them are vastly underreported.

Data from the Centers for Disease Control and Prevention showed at least 10 food-borne outbreaks from 1990 to 2008 involving the six strains, carried in foods like salad or strawberries. Investigators suspected ground beef as the cause of a 2007 outbreak in North Dakota, but the link was not confirmed.

The April outbreak is a signal of a broader problem, said Michael R. Taylor, deputy commissioner for foods at the Food and Drug Administration.

“We need to be developing our tools and abilities to assess” the full range of toxic E. coli, he said. The agency, which regulates produce, is waiting for Congress to pass a law that would greatly expand its food safety authority.

It is not clear how E. coli travels from cattle to produce, but scientists think it may occur through contact with manure, perhaps tracked through fields by wild animals, or through tainted irrigation water.

For its part, the Agriculture Department has said it is reluctant to ban the broader range of E. coli in beef until it has developed tests that can rapidly detect the pathogens. It expects to complete those by the end of 2011 and then study how often the six strains show up in the beef supply.

But an official said the timetable was not rigid. “I don’t want to give the impression that we’re going to wait months and months for these tests, and months and months to see what’s in the beef supply,” said Dr. David Goldman, an assistant administrator for the Office of Public Health Science of the department. “In terms of policy options, it’s not like we have to do one and then the other.”

James H. Hodges, executive vice president of the American Meat Institute, an industry group, said that the industry had put in place many procedures to keep E. coli O157:H7 out of ground beef, like washing carcasses in hot water and lactic acid.

Those steps also work against the other E. coli, Mr. Hodges said, pointing to the lack of outbreaks of illness connected to them. “It certainly tells me that both the government and the industry is targeting the correct organism,” he said.

Dr. Richard Raymond, who was the department’s head of food safety from 2005 to 2008, said he stopped short of banning the rarer E. coli from hamburger because he thought that he would not have been able to defend the decision against industry criticism until rapid tests were developed.

But he said the April outbreak could push regulators to act. “I don’t think the U.S.D.A. wants to see another Jack in the Box,” Dr. Raymond said.

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