Meat recalls have highlighted an uptick in illnesses. Experts offer several theories why.
The headlines keep coming. Last weekend, Cargill voluntarily recalled nearly 1 million pounds of ground beef linked to possible E. coli contamination, its second recall this year. And Topps Meat Co. in September issued the second-largest recall in U.S. history -- 21.7 million pounds of ground beef -- that put the New Jersey-based meat producer out of business.
Those recalls have added to an uptick in E. coli cases since 2005, after more than a decade of declines. The reasons why are unclear, but experts offer several theories, from varying power of microwave ovens to natural fluctuations in bacteria populations.
"It's too easy to bash industry, to say they're just producing dirty meat," said Michael Osterholm, a former state epidemiologist and a professor in the school of public health at the University of Minnesota. "It's not that straightforward."
This year, more than 30 million pounds of ground beef have been pulled off the market in 18 recalls because of possible E. coli contamination, most of them since June. At least 65 illnesses but no deaths so far have been linked to this year's recalls. In 2006, there were just eight recalls of ground beef.
"E. coli is naturally occurring in animals," said Sarah Klein, a staff attorney at the Center for Science in the Public Interest. "It's not something that's surprising to see. The question is: Why are we seeing so much of it?"
U.S. Department of Agriculture (USDA) Undersecretary Richard Raymond told a House panel last week that the rise in cases may be because of weather patterns, drug resistance or changes in animal feed that have led to unintended stress on animals.
"I think it's starting with the animal's environment," he told the panel. Raymond also told the panel that the USDA has adequate authority to recall unsafe meat, and would oppose legislation to make recalls mandatory.
The recall process currently allows companies to decide whether to recall their products, which Raymond defended as efficient.
E. coli cases climbed steadily in Minnesota through the 1990s before dropping off this decade, falling from a high of 225 people infected in 1996 to 110 in 2004. Case numbers have steadily risen since then, with 147 cases last year, including the death of Carolyn Hawkinson, 73, of Longville. Hers was the state's first E. coli-related death in more than three years.
The widely publicized recalls may feed some of the rise, said Doug Schultz, a spokesman for the state Department of Health, as the outbreaks raise awareness of E. coli and lead to more reporting from consumers and more checking by physicians.
If people learn anything from the most recent cases -- involving spinach, salad mixes and frozen pizzas -- it's that the bacteria can show up in surprising places, said Jeff Bender, an associate professor at the University of Minnesota's College of Veterinary Medicine.
"The bug is very innovative in ways that it is causing infection," he said.
The problem has been compounded in recent years with the rise of microwaveable foods, said Osterholm, the former state epidemiologist. Many consumers don't know the wattage of their microwave ovens, which can vary by model. Low-power models require longer cooking times, otherwise partially cooked foods might contain cold spots where E. coli and other bacteria dwell.
The resurgence of cases may simply reflect E. coli's growth cycle, which, like other bacteria, sees its populations rise and fall every year, Osterholm added.
"The answer to all of this is irradiation," he said, referring to the practice of blasting food at the processing plant with ionizing radiation to kill bacteria. "It's a safe technology."
Federal food regulations allow the irradiation of ground meat and hamburger, but it's not required of meat producers. Irradiated meat must carry a label on its packaging that includes the radura, a green-colored symbol that denotes irradiation. Ingredients lists may also contain the words "irradiated meat."
The federal Centers for Disease Control and Prevention recommend cooking beef to an internal temperature of 160 degrees.