The four infected Minnesotans, including one child, became ill between July 10 and July 24. All five have recovered, although one Minnesotan was hospitalized, state officials said. Health officials say they are concerned that it could be the beginning of a much larger outbreak.
Up to 500,000 pounds of suspect meat was sold to Sam's Club in late June, according to officials from the meat processor, Carneco Foods of Columbus, Neb. Company officials said it is impossible to know yet how much of it has been consumed or how much might still be in people's freezers.
In Minnesota, the E. coli infections were linked to meat bought at the Sam's Club stores in White Bear Lake and Eagan. The Wisconsin case of E. coli 0157:H7 was linked to the store in Waukesha.
State health officials said that Sam's Club removed all of the remaining suspect meat from its shelves Tuesday.
While no other cases of infection from the bacteria have been reported, officials say they don't yet know how many of the national discount retailer's 500 stores have sold the meat.
The investigation into the how the meat was contaminated and how far it has spread is just beginning, said Dr. Harry Hull, Minnesota's state epidemiologist.
"There is the potential for this to be much larger," he said.
John Schaller, vice president of operations for Carneco, said that the company is voluntarily recalling three meat products that could be contaminated: ground sirloin patties; ground beef patties with 20 percent fat; and 90-percent-lean ground beef sold in 10-pound packages. They are labeled with lot number 17304-CAR2 and a "best used by" date of Dec. 18, 2004.
The Minnesotans who got sick all bought frozen ground sirloin patties sold under the label "Northern Plains," state health officials said.
Schaller said that all the fresh meat was probably sold long ago.
"But the problem is that anyone can put this in their freezer and eat it six months from now," he said. "We are concerned for anyone who becomes ill."
The meat is not a risk as long as it is cooked to at least 160 degrees Fahrenheit, hot enough to kill the bacteria.
But Hull warned that anyone who handles raw meat can contaminate other uncooked food, such as salad.
The bacteria produce a toxin in people that causes severe or bloody diarrhea and sometimes other serious complications. While most healthy people recover, children and the elderly are at greatest risk, Hull said.
"We do have one or two children who die of E. coli every year in Minnesota," he said.
Ground beef is often the culprit in both salmonella and E. coli outbreaks because the processing mixes the bacteria into large batches of meat, Hull said.
"One contaminated cow can contaminate a lot of beef," he said.
Nationally, the number of food-related E. coli outbreaks is declining, according to the Centers for Disease Control and Prevention (CDC). The agency estimated that between 2002 and 2003 the number of cases dropped 36 percent.
Will Hueston, director of the center for animal health and food safety at the University of Minnesota, said that that's largely because the federal government has imposed tougher regulations on food processors. And many of the larger ones are doing more to stop contamination in their plants, he said.
The U.S. Department of Agriculture estimates that less than 1 percent of all ground beef is contaminated with E. coli.
The previous large E. coli outbreak in Minnesota occurred in 2000 when 43 people, including some from other Midwest states, became sick from hamburger sold at Cub and other grocery stores. About 1 million pounds of meat were recalled.
People who think they may have eaten contaminated meat may call the Minnesota Department of Health at 612-676-5414.
Josephine Marcotty is at firstname.lastname@example.org