Well, bad new for all you web surfers out there that depend upon the standby peanut butter and jelly sandwhiches to keep you going. ConAgra Foods told consumers to chunk certain jars of Peter Pan and Great Value peanut butter after a salmonella a had 300 people in 39 states hurling up their guts. Seriously now, lids of jars with product codes beginning 2111 can be returned to ConAgra for a refund, the company said.

How exactly the salmonella entered the peanut butter remains under investigation, said Dr. Mike Lynch, an epidemiologist at the Centers for Disease Control and Prevention. Officials at the centers said the outbreak was thought to be the first from peanut butter. The most cases were reported in Missouri, New York, Pennsylvania, Tennessee and Virginia. About 20 percent of the patients were hospitalized, and there were no deaths, Dr. Lynch said.

ConAgra officials said they were unsure why the C.D.C. had identified peanut butter as the source of the problem. A spokesman for the company, Chris Kircher, said that tests of the peanut butter and factory were negative but that it closed the plant to investigate. The company has not said how much peanut butter is being recalled.

The Peter Pan brand is sold in 10 varieties, the ConAgra Web site says. Great Value peanut butter, which other companies also manufacture, is a Wal-Mart brand. The recall does not affect Great Value peanut butter made by other companies, the Food and Drug Administration said.

Other states reporting cases are Alaska, Alabama, Arkansas, Arizona, California, Colorado, Connecticut, Georgia, Iowa, Illinois, Indiana, Kansas, Kentucky, Massachusetts, Maryland, Maine, Michigan, Minnesota, Mississippi, Montana, North Carolina, Nebraska, New Jersey, New Mexico, Ohio, Oklahoma, Oregon, South Carolina, South Dakota, Texas, Vermont, Washington, Wisconsin and West Virginia.

Salmonella infection is known each year to sicken 40,000 people in the United States, according to the disease centers. Salmonellosis, as the infection is known, kills about 600 people annually. The symptoms can include diarrhea, fever, dehydration, abdominal pain and vomiting.