WASHINGTON — It's as if the whole nation just acquired a peanut allergy. As a salmonella outbreak sickens hundreds of people across the country, federal health officials are warning consumers not to eat products containing peanut butter until they get more information about which products are behind the outbreak.

Peanut butter cookies, peanut butter crackers, even cereal that contains peanut butter — it's all off limits until further notice.

The proximate source of the outbreak, according to the Food and Drug Administration, is peanut butter and peanut paste made by the Peanut Corp. of America at its Blakely, Ga., processing plant.

Sound familiar? Once again, a previously innocuous food product is being linked to a life-threatening foodborne illness.

In 2006, spinach was pulled off store shelves for a month because some of it contained E. coli.

In 2008, the problem products were tomatoes, which health officials thought were behind a huge salmonella outbreak that sickened hundreds of Americans. And now peanuts are under scrutiny.

As a physician, I am profoundly troubled by this situation. Salmonella, E. coli, campylobacter — national outbreaks of foodborne illnesses are coming fast and furious, and federal officials seem to be scrambling just to warn consumers, let alone head off these problems at the source. Perhaps that's because regulators aren't focusing on the underlying problem.

Salmonella and E. coli are intestinal bacteria. But spinach has no intestine. Neither do tomatoes. And neither do peanuts.

When produce becomes tainted, it's usually because feces from an infected animal contaminated the fertilizer or irrigation water used in the fields. As a recent Pew Commission Report on industrial farm animal production noted, untreated animal waste harboring pathogens contaminates air, water, soil and crops. Farm animal waste was the identified cause of the 2006 spinach E. coli outbreak, according to an investigation by the FDA.

The government must acknowledge that the original source of this salmonella outbreak is not peanuts — it's our out-of-control factory farming system.

Americans now eat more than 1 million animals per hour, and as demand for cheap meat grows, thousands more factory farms, feedlots and other agribusiness operations are popping up across the country. A single factory farm often houses hundreds of thousands of animals and produces as much waste as a small city. In fact, factory farm runoff is the biggest water pollution problem in the United States. And the animal waste in this runoff contains pathogens that can be 10 to 100 times more concentrated than in human waste.

Georgia, home of the accused peanut processing plant, ranks No. 1 in the country in the production of chicken meat and eggs — and also in peanuts. With Georgia's poultry industry raising more than 1.3 billion birds a year in crowded, often unsanitary conditions, it's no surprise that some of the billions of peanuts grown in the state are infected with salmonella and other bacteria. Many counties in Georgia produce both poultry and peanuts, which makes it easy for deadly bacteria to travel through runoff into adjacent fields where peanuts and other crops are grown. But many other parts of the country, from Maryland to California, host huge factory farms, and face similar pollution problems.

I hope policymakers will take immediate action in protecting our food supply and investigate animal agriculture as the original source of this salmonella outbreak. But while we're waiting, consumers can help curtail factory farm pollution by simply opting for meatless meals. If more of us followed a plant-based diet, the number of animals on farms would decrease. This health change would help reduce everyone's risk of foodborne illness. It wouldn't hurt our cholesterol levels either.

Editor's Note: Barnard is a medical doctor, nutrition researcher and president of the Physicians Committee for Responsible Medicine.