The current outbreak pales in comparison to some of the biggest food-safety incidents in United States history.
So far, an outbreak of Salmonella linked to peanut butter has sickened 35 people in 19 states and prompted a recall of hundreds of products that contain peanut butter, including cookies, crackers and ice cream.
That may sound like a big deal, but the current outbreak pales in comparison to some of the biggest food-safety incidents in United States history.
Last year, for example, cantaloupe tainted with Listeria sickened 147 people in 28 states and caused 33 deaths. Other major outbreaks and recalls have involved ground beef, spinach and sprouts.
And this isn't the first or most dramatic example of peanut butter's ability to cause major problems. In 2008 and 2009, Salmonella in products distributed by the Peanut Corporation of America sickened more than 700 people in 46 states, causing 9 deaths and leading to the recall of nearly 4,000 products made by more than 350 companies.
Despite major efforts by governmental organizations to track down the sources of outbreaks alongside significant reductions in rates of most kinds of food-borne illnesses, these kinds of ongoing problems point out the complexities of our food-distribution system and the many steps along the way where dangerous bacteria can sneak in.
Often, small companies in rural America produce ingredients that end up in tons of different products around the country. At the same time, foods enter our grocery stores from far-away places, where regulations may be lacking.
"One of the things that has happened in the last 10 to 20 years is that we rely on food systems around the world -- food produced in Vietnam, China, Central America, Mexico -- and we need it to be produced safely in those places because it will wind up on your plate in short order," said Ian Williams, chief of the Center for Disease Control and Prevention's Outbreak Response and Prevention Branch in Atlanta.
"I think the take-home message is that our food supply is big and it's complicated," he said, "And we really need to focus on this idea of food safety as not just at the table but all the way from farm to fork."
Peanut butter is a perfect example of a product that can become contaminated in any number of steps along its path from agricultural field to jar of creamy spread.
Peanuts grow in the ground, for one thing, which is filled with dirt that can easily accumulate bacteria, including Salmonella and E. Coli O157:H7 from contaminated water or animal manure. Roasting can kill those pathogens, but only if done at the right temperature for long enough period of time. Even then, companies need to be careful to keep peanuts clean after the cooking is done.
If Salmonella manage to survive processing, they will live happily for years inside peanut butter's ideal mix of sugar, fat and salt, Williams said. In one outbreak linked to a cereal factory, Salmonella were found that had been living in the factory's walls for decades.
Salmonella don't actually grow inside peanut butter. Instead, they lie in wait until they get deposited in a growth-inducing environment, like the human gut. There, they can "wake up" and cause illnesses, especially in the very young, the elderly and people with compromised immune systems.
In years with drought stress, peanut shells develop extra cracks that allow bacteria to sneak in, added Robert Buchanan, director of the Center for Food Safety and Security Systems at the University of Maryland, College Park. Peanut butter can also cause major headaches because it ends up as an ingredient in so many different kinds of foods.
Cantaloupe is another repeat offender, in part because it's hard to wash the fruit's rough surface and farms don't always comply correctly with disinfecting and storage guidelines. When consumers cut a contaminated melon, the knife deposits bacteria on the fruit's flesh, and those pathogens will grow rapidly if the fruit is left on the counter for any period of time.
Last year's cantaloupe outbreak was particularly concerning because it involved Listeria, a bacteria that kills people and causes miscarriages at relatively high rates compared to other types of food-borne pathogens.
Ground beef has caused some high-profile outbreaks, as well, including the Jack-in-the-Box recall of 1993, which sickened hundreds and killed four children. One problem with ground beef is that it often contains meat from multiple cows. It's also a good breeding ground for E. Coli O157:H7, which can cause severe illnesses, including kidney failure.
Spinach has caused plenty of problems -- including a 2006 outbreak of E. Coli that killed three people and made about 200 sick -- as have sprouts. Because of the way sprouts are grown, bacteria can easily get into the seeds, making it impossible to wash them off. High heat would kill the pathogens, but few recipes call for cooked sprouts.
Major recalls often alarm people, but recalls aren't always associated with illnesses or outbreaks, Buchanan said. Sometimes, routine testing turns up bacteria or unlisted allergens in a product, leading a company to initiate a recall to stay on the safe side.
In 2008, for example, Kraft Foods recalled 2.8 million pounds of chicken because of potential Listeria contamination, even though not a single related illness was reported.
Often, though, outbreaks and recalls go together, like the 2010 Salmonella contamination in eggs, which made some 1,600 people ill and led Hillendale farms to call back hundreds of millions of eggs.
As people move away from processed foods and towards more fresh produce, the risk of bacterial contamination tends to rise, Buchanan said, simply because farms are -- by definition -- not pristine environments.
Educating yourself about food safety can help.
"You have to buy food from reputable dealers," Buchanan said. "Store them appropriately, eat a varied diet and when they get to the end of their shelf life, throw things out."