Tyson recalls 8.5 million pounds of chicken products due to possible listeria contamination

Government agencies such as local and state health departments, the Food and Drug Administration, the USDA's Food and Safety Inspection Service and the CDC are using better technology to identify, track and contain outbreaks. The FDA oversees all food inspection programs. Meat, poultry, dairy and produce are regulated by the Agriculture Department. Once produce is processed into something like apple juice or banana chips, it is also regulated by the FDA.

"The interesting thing about these bacteria is that they mutate very quickly, which is a great thing for disease detectives," said Jory Lange, a Houston-based attorney who specializes in food safety cases. "Because of that rapid mutation, there's a genetic fingerprint that makes it easier to trace."

But that doesn't mean authorities necessarily know the full extent of a problem. For every one reported case, there are 20 unreported ones, Lange said.

"The reason that's so concerning (is that) without identifying the problem, we can't fix it," he said. "If we can't fix the problem, then we may have someone get sick next month."

There's no way to produce an absolutely safe food, experts say. But consumers can be more diligent about cooking meat to the recommended temperatures, keeping their hands and food preparation spaces clean, refrigerating food and being careful not to not cross-contaminate raw meat and poultry with ready-to-eat food.

Decades ago, the path from farm to kitchen table was much shorter and more local. Today, food that at one time wasn't available in certain seasons now is, making the path to consumer's tables longer, more complicated and rife with opportunities for contamination. Also, consumers are demanding a greater variety of easier-to-prepare and ready-to-eat foods that despite being fresh, have a longer road to the grocery store.

Take, for example, out-of-season packaged, pre-washed produce. It's gone through several steps - from the field to the processor, the packager, the distributor and then the grocer, with the possibility of contamination at each step.

"Fifty years ago you would have gotten lettuce from a farmer in your state, now it's coming from California and Arizona on a much larger scale," said Matthew Jon Stasiewicz, an assistant professor of applied food safety at the University of Illinois at Urbana-Champaign. 

It's not just coming from farther away, it's coming from fewer and larger distributors.

"When you get food on a larger scale it's not inherently any riskier, but if there's a problem the potential harm is magnified," Stasiewicz said. 

Tracing the food's path to the consumer's mouth is an active area of research. Traditionally, a foodborne illness diagnosis (determined by a stool sample) is reported to local and state health departments that work with the CDC try to drill down to the source of the pathogen.

Increasingly, experts are using a tool called "genome sequencing," which uses the DNA fingerprint of the food to help determine its source. A national database at the CDC known as PulseNet uses that DNA fingerprint to link illnesses to one another and try to determine the source of the outbreak.

The challenge is that experts can't narrow down exactly where the contamination began - the field, the packing and processing plants or the grocery store. New technologies are being developed to make it easier and quicker to track food from the field to the grocery store.

Yes. The romaine lettuce outbreak that began last year has hospitalized 89 people and killed five since it was first reported by the CDC in April.

Yes. The Food Safety Modernization Act, enacted in 2011, requires food producers to create better safety measures. But some experts say it's not comprehensive. "We have not implemented a system that allows us to trace back to the farm level," said Jaydee Hanson, senior policy analyst at the Center for Food Safety. 

Currently companies are only required to report where they obtained a food product and the customer for their product, not the entire distribution process.

"Food is something that can get contaminated at any step of the process," said Lange. "One plant and one fruit ... if you have a problem, that problem can spread."