Smoked seafood and occasionally produce will cause an outbreak as well. Particularly at risk are pregnant women and their fetuses – listeria can cause miscarriage, stillbirth and newborn death. "Listeria in pregnant women will abort the fetus in 35 percent of cases," Nelken said. 

So how do you know whether you were sickened by something you ate or something else?

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"Food poisoning occurs within six to 24 hours of eating the contaminated food, and sufferers usually begin feeling abdominal pain, nausea and diarrhea in eight to 12 hours," Nelken says.

People at high risk of food poisoning include the very young, very old, pregnant women or immune-compromised individuals, such as those with HIV/AIDS or those undergoing chemotherapy. By avoiding certain types of food – or at least cooking them extremely well – many cases of food poisoning can be avoided. At-risk groups should eschew soft, unpasteurized cheeses, undercooked meats – including sushi, and anything that contains uncooked or undercooked eggs. That means no cake batter, cookie dough, or over-easy or sunny-side-up eggs.