Why are there so many listeria recalls lately? A doctor explains what you need to know and what symptoms to look out for.

Out of Deli meat To frozen waffles, Listeria remembers seem to be making headlines more often – but why?

“There are a few reasons why we may be seeing an increase in these contaminations, including a more complicated food supply chain,” explains Dr. Céline Gounder, CBS News medical staff writer and public health editor at KFF Health News.

“Every step of food processing presents the possibility of contamination. That's number one. Consumers want ready-to-eat foods, so naturally they become more processed,” she said on “CBS Mornings.”

Furthermore: “We have better tests. In the past, we may not have known what was making you sick. Now we can actually test, detect and tell you what made you sick.”

Although these recalls appear to be more common, they should not be ignored. Listeria can cause serious illness and even be fatal.

“You can develop a pretty serious illness, including meningitis if it spreads to the spinal cord, or sepsis, where the listeria can get into your bloodstream and damage your organs,” Gounder said.

So if you have a product a callback listit's best to throw it away.

“It’s not worth the risk. That could be fatal. So just throw away everything that’s on that recall list,” she said.

Listeria symptoms

Listeria infections are caused by eating foods contaminated with the bacteria Listeria monocytogenes. Symptoms to watch out for include headaches, fever, changes in your mental status, difficulty walking, and even seizures.

The Centers for Disease Control and Prevention warns that people may also experience a stiff neck and flu-like symptoms such as muscle aches and fatigue.

Some people are also at higher risk of severe cases, including pregnant women, newborns, adults age 65 and older, and people with weakened immune systems.

“Some of the foods we consider high-risk — and why we tell pregnant women not to eat them, for example — are deli meats and soft cheeses,” Gounder said. “There is a very high risk of contamination with these foods.”

Does heat or cooking kill listeria?

Thoroughly cooking or reheating food can kill listeria, but Gounder notes, “You have to cook things at a high enough temperature.”

The CDC recommends reheating deli meats, cold cuts, hot dogs, and fermented or dry sausages to 165°F or until steaming hot. The same goes for pasteurized soft cheeses and fine-cut cheeses – heat to an internal temperature of 165°F before eating.

“Freezing does not kill bacteria like listeria. It’s a very robust bacterium,” Gounder said. Even cooling does not kill listeria.

How does listeria spread?

Gounder explains that listeria is most commonly spread through food, but it can also spread through cross-contamination.

“It could come from other foods, it could be contaminated equipment or surfaces. We find listeria in soil and water. So there are a lot of different ways they can get into a frozen waffle (for example),” she said.

If a recalled product is in your refrigerator, freezer, or elsewhere in your kitchen, it is important to disinfect those surfaces to prevent further contamination.

Treatment of listeria

Treatment depends on the severity of the disease. It may contain antibiotics or fluids to prevent dehydration. See a doctor if you suspect you are infected.