A deadly food poisoning outbreak has led to the recall of more than 7 million pounds of popular Boar’s Head deli meats made at a plant in Virginia.

U.S. health officials are investigating the outbreak of the bacteria listeria that began in May. Two people have died and nearly three dozen were hospitalized in 13 states.

Listeria poisoning is caused by a particularly resilient type of bacteria that can survive and grow even during refrigeration, according to the Centers for Disease Control and Prevention.

Listeria: A Hardy Bacteria

Listeria bacteria thrive in moist environments, including soil and water and decaying vegetation and are carried by some animals. The hardy germs are typically spread when food is harvested, processed, transported or stored in places that are contaminated with the bacteria. When the bacteria get into a food processing plant, they can be tough to eradicate.

Outbreak Linked to Deli Meats

Many of the people in the outbreak reported eating meats sliced at grocery store deli counters. During the investigation, listeria was detected in an unopened loaf of Boar's Head liverwurst at a Maryland store; the Agriculture Department said further testing showed the same strain was causing illnesses in people.

Symptoms of Listeria Poisoning

People are sickened with listeria poisoning when they eat foods contaminated with the bacteria. Symptoms can be mild and include fever, muscle aches, nausea, vomiting and diarrhea. More serious illness can include headache, stiff neck, confusion, loss of balance and convulsions.

Listeria Symptoms: A Ticking Time Bomb

Listeria poisoning is tricky, because symptoms can start quickly, within a few hours or days after eating contaminated food. But they also can take weeks or up to three months to show up.

Who Is Most Vulnerable?

Those most vulnerable to getting sick include the very young, people older than 65 and those with weakened immune systems or who are pregnant.

How to Prevent Listeria Contamination

Listeria can survive and grow in food even when it's refrigerated, but the bacteria can be killed by heating foods to “steaming hot,” or 165 degrees Fahrenheit (74 degrees Celsius), the CDC says. People who are most at risk for illness should avoid the products or heat them before eating.

Most deli meats, however, are eaten cold. Because listeria can survive under refrigeration, it’s important to clean and sanitize any surfaces, including refrigerator drawers and shelves, that may have come in contact with the products, the CDC says.

The Recalled Products

Many of the products recalled by Boar's Head are meats meant to be sliced at grocery store deli counters, though some prepackaged meats are included in the recall.

They include liverwurst, ham, beef salami, bologna and other products made at the company's Jarratt, Virginia, plant. The recalled meats carry the plant's number — EST.12612 or P-12612 — inside the USDA mark on the label. The meat was distributed to stores nationwide, as well as to the Cayman Islands, the Dominican Republic, Mexico and Panama.

Consumers should not eat the recalled meats and should discard them or return them to the store for a refund.

The Impact of the Recall on Local Businesses

The recall has had a significant impact on local businesses, especially those that rely on Boar's Head products. Many delis and grocery stores have had to temporarily close their deli counters or remove Boar's Head products from their shelves.

For example, Park Wood Deli in Midland Park, New Jersey, has temporarily stopped selling Boar's Head products. Owner Roger Schnorrbush said he is confident that Boar's Head will take care of the problem and that the deli meat woes will be wrapped up in no time.

Prevention is Key

The listeria outbreak is a reminder of the importance of food safety. Consumers should always check the expiration dates of food products and follow proper food handling practices, such as washing hands and surfaces thoroughly before and after preparing food.

A Call to Action: What You Can Do

The CDC recommends that people who are pregnant, older than 65, or have a weakened immune system avoid eating deli meats altogether. If you do eat deli meats, be sure to heat them to an internal temperature of 165 degrees Fahrenheit (74 degrees Celsius) before eating.

This outbreak is a stark reminder of the importance of food safety. Be sure to check your refrigerator for any recalled products and dispose of them immediately.

The investigation into the listeria outbreak is ongoing, and the CDC and USDA will continue to update the public as new information becomes available. Stay tuned for updates, and be sure to practice food safety at all times.