Here’s what you need to know.

• Listeria is a foodborne bacteria that causes illness and, in extreme cases, death.
• The meat was packaged between May 10 and July 29 at a plant in Jarratt, Va. Boar’s Head said it has since paused some operations at the plant. The recalled products have “sell by” dates ranging from July 29 to Oct. 17.
• Customers with recalled meat should throw it away or return it for a full refund, Boar’s Head wrote online. The complete list can be found in PDF form here and on the Boar’s Head website here.
• The listeria outbreak killed two people and hospitalized 33 as it spread across 13 states, the Centers for Disease Control and Prevention said. Listeria outbreaks are especially dangerous for people who are elderly or pregnant.

The CDC began investigating an ongoing listeria outbreak on July 19. The USDA announced Friday the first recall of more than 200,000 pounds of Boar’s Head liverwurst possibly contaminated with listeria.

That initial recall came after the Maryland Department of Health and Baltimore City Health Department collected an unopened liverwurst package from a retail store for testing as part of the wider investigation. The tests showed it contained an outbreak strain of listeria affecting liverwurst and other Boar’s Head products.

On its website, Boar’s Head wrote that the USDA told the company on July 29 the Strassburger brand of liverwurst from the Virginia plant was linked to the national outbreak.

“We have also decided to pause ready-to-eat operations at this facility until further notice. As a company that prioritizes safety and quality, we believe it is the right thing to do,” a note on the company’s website said.

The products being recalled were sent to stores across the United States, as well as the Cayman Islands, the Dominican Republic, Mexico and Panama. The products bear the labels “EST. 12612” or “P-12612” inside the USDA mark of inspection on the product labels, according to the agency. The recalled items include ham, hot dogs, bologna and bacon.

Customers can contact the recall hotline at 888-266-7913 with questions or concerns.

“We deeply regret that our liverwurst products were found to be adulterated with Listeria monocytogenes,” the company said.

“No words can fully express our sympathies and the sincere and deep hurt we feel for the families that have suffered losses and others who endured illness,” Boar’s Head wrote on its website.

Boar’s Head was founded in 1905 in New York City and has become synonymous with deli meat and cheese in America.

Listeria is short for Listeria monocytogenes. Listeriosis is the bacterial sickness that makes people ill and can be fatal.

Every year about 1,600 people get sick from listeria and about 260 die, the CDC reports. Listeriosis ranks third on the list of foodborne illnesses that cause death in the United States.

Listeriosis can’t be transmitted from one person to another unless a pregnant person passes it on to their fetus, according to the Cleveland Clinic.

People with listeriosis report having flu-like symptoms along with headache, stiff neck, confusion, loss of balance and convulsions, CDC officials said.

Symptoms of a severe case usually start within two weeks of eating contaminated food, but symptoms could present anywhere between the same day and 10 weeks after ingesting the bacteria, according to the agency.

Listeria, an intracellular pathogen, can go through gut lining and into blood. Then listeria in the blood can pass the brain barrier, causing serious infections.

Those who are pregnant are 10 times more likely to get a listeria infection because of increased progesterone levels that make it easier for intracellular microorganisms such as listeria to attack, research shows.

The elderly, according to the CDC, are more susceptible because their immune systems aren’t robust enough to identify and eliminate harmful germs. Americans ages 65 or older are four times more likely to deal with listeria infections.

The CDC recommends people see a health-care provider about foodborne illness if they have severe symptoms such as:

• Bloody diarrhea.
• An oral temperature above 102 degrees Fahrenheit.
• Frequent vomiting that prevents keeping liquids down, which can lead to dehydration.
• Signs of dehydration, including little or no urination, a very dry mouth/throat, feeling dizzy when standing up.
• Diarrhea that lasts more than three days.

Staff members at the Mayo Clinic write that symptoms of a listeria infection in a newborn can be subtle but include:

• Little interest in feeding.
• Irritability.
• Fever.
• Vomiting.
• Difficulty breathing.