A popular grocery chain in the US is recalling all its liverwurst products on store shelves as they could be infected with listeria, the U.S. Food and Safety Inspection Service has said. The announcement comes as health officials are investigating an outbreak of listeriosis across the country which left two people dead and nearly 40 hospitalized. Boar's Head said some of its deli meat could contain traces of the bacteria L. monocytogenes – commonly found in nature, especially in soil, groundwater, vegetables, and animal feces - which can cause the deadly illness.

Most people get listeriosis from eating contaminated foods.

The Florida-based company said it is recalling more than 103 tons of meat, after issuing warnings to customers not to eat them. According to news reports, some grocery chains have also temporarily closed their delis due to the outbreak.

Boar’s Head said the liverwurst products produced between June 11 and June 17 do have a shelf life of 44 days. However, a few of their products tested positive for listeria after state health officials conducted the test in collaboration with the Baltimore City Health Department as part of a larger investigation into a listeria outbreak.

According to experts, frozen and packaged foods have the highest risk of L. monocytogenes contamination. However, listeriosis can affect almost any improperly handled or prepared food. Experts say the bacteria is unique from many other foodborne illnesses as it survives and even multiplies in low temperatures, including refrigerators and freezers.

L. monocytogenes can multiply to dangerous levels during storage. Food that has spoiled breaks down and develops an unpleasant smell, taste, or change in texture. When L. monocytogenes bacteria contaminate food, the smell, taste, and texture don’t change.

A few common signs and symptoms of listeria, include:

• Fever
• Chills
• Headache
• Upset stomach
• Diarrhoea
• Nausea and vomiting
• Muscle aches
• Confusion
• Loss of balance
• Convulsions

Doctors say a severe listeriosis infection can spread to your bloodstream or brain – leading to sepsis, meningitis, or even encephalitis.

"Listeria spreads easily among deli equipment, surfaces, hands, and food. Refrigeration does not kill listeria, but reheating to a high enough temperature before eating will kill any germs that may be on these meats," the Centers for Disease Control and Prevention said earlier this month in addressing the outbreak.

Doctors say listeria can be treated with the help of prescribed antibiotics that can help you get rid of the infection. Antibiotics commonly used to treat listeriosis include sulfamethoxazole and ampicillin. However, if you have mild symptoms, you may not need treatment.

If your baby is born with a listeriosis infection, your healthcare provider will give them antibiotics shortly after birth.