A California-based meat company has issued a voluntary recall of more than 21,000 pounds of frozen pizza product that may have been contaminated with Listeria monocytogenes.

The recall, announced by the U.S. Department of Agriculture's Food Safety and Inspection Service, was made after a routine sampling by RBR Meat Company, Inc. showed that their frozen pizzas were adulterated with Listeria.

The products affected by the recall is a 16-inch pizza labeled as "Marketside Extra Large Supreme Pizza" that was shrink wrapped and contained in a 50.6-oz. corrugated box. The frozen pizza has the lot code 20547 and bear establishment number "EST. 1821" inside the USDA mark of inspection. USDA noted that the potentially contaminated pizzas were shipped to retail distribution centers in California, Nevada, Utah and Washington.

According to the report from Business Insider, the frozen pizzas that could have listeria were also sold in Wal-Mart stores in 11 different states, including Colorado, Idaho, Montana, Wyoming, Oregon, Hawaii and Alaska.

The USDA-FSIS urged consumers who bought the frozen pizzas not to consume it. The recalled products should be thrown away or returned to the place of purchase. So far, there have been no confirmed reports of adverse reaction due to the consumption of the contaminated product.

Foods contaminated with L. monocytogenes can cause serious infection called Listeriosis, which primarily affects older persons and people with weakened immune system. The infection also has negative implications to pregnant women and their newborns.

Common symptoms of Listeriosis include fever, muscle aches, headache, stiff neck, confusion, loss of balance and convulsions sometimes preceded by diarrhea or other gastrointestinal symptoms. A more invasive form of the infection could spread beyond the gastrointestinal tract.

Pregnant women who acquired Listeriosis were at risk of miscarriages, stillbirths, premature delivery or life-threatening infection of the newborn. The elderly and people with weakened immune system can also acquire serious and fatal infection from eating contaminated foods, such as the frozen pizza.

Listeriosis can be treated with antibiotics. However, people who are at a higher risk of the infection and have been experiencing flu-like symptoms within two months after eating the contaminated food are encouraged to quickly seek medical help and tell the health care provider about eating the adulterated food.