Infant dead in listeria outbreak tied to Yu Shang Food ready-to-eat meat and poultry products: CDC

An infant has died in a listeria outbreak linked to a brand of ready-to-eat meat and poultry products, federal authorities said Friday.

As of Friday, 11 people have been infected in four states in the outbreak, according to the U.S. Centers for Disease Control and Prevention. Among them, nine people have been hospitalized and an infant from California has died, the CDC said.

The infections have been linked to recalled ready-to-eat meat and poultry products by Yu Shang Food, based in Spartanburg, South Carolina, according to the CDC. The recalled products include pork hock, chicken feet, pork feet, duck neck, beef shank and pork tongue.

ABC News has reached out to Yu Shang Food for comment.

Most of the cases -- seven -- were in California, while two were in Illinois and one each in New York and New Jersey, according to the CDC. Those infected ranged in age from under 1 to 86, with a median age of 64, according to the CDC.

The infant who died and his pregnant mother were both infected in the outbreak, according to the CDC. The infant had a twin who also died, though listeria was not found in the other twin's sample and the case is not included in the outbreak, the CDC said.

One other listeria illness was reported in an infant who recovered, the CDC said.

"The true number of sick people in this outbreak is likely higher than the number reported, and the outbreak may not be limited to the states with known illnesses," the CDC said.

Yu Shang Food has recalled approximately 72,240 pounds of ready-to-eat meat and poultry products due to possible listeria contamination, the U.S. Department of Agriculture’s Food Safety and Inspection Service (FSIS) said on Thursday.

The recalled foods include products made before Oct. 28, the CDC said. The products subject to recall have the number “P-46684” or “EST. M46684” inside the USDA mark of inspection. They were shipped to retail locations nationwide and were sold online.

The full list of recalled items can be viewed here. Anyone with the products is advised to throw them away or return them to the place of purchase, and surfaces should be thoroughly cleaned. Listeria can survive in the refrigerator at cooler temperatures and easily contaminate other foods.

"FSIS is concerned that some product may be in consumers’ refrigerators/freezers," the agency said.

The FSIS said the problem was discovered when a finished food product produced by Yu Shang Food tested positive for listeria on Oct. 21. Listeria was detected in additional testing of product and environmental samples collected by the FSIS, it said.

"Working in conjunction with public health partners, FSIS determined that there is a link between the [ready-to-eat] meat and poultry products from Yu Shang Food, Inc. and an illness cluster," the FSIS said.

The company initially issued a recall on Nov. 9 that was expanded on Thursday.

People aged 65 and older, pregnant women and those with weakened immune systems are more at risk of serious illness due to listeria, according to the CDC.

Symptoms usually start within two weeks of eating food contaminated with listeria and can include fever, muscle aches, headache, tiredness, stiff neck, confusion, loss of balance and seizures, according to the CDC.

The CDC advises contacting a health care provider right away if symptoms develop.