An infant in California died in a listeria outbreak that has now prompted a recall of ready-to-eat meat, the Centers for Disease Control and Prevention (CDC) said.

The child’s pregnant mother also fell ill with listeria. The child’s twin died as well, but testing could not find listeria in that infant.

The CDC said eleven people had been reported as infected in four states between October 2021 and July 2024. It was not clear when the baby died.

The outbreak led to a recall this month of ready-to-eat meat products manufactured by Yu Shang Food Inc.

Seven ill people were reported in California, two in Illinois and one each in New York and New Jersey.

The CDC said the true number of sick people is “likely much higher” and the outbreak may not be limited to those states.

Some people recover without medical care and are not tested, while more recent illnesses may not yet be reported as it usually takes three to four weeks to determine if a sick person is part of an outbreak, the health agency said.

Listeria are bacteria that can contaminate food and lead to listeriosis, a serious infection that primarily affects older adults, people with weakened immune systems, pregnant women and newborns.

Listeriosis can cause fever, muscle aches, headache, stiff neck, confusion, loss of balance and convulsions, and sometimes diarrhoea and gastrointestinal symptoms.

Listeria infection is the third leading cause of death from foodborne illness in the US, the CDC said. The agency estimates that each year, 1,600 people are infected with listeria and 200 die from the infection.