Twelve people were hospitalized and one person has died since July as a result of a listeria outbreak linked to Dole packaged salads, the U.S. Centers for Disease Control and Prevention (CDC) said Friday. Cases were reported in Indiana, Massachusetts, Michigan, New Jersey, New York and Pennsylvania.

Tests from the Ohio Department of Agriculture revealed listeria bacteria was found in a package of Dole field greens produced at a processing facility in Springfield, Ohio. Dole has since shut down the facility and is removing all salads made there that are still on the market, a news release said.

The CDC recommended consumers not eat packaged salads produced at the Dole processing facility in Springfield, including Dole, Fresh Selections, Simple Truth, Marketside, Little Salad Bar and President’s Choice brands. The packaged salads can be identified by the letter “A” at the beginning of the manufacturing code found on the package, the CDC said in a news release.

Listeria is a hardy bacterium resistant to extreme hot and cold temperatures. Symptoms of listeria include fever, stiff neck, confusion, weakness and vomiting that can last days to weeks. People particularly at risk are pregnant women, older adults and those with weakened immune systems.

Roughly 800 cases of listeria are diagnosed each year in the United States along with three or four outbreaks, CNN reported.

From 1998 to June 2009, 48 deaths attributed to listeria illnesses were reported by the CDC.  Last year, Sabra Dipping Co. recalled 30,000 cases of hummus due to a possible listeria contamination, and Amy’s Kitchen Co. recalled nearly 74,000 cases of its products due to the foodborne illness.