Blue Bell Ice Cream has suspended operations at its Oklahoma plant after health officials linked the deaths of three people to contaminated ice cream.

“We are taking this step out of an abundance of caution to ensure that we are doing everything possible to provide our consumers with safe products and to preserve the trust we have built with them and their families for more than a century,” the company said in a statement on April 3.

Last month, Blue Bell and health officials said a 3-ounce cup of ice cream contaminated with listeriosis was traced to a plant in Broken Arrow, Oklahoma. The now-recalled ice cream product — cups of chocolate, strawberry and vanilla — is not sold in retail locations and is shipped in bulk to “institutional accounts” such as hospitals in 23 states that comprise less than 5% of the company’s sales.

“We recommend that consumers do not eat any Blue Bell brand products made at the company’s Oklahoma facility and that retailers and institutions do not sell or serve them,” the U.S. Centers for Disease Control and Prevention (CDC) said on April 3.

Ten products recalled earlier in March were from a production line at a plant in Brenham, Texas, the company’s headquarters.

The recall, the first in Blue Bell’s 108-year history, began when five patients at Via Christi St. Francis hospital in Wichita, Kansas, became ill with listeriosis while hospitalized at some point from December 2013 to January 2015. Officials determined at least four drank milkshakes that contained Blue Bell ice cream. Three of the patients later died.

Listeriosis is a life-threatening infection caused by eating food contaminated with bacteria called Listeria monocytogenes, according to the CDC. The disease primarily affects pregnant women, newborns, older adults and people with weakened immune systems.

The CDC also said on April 3 that it has identified six patients with listeriosis between 2010 and 2014 that was indistinguishable from that found in the 3-ounce cup ice cream product traced to the Oklahoma plant.

Four of the six patients were hospitalized in Texas for unrelated problems before developing listeriosis, according to the CDC.

The one patient for whom information is available reported eating ice cream in a Texas hospital before developing listeriosis and the Texas Department of State Health Services reported the hospital had received Blue Bell brand ice cream cups, the CDC said.

The “investigation to determine whether these illnesses are related to exposure to Blue Bell products is ongoing,” the CDC said.

Blue Bell said it will conduct a “careful and complete examination” of its Oklahoma plant “to determine the exact cause of the contamination.”

“Once our investigation is complete and we have made all necessary improvements, it will return to operation,” according to Blue Bell’s statement.

“Our other plants continue to operate and supply our products to retail stores and institutional customers.”

The FDA has been notified of Blue Bell’s decision to voluntarily shut down the plant, the company said.

In addition to the Broken Arrow plant, Blue Bell has two plants in Brenham and one in Sylacauga, Alabama.

The recalled ice cream had been shipped to Alabama, Arizona, Arkansas, Colorado, Florida, Georgia, Illinois, Indiana, Kansas, Kentucky, Louisiana, Mississippi, Missouri, Nevada, New Mexico, North Carolina, Ohio, Oklahoma, South Carolina, Tennessee, Texas, Virginia and Wyoming.

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