(Bloomberg) -- Blue Bell CreameriesInc., working to contain the spread of listeria after threepeople died from the bacterial disease, expanded a product recallto include everything it makes.

Following an earlier recall of some ice cream, listeria has beenfound in several different places and plants, the Brenham,Texas-based company said. The affected products -- including icecream, frozen yogurt and other snacks -- were distributed to retailoutlets in 23 U.S. states, including California, Texas, Florida andIllinois, as well as international locations. The recall includes 8million gallons of ice cream and other products, the companysaid.

“At this point, we cannot say with certainty how listeria wasintroduced to our facilities and so we have taken thisunprecedented step,” Chief Executive Officer Paul Kruse said in astatement on the family-owned company’s website. “We areheartbroken about this situation.”

The decision was made after the company’s sampling programshowed that chocolate chip cookie dough ice cream manufacturedMarch 17 and March 27 contained the bacteria. Blue Bell has nowreceived several positive tests for listeria in different placesand plants.

Three people died after eating tainted Blue Bell ice cream at aKansas hospital, and seven others from Kansas, Arizona, Oklahomaand Texas have been infected, according to the Centers for DiseaseControl and Prevention. The CDC and the Food and DrugAdministration are investigating the outbreak.

Food contamination

Listeria is a serious infection, usually caused by eating foodcontaminated with the listeria monocytogenes bacterium. Thebacteria is found in soil and water and can be carried by someanimals and transferred to meat and dairy products, according tothe U.S. Department of Health and Human Services.

Unlike many other bacteria, listeria can grow in coldtemperatures and can only be killed by cooking or pasteurizing.Some of the most at-risk foods include deli meats, raw milk andother dairy products, soft cheese, and sprouts. The diseaseprimarily affects older people, pregnant women, newborns or adultswith weakened immune systems, according to the CDC.

Symptoms include fever and muscle aches, sometimes preceded bydiarrhea or other gastrointestinal symptoms. Infection can lead tomiscarriage or stillbirth in pregnant women, the CDC said.

Blue Bell isn’t the only company recalling products overlisteria fears. Sabra Dipping Co. said this month it would callback 30,000 cases of hummus after a sample tested positive for thebacteria in Michigan. In that case, there were no immediate reportsof illness.

Blue Bell’s Kruse said his company is now sanitizing equipmentand expanding the number of times it swabs and tests its plants by800 percent.

“We continue to work with our team of experts to eliminate thisproblem,” he said.

--With assistance from Anna Edney in Washington.

Copyright 2018 Bloomberg. All rightsreserved. This material may not be published, broadcast, rewritten,or redistributed.