At least 32 people in the United States have been sickened by listeria-tainted caramel apples — including six who have died — even as companies nationwide continue to recall the treats sold this fall, health officials said Wednesday.

Officials with the Centers for Disease Control and Prevention updated their figures in the growing outbreak, reporting that 31 of 32 victims have been hospitalized in 11 states. In addition, two cases related to the outbreak have been reported by the Public Health Agency of Canada.

Of the six deaths tied to the outbreak, all of the victims were confirmed to be infected with the outbreak strain of bacteria, but listeria contributed directly to only three of the deaths. It’s unclear whether listeria contributed to two others, and one death wasn’t related to the infection, health officials said.

The CDC continues to warn consumers not to eat any prepackaged caramel apples while the investigation into the listeria outbreak continues. That includes plain caramel apples and those decorated with nuts, sprinkles or chocolate.

Three companies have issued voluntary recalls for commercially produced, prepackaged caramel apples in connection with the outbreak that led to illnesses reported from Oct. 17 to Dec. 11.

Happy Apples of Washington, Mo., issued a recall on Dec. 24 for packaged apples sold at grocery stores, discount stores and club stores in more than 30 states. California Snack Foods of South El Monte, Calif., issued a recall Dec. 27 for all styles of its Karm’l Dapples products sold in Arizona, California, Nevada, Texas and Utah. And Merb’s Candies of St. Louis issued a recall of its Bionic Apples and Double Dipped Apples sold in St. Louis stores and by mail order nationwide.

All the retailers said they were issuing recalls after learning that Bidart Bros., a Bakersfield, Calif., apple producer, had voluntarily recalled fresh apples because they may be contaminated with listeria. In a letter to suppliers dated Dec. 22, company President Leonard Bidart said the firm had consulted with the federal Food and Drug Administration and California public health officials.

"Out of an abundance of caution tempered by our deep concern for public safety, we are instituting a recall of the processor apples we shipped to you during the 2014 season," the letter said.

FDA officials said Wednesday that the agency has traced the distribution of caramel apples eaten by eight outbreak victims to Bidart Bros. Although Happy Apples and Merb’s Candies receive apples from other growers, the investigation confirmed that Bidart is the onlyapple grower that supplied both companies.

The recalled apples are the Granny Smith variety, the FDA reported.

Caramel apples are typically a fall treat, and the products should not remain on retail store shelves, health officials said.

The outbreak includes victims in Arizona, 4; California, 2; Minnesota, 4; Missouri, 5; Nevada, 1; New Mexico, 6; North Carolina, 1; Texas, 4; Utah, 1; Washington, 1; and Wisconsin, 3.

Listeria bacteria can cause life-threatening infections in young children, pregnant women, the elderly and those with compromised immune systems. Symptoms can show up weeks or even months after exposure.