From the Centers for Disease Control website:

CDC is collaborating with public health officials in several states and with the U.S. Food and Drug Administration (FDA) to investigate an outbreak of Listeria monocytogenes infections (listeriosis) linked to commercially produced, prepackaged caramel apples.Listeria can cause a serious, life-threatening illness. People at higher risk for listeriosis include adults 65 years or older, people with weakened immune systems, and pregnant women. In interviews, ill people answered questions about foods consumed and other exposures in the month before becoming ill. To date, 25 (89%) of the 28 ill people interviewed reported eating commercially produced, prepackaged caramel apples before becoming ill. The three ill people interviewed who did not report eating caramel apples did report eating whole or sliced green apples not covered in caramel. The source of these apples is unknown, and it is unknown whether these apples are linked to the patients’ illnesses.

Since the last case count update, one additional death was reported. It is unclear whether Listeria infection contributed to this death.

On Jan. 6, Bidart Bros. of Bakersfield, California voluntarily recalled Granny Smith and Gala apples because environmental testing revealed contamination with Listeria monocytogenes at the firm’s apple-packing facility. The recall includes all Granny Smith and Gala apples shipped from its Shafter, Calif. packing facility in 2014.

On Jan. 8, FDA laboratory analyses showed that environmental Listeria isolates from the Bidart Bros. facility were indistinguishable from outbreak strains by pulsed-field gel electrophoresis (PFGE). Listeria isolates from whole apples produced by Bidart Bros., collected along the distribution chain, were also indistinguishable from outbreak strains by PFGE.

CDC recommends that consumers not eat any of the recalled Granny Smith and Gala apples produced by Bidart Bros. and that retailers not sell or serve them.

To date, three firms that produce caramel apples have issued voluntary recalls after receiving notice from Bidart Bros. that there may be a connection between Bidart Bros. apples and this listeriosis outbreak. On Dec. 24, 2014, Happy Apple Company of Washington, Mo., voluntarily recalled Happy Apples brand caramel apples with a best use by date between Aug. 25 and Nov. 23, 2014.

On Dec. 31, 2014, Happy Apple Company expanded the recall to include Kroger brand caramel apples produced by Happy Apple Company with a best use by date between Sept. 15 and Nov. 18, 2014.

On Dec. 27, 2014, California Snack Foods voluntarily recalled Karm’l Dapple brand caramel apples with a best use by date between Aug. 15 and Nov. 28, 2014.

On Dec. 29, 2014, Merb’s Candies of St. Louis, Missouri issued a voluntary recall of Merb’s Candies Bionic Apples and Double Dipped Apples that would have been available from Sept. 8 through Nov. 25, 2014.

Investigators are continuing to work to determine if any other brands or types of commercially produced, prepackaged caramel apples are linked to illnesses and to determine the source of contamination.

CDC, the involved states, and FDA continue to work closely on this rapidly evolving investigation, and new information will be provided as it becomes available.