On December 19, 2014 the CDC announced a multistate outbreak of Listeria monocytogenes infections linked to commercially produced, prepackaged caramel apples. On February 12, 2015 the outbreak was declared to be over. A total of 35 people infected with the outbreak strains of Listeria monocytogenes were reported from 12 states. Of these, 34 were hospitalized. Listeriosis contributed to at least 3 of the 7 deaths reported. Eleven illnesses were pregnancy-related with one illness resulting in a fetal loss. here invasive illnesses were among otherwise healthy children aged 5-15 years. Twenty-eight (90%) of the 31 ill persons interviewed reported eating commercially produced, prepackaged caramel apples before becoming ill. Illness onset dates ranged from October 17, 2014 to January 6, 2015. The Public Health Agency of Canada identified one case of listeriosis that was genetically related to the US outbreak. The investigation was assigned Cluster ID #1411MNGX6-1.

On December 24, 2014 Happy Apples issued a voluntary recall of Happy Apple brand caramel apples with best use by date between August 25th and November 23rd, 2014 due to a connection between the apples and outbreak associated cases. California Snack Foods brand caramel apples issued a similar recall on December 27th. Both companies used apples supplied by Bidart Brothers. On December 29 Merb's Candies recalled Bionic Apples and Double Dipped Apples. On January 6, 2105 Bidart Bros. of Bakersfield, California recalled Granny Smith and Gala apples because environmental testing revealed contamination with Listeria monocytogenes at the firm's apple-packing facility. On January 8, 2015 FDA laboratory analyses using PFGE showed that environmental Listeria isolates from the Bidart Bros. facility were indistinguishable from the outbreak strains. On January 18, 2015 whole genome sequencing (WGS) found these isolates were highly related to the outbreak strains. In addition WGS showed that Listeria isolated from whole apples produced by Bidart Bros., collected along the distribution chain, also were highly related to the outbreak strains.