Consumers in the United States have been advised not to eat prepackaged caramel apples, after they were linked to five deaths and more than two dozen people falling ill in 10 states.

The U.S. Centers for Disease Control and Prevention (CDC) said that it was collaborating with state health officials and with the U.S. Food and Drug Administration (FDA) to investigate an outbreak of Listeria monocytogenes infections (listeriosis) that has been connected to commercially produced, prepackaged caramel apples.

The first illness linked to the outbreak was reported on October 17 and the last one on November 27. However, there may yet be more cases because the products can have a shelf life of over a month and illnesses that have occurred since early December may not have been reported yet.

As of December 22, a total of 29 people infected with the outbreak strains of Listeria monocytogenes have been reported in Arizona (4), California (1), Minnesota (4), Missouri (5), New Mexico (5), North Carolina (1), Texas (4), Utah (1), Washington (1) and Wisconsin (3).

All 29 ill people were hospitalized, and five deaths have been reported. According to CDC, listeriosis contributed to three of these deaths and it is unclear whether it contributed to a fourth. The fifth death was unrelated to listeriosis.

As a precaution, CDC recommends that U.S. consumers do not eat any commercially produced, prepackaged caramel apples, including plain caramel apples as well as those with nuts, sprinkles, chocolate or other toppings, until more specific guidance can be provided.

The agency said that investigators are working to determine specific brands or types of caramel apples that may be linked to the outbreak and to identify the source of contamination.

No illnesses related to this outbreak have been linked to apples that are not caramel-coated and not prepackaged or to caramel candy.