An apple supplier headquartered in Bakersfield has been identified as a source of a contaminant called listeria, which has sickened 32 people across 11 states, including California. The Food and Drug Administration reported Wednesday that six people died after being infected with the bacteria.

A smokehouse in Santa Barbara is being investigated for possible contamination.

Listeriosis is a serious illness caused by eating food containing the bacteria Listeria monocytogenes. Symptoms include fever and muscle aches, gastrointestinal problems and chills. Pregnant women, older adults and newborns are at a high risk of infection.

The Centers for Disease Control and Prevention report that of 26 ill people interviewed, 23 reported eating commercially produced, pre-packaged, whole caramel apples. The FDA is currently investigating Bidart Bros., a Bakersfield apple supplier whose produce is used by Happy Apple Company and Merb’s Candies – two Missouri caramel apple companies that have issued voluntary product recalls because of potential contamination. A third caramel apple supplier, California Snack Foods in El Monte, has also issued a voluntary recall.

The California Department of Public Health joined the FDA in conducting an inspection of Bidart Bros. on Dec. 23. Surface swabs and environmental samples from the facility were tested and found to contain listeria. On January 6, the company voluntarily recalled all Granny Smith and Gala apples shipped from its Shafter location.

The FDA recommends that consumers avoid eating the recalled apples produced by Bidart Bros., which are also sold under the brand names “Big B” and “Granny’s Best,” under other brand names or under no brand. Consumers should not eat any pre-packaged caramel apples until more information is provided.

The California Department of Public Health also issued a warning Friday to consumers not to eat some Santa Barbara Smokehouse cold-smoked salmon products due to concerns about listeria contamination. The smokehouse in Santa Barbara is currently being investigated.