COLUMBUS, Ohio (AP/CBS) — Jeni’s Splendid Ice Creams has found listeria in its plant again and has halted production and closed retail shops for the second time since April, the company said Friday.

Listeria was discovered during routine swabbing that is part of the monitoring process, and the Columbus-based company is taking steps to figure out how it got into the plant, CEO John Lowe said in a statement on the company’s website.

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“We have a theory and are testing that theory,” he said.

He said safety protocols worked as intended, and no ice cream was contaminated.

There is no timetable for resuming production, Lowe said. Jeni’s is temporarily closing its 21 retail shops because there isn’t enough ice cream to keep them stocked.

For Chicago, that means two Jeni’s retail outlets on the North Side have been closed. Former Chicago customer Jeff Liberman says he won’t go back. But Shannon Heston says she’ll continue buying the ice cream.

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“I’m not super concerned. Everything I’ve heard about Listeria is that it affects people with compromised immune systems. I’m glad they’re being cautious but, I’m not concerned for myself so much,” she says.

It’s still possible to find Jeni’s ice cream on Chicago store shelves at Whole Foods, CBS 2’s Roseanne Tellez reports.

In the earlier listeria scare, Jeni’s shut down production April 23, recalled its products and closed shops after the bacteria was discovered in pints of ice cream and the plant. The company had traced the source to a pint-filling machine in the plant.

Jeni’s destroyed $2.5 million worth of ice cream, then cleaned and reworked production to try to prevent future contamination. Production resumed May 13, and shops reopened May 22.

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