(CNN)  -- A recall has been issued for enoki mushrooms produced by Phillips Mushroom Farms in Pennsylvania.



The recall covers 3.5-ounce packages of enoki mushrooms bearing UPC 33383 67540.



The mushrooms were packed in clear plastic bags with blue or green graphics and sold from January 13 to 30. Enokis are long, thin white mushrooms, often used in Asian cuisines.



Preliminary test results showed potential listeria contamination, but no illnesses have been reported, according to Phillips Mushroom Farms.



Listeria can cause flu-like symptoms, including fever and muscle aches, and sometimes gastrointestinal symptoms such as nausea or diarrhea, according to the Centers for Disease Control and Prevention.



It affects primarily the elderly, pregnant women, newborns and people with weakened immune systems.



Retailers are asked to remove the mushrooms from their shelves, pending further instructions.



Consumers are asked to return the mushrooms to the place of purchase for a full refund.



Visit http://www.phillipsmushroomfarms.com/ or call 800-722-8818 for more information.
When did it occur
January 13 to 30.
question: When did it occur, answer: January 13 to 30.