Sun Tree LLC is voluntarily recalling walnuts comprising of 46 cases of 24 count 12oz produce bags, California Grown Shelled Walnuts, Lot No. 42720, Best by 12/11/2014 UPC code, 69887507806, because it has been determined that there is a possibility of contaminated with Listeria monocytogenes. Listeria monocytogenes is an organism which can cause serious and sometimes fatal infections in young children, frail or elderly people, and others with weakened immune systems. Although healthy individuals may suffer only short-term symptoms such as high fever, severe headache, stiffness, nausea, abdominal pain and diarrhea, Listeria infection can cause miscarriages and stillbirths among pregnant women.