Tons of ready-to-eat and ready-to-cook foods have been recalled because of listeria contamination at a California onion plant.

Gills Onions of Oxnard, Calif., processes more than 90,000 tons of red and yellow onions per year. A wide variety of products use the plant's chopped, slivered, and peeled onions.

How many products? A flood of recalls followed Gills' July 25 announcement expanding an earlier recall to include all onions made at the plant. As of Aug. 2, there have been at least 15 separate recalls, involving major brands such as Trader Joe's, Wegmans, Whole Foods, and Publix.

Foods containing the onions have ranged from fresh salsa to chicken salad to bean dip. All of the recalls, including a description of all the products, their sell-by dates, and product codes, are available on an FDA web site.

Although the Gills onions were sold only in 12 U.S. states and in Canada, products containing the onions were shipped to additional states. For example, yesterday's recall of Garden-Fresh salsa, salads, slaw, bean, and dip products containing Gills onions went out to 14 states. Nine of those states were not included in the Gills recall.

The recalls began on July 18, a day after a random test of a bag of Gills yellow onions at a retail outlet showed contamination with listeria bacteria. Gills immediately shut down its plant on July 17, as soon as it learned of the FDA tests. After finding listeria at the facility, the company voluntarily expanded its recall. The plant remains closed.

No illnesses have yet been linked to the recalled products. Many, but not all of the recalled products have reached their sell-by dates. Gills says its products have a 16-day shelf life.
Symptoms of Listeria Food Poisoning

Serious cases of listeria infection -- listeriosis -- are relatively rare. People at high risk are elderly people and people with weakened immune systems. Pregnant women usually do not get serious illness themselves, but the infection can cause miscarriage, stillbirth, premature delivery, or fatal infection of the newborn.

People with listeria food poisoning usually come down with a case of diarrhea, often with a fever. Over days or weeks, more serious symptoms may develop: fever, stiff neck, confusion, muscle weakness, and/or vomiting.

Although symptoms may appear as soon as three days after eating contaminated food, symptoms usually appear in one to three weeks. However, some people become ill two months after eating contaminated food.