Giant Eagle, a chain of supermarkets based outside Pittsburgh, has reportedly recalled eight-ounce bags of shredded iceberg lettuce after being notified the farm that produced them had tested positive for the listeria bacteria.

According to California-based River Ranch Fresh Foods LLC, which is the farm in question, following the fact that certain samples have tested positive, they have recalled a further 2,154 salad cases. Earlier, the US Food and Drug Administration (FDA) representative had contacted both Giant Eagle and River Ranch, informing them about the presence of listeria found during routine testing of their iceberg lettuce samples.

According to the Wall Street Journal, River Ranch Fresh Foods said it distributed the recalled bags of salad in Ohio, Pennsylvania and Iowa. Apart from the iceberg lettuce, the recalled bags also contain Parisian blend, leafy romaine, romaine garden, American blend and garden supreme salads.

This recall comes amid ongoing concerns of the listeria outbreak, which was connected to tainted cantaloupes that has reportedly killed 23 people till date.

USA Today reported that the outbreak is now one of the deadliest in the U.S., having become more virulent than another listeria outbreak in 1985m when a Mexican-style soft cheese from Jalisco Products killed 18 adults and 10 newborns. Apart from this, the outbreak also caused around 20 miscarriages and seriously affected142 others, as per reports by the Center for Disease Control (CDC).

Listeriosis, caused by the bacteria Listeria, is a food-borne disorder and an important public health problem in countries like the U.S.

On Sep.14, 2011, the FDA announced that Jensen Farms' packing facility in Colorado issued a voluntary recall of its Rocky Ford-brand cantaloupes after being linked to a multistate outbreak of listeriosis.

Although Jensen Farms issued a voluntary recall of its products, affected cases were reported because of the time lag between diagnosis and laboratory confirmation. This was also because there can, potentially, be a gap of upto 2 months between eating the contaminated food and developing listeriosis.

The CDC has recommended that consumers not eat whole or pre-cut Rocky Ford-brand cantaloupe from Jensen Farms. This is especially important for older adults, persons with weakened immune systems and pregnant women.