The U.S. Department of Agriculture issued a health alert over pre-made salads and wraps sold at stores including Trader Joe's, Kroger and Walgreens, due to concerns they may be contaminated with cyclospora, an intestinal parasite.

The concern is over recalled romaine lettuce that may have been used in the wraps and salads, according to the USDA.

People are being warned to check their refrigerators for any of the beef, pork and poultry products affected by the alert.

Unlike E. coli and salmonella, which are bacteria, cyclospora is a parasite. It's what caused at least 286 people to become sick in an outbreak likely linked to McDonald's salads.

The parasite, which causes an intestinal illness, is usually transmitted by consuming food or water contaminated with feces, according to the Centers for Disease Control and Prevention.

The items listed in the health alert were produced between July 15 and July 18, and have a sell-by date ranging from July 18 to July 23. Customers can find a complete list of the products here, and labels of the products here.

The products come from Caito Foods, a distributor in Indianapolis, Indiana, which learned from its lettuce supplier, Fresh Express, that the romaine that is used to manufacture some of its salads and wraps was being recalled, according to the USDA.

The USDA issued the alert "out of an abundance of caution," but urged customers with the possibly affected products to throw them away or return them to the stores.