The Centers for Disease Control and Prevention warned consumers on Friday not to eat any romaine lettuce from Salinas, Calif., after at least 40 cases of E. coli infection nationwide were linked to contaminated products from that region.

In a statement detailing the E. coli outbreak, which has affected 16 states and left at least 28 people hospitalized, the C.D.C. also advised retailers not to sell any lettuce harvested in Salinas.

No deaths have been reported, but at least five people developed a type of kidney failure called hemolytic uremic syndrome, the agency said.

The strain behind the outbreak, E. coli O157:H7, produces a Shiga toxin that can cause painful cramps, bloody diarrhea and vomiting. Roughly 5 to 10 percent of the people who fall sick from that type of E. coli develop hemolytic uremic syndrome, a potentially life-threatening complication that occurs most commonly in young children under 5 years, older adults, and people with weakened immune systems, according to the agency.