More than 100 people have become ill from a parasite possibly linked to McDonald's salads.
Health officials in Iowa and Illinois are investigating an outbreak of cyclosporiasis -- an intestinal illness.
Illinois says it has seen about 90 cases since May.
Iowa is reporting 15 cases since June.
McDonald's, the world's largest restaurant chain, says it is working with public health authorities in both states.
And has voluntarily stopped selling salads at the some 3,000 affected locations until it could switch to another lettuce blend supplier.
Cyclospora infections are spread by ingesting food or water contaminated with the parasite.
Several outbreaks have occurred in the U.S. in the past several years linked to contaminated produce.
Symptoms include watery diarrhea, loss of appetite, cramping, bloating, nausea and fatigue.
The outbreak comes on the heels of another major recall of the popular Kellogg's cereal Honey Smacks which has been linked to a salmonella outbreak that has infected 100 people in more than 30 states.