Last Updated Jul 20, 2018 3:07 PM EDT
An outbreak of intestinal illness linked to eating salads from McDonald's is widening.
A week after health officials first alerted the public, the count of cases tied to the cyclospora parasite has increased to 163 people, three of them hospitalized, and now includes residents from 10 states.
Health officials are investigating cyclospora illnesses associated with McDonald's locations in nine states, including Illinois, Iowa, Kentucky, Minnesota, Missouri, Nebraska, Ohio, South Dakota and Wisconsin. A Florida resident also became ill after purchasing a salad while traveling in Kentucky.
The Food and Drug Administration is working with McDonald's to identify the ingredients that may have made people sick and to "trace back those ingredients through the supply chain."
Transmitted in foods tainted by fecal matter, cyclospora can cause stomach cramps, nausea and flu-like symptoms a week or more after someone consumes food or liquid contaminated with the parasite.
The outbreak,, prompted the fast-food chain to temporarily stop selling salads at the restaurants identified as possible sites of contamination. The company also said it was switching lettuce suppliers.
As of July 13, McDonald's had decided to stop selling salads at restaurants in 14 states, according to the FDA. They are Illinois, Indiana, Iowa, Michigan, Missouri, Minnesota, Nebraska, Ohio, North Dakota, South Dakota, Montana, Kentucky, West Virginia and Wisconsin.
"The additional states identified by the FDA and CDC (Centers for Disease Control and Prevention) are among the same states where a week ago we proactively decided to remove our lettuce blend in impacted restaurants and replace it through a different supplier," McDonald's said Friday in a statement.
Separately, the CDC says 78 people in four states -- Iowa, Michigan, Minnesota and Wisconsin -- have been sickened by cyclospora linked to now-recalled Del Monte Fresh Produce vegetable trays.