Story highlights Illinois is reporting 90 illnesses, Iowa is reporting 15

McDonald's is replacing salad mix in approximately 3,000 US restaurant locations

(CNN) The Illinois and Iowa health departments are investigating outbreaks of a parasite that causes intestinal illness and might be linked to McDonald's salads, both states said Thursday.

The cyclospora parasite causes intestinal illness as a result of consuming contaminated food or water. Symptoms can begin a week or more after consuming the parasite. They include diarrhea and frequent, sometimes explosive bowel movements, according to the US Centers for Disease Control and Prevention. Those who are infected might also experience loss of appetite, weight loss, stomach cramps or pain, nausea, gas and fatigue. Vomiting, headache, fever, body aches and flu-like symptoms can also occur.

The illness can last from a few days to a few months and patients might feel better, then get worse again. Patients can be treated with antibiotics.

According to the Illinois Department of Public Health, the illnesses have been reported across multiple counties in the state, although no counties were named.

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