Aug. 11 (UPI) -- Forty-one people have been sickened from McDonald's salads contaminated with a parasite a week after the last update, raising the total number of illnesses to more than 400.
Laboratory analysis confirmed 436 cases of the parasite infection called Cyclospora reported in people who consumed salads at McDonald's in 15 states, as of Thursday. This is 41 more cases than last week's update in the same number of states.
The cases mostly stem from restaurant locations in the Midwest with 219 cases in Illinois alone. The national Centers for Disease Control noted that Connecticut, Tennessee, and Virginia patients purchased salads while traveling in Illinois. The Florida patient purchased a salad in Kentucky.
The parasite can cause symptoms that include diarrhea, stomach cramps, bloating, nausea, fatigue and flu-like symptoms. If untreated, infected individuals may need more than a month to recover.
At least 20 people have been hospitalized and no deaths have been reported, according to the CDC.
"Epidemiologic evidence indicates that salads purchased from McDonald's restaurants are one likely source of these infections," the CDC said. "The investigation is ongoing, and FDA is working to determine the sources of the ingredients that were in common to the salads served at McDonald's."
Illnesses are usually reported within six weeks, so illnesses that started after June 21 may not be reported yet, the CDC said.
"At this time, there is no evidence to suggest that this cluster of illnesses is related to the Cyclospora outbreak linked to Del Monte fresh produce vegetable trays," the CDC's update last week said.
The Food and Drug Administration investigation into the outbreak continues.
"McDonald's is committed to the highest standards of food safety and quality control, a company statement on the salads said when more than 100 cases were reported in Illinois and Iowa last month. "We are closely monitoring this situation and cooperating with state and federal public health authorities as they further investigate."
In July, McDonald's also removed existing lettuce blend from identified restaurants and distribution centers - which includes approximately 3,000 of its U.S. restaurants primarily located in the Midwest.
Last month, the FDA completed analysis of an unused package of romaine lettuce and carrot mix distributed to McDonald's by the Fresh Express processor in Streamwood, Ill., which confirmed the presence of the microscopic parasite Cyclospora in that mix.
The U.S. Department of Agriculture's Food Safety and Inspection Service issued an alert on July 30 over concern certain beef, pork and poultry salad and wrap products that may also be contaminated with Cyclospora. The alert applied to certain salad and wrap products sold at Kroger, Trader Joe's and Walgreens locations nationwide and distributed by Caito Foods and Gordon Food Service.