Photo: Scott Olson (Getty Images)

Even under the best of circumstances, ordering salad at McDonald’s is a dicey endeavor. But now an outbreak of the foodborne parasite cyclospora has sickened over 100 people in Iowa and Illinois since May, and several cases are tied to salads purchased at the fast food giant.

The outbreaks were jointly reported Thursday by Iowa and Illinois health officials. In Illinois, about 90 cases have been seen since mid-May, with a quarter of victims reporting that they had eaten McDonald’s salads soon before they became sick. In Iowa, at least 15 people are thought to have eaten these salads just before developing a cyclospora infection, or cyclosporiasis, from late June to early July.

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“Anyone who ate these salads since the middle of June and who developed diarrhea, especially watery diarrhea and fatigue, should see their health care provider and get tested for Cyclospora to ensure an accurate diagnosis and appropriate treatment,” Patricia Quinlisk of the Iowa Department of Public Health said in a statement.

The bug, formally known as Cyclospora cayetanensis, is a single-celled protozoan that makes its home exclusively in humans. Initially identified in the 1970s, it took until the 1990s before doctors realized that cyclospora could be a major source of foodborne illness. The infection typically causes diarrhea, loss of appetite, bloating and gas, and sometimes mild fever, and can be treated with antibiotics. Not everyone who gets infected becomes sick, though.

Unlike some incredibly contagious stomach bugs such as norovirus, there’s less worry about spreading cyclospora to your close loved ones or friends. The bug spreads through oocysts (an early stage of life in some parasites) that are passed out in a person’s feces. But these oocysts need about a week or two in the outside environment to mature before they can become infectious. Though cyclospora is endemic in some countries’ water supply (where it’s a common cause of traveler’s diarrhea), in the US, it’s typically only spread through imported contaminated produce.

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This latest outbreak isn’t the only splash cyclospora has made this year stateside. A seemingly separate outbreak of the parasite was traced to Del Monte Fresh Produce vegetable trays in mid-June, prompting recalls. According to the Centers for Disease Control and Prevention, the latter outbreak has sickened at least 227 people since early May.

In a statement released Friday, McDonald’s said it will stop selling salad items at all of the restaurants to which cases have been traced, until a new lettuce blend supplier can be found. It is also in the middle of removing “existing lettuce blend from identified restaurants and distribution centers.” The move is expected to affect 3,000 locations in 14 states. Aside from Iowa and Illinois, the other states are Indiana, Ohio, North Dakota, South Dakota, Michigan, Minnesota, Montana, Nebraska, Wisconsin, Wyoming, Kentucky, and West Virginia.

[Iowa Department of Public Health, Illinois Department of Public Health]

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