A parasitic outbreak, causing symptoms like severe diarrhea, is spreading across the Midwest. Health officials indicate that it may take weeks to identify the source. As of July 13, over 3,000 cases of cyclosporiasis, an illness from the parasite Cyclospora cayetanensis, have been reported in Michigan and Ohio. Additional cases are linked to West Virginia and Kentucky. Nationally, the CDC reports more than 7,000 cases confirmed or under investigation across 34 states since May 1.
Potential Source of the Outbreak
Michigan health officials suspect lettuce or salad greens might be behind the outbreak, although other foods are not excluded. The CDC is gathering information to solve this mystery. Federal officials expect the outbreak to continue through August as they work to trace contamination through the food supply chain. Cyclospora is not the only parasite that can be present in fruits and vegetables.
Expert Opinions
Jason Reese, a food safety expert and co-founder of the Indiana-based law firm Wagner Reese LLP, discussed the challenge of tracing cyclospora’s spread. He explained, “The spread comes from contaminated fecal matter making its way to food or water and then into a person’s mouth. Unlike norovirus, this isn’t spread person to person. Contamination typically occurs at the farm or during processing. A simple error like tainted irrigated water, poor worker hygiene, or supply chain issues can cause it.”
He advised consumers to be cautious with produce like bagged salads, herbs, green onions, snow peas, leafy greens, and raspberries. Reese noted that contamination is usually invisible and may take a week to show symptoms, making it hard to trace back to a specific meal.
Other Parasites of Concern
Cyclospora
This parasite is often found in imported produce. Past outbreaks have linked it to basil, cilantro, snow peas, and berries. Studies also found it in lettuce, which is the suspected source of this outbreak. Washing can remove about 80% of the pathogen, but cooking is necessary to kill it. Cyclospora does not naturally occur in the U.S., with domestic outbreaks tracing back to imported foods.
Cryptosporidium
This is typically found in water and produce washed with contaminated water. While washing helps, it only works if the water is clean. Cooking effectively kills the parasite. Cryptosporidium can be dangerous for those with weakened immune systems, and prolonged diarrhea should warrant a doctor’s visit. The parasite is resistant to chlorine, requiring filtration to remove it from drinking water. It was involved in the largest U.S. waterborne disease outbreak in Milwaukee in 1993.
Giardia
Known as G. lamblia, this parasite spreads through water and contaminated produce. Although treatable and typically not dangerous, prolonged symptoms should be evaluated. Cooking kills giardia, which is often found in pets that can spread it to humans. Precautions are necessary when handling sick pets, and labs often test for giardia alongside cryptosporidium because of their similarities.
Toxoplasma gondii
Mainly associated with undercooked meat, particularly pork, and contaminated produce, this parasite requires cooking to the proper temperature for elimination. While most infections are mild, it can cause serious conditions affecting the eyes, lungs, and brain. Those exposed should receive treatment, particularly if immunocompromised or pregnant. Roberts advises pregnant women never to change cat litter, as cats can spread the parasite. Toxoplasma is a leading cause of death and hospitalization among foodborne pathogens in the U.S.