NEW YORK — Nearly 1,000 individuals in Michigan have contracted a parasitic infection that can cause prolonged episodes of watery diarrhea, marking the largest outbreak of its kind in the state’s history and one of the most significant in the U.S. in recent years.
While no fatalities have occurred, the source of the cyclospora infections remains unidentified. Similar illnesses are under investigation in 28 other states, including Ohio, where individuals near the Michigan border are also affected.
The outbreak was first announced by Michigan officials last week, noting more than 170 cases primarily in the southeastern region of the state since June 22. Typically, Michigan reports about 50 cases annually.
By Wednesday, the state’s reported cases had increased to 992, with approximately 40 hospitalizations. In Lucas County, Ohio, 306 cases were recorded as of Wednesday, contributing to over 500 cases in northwest Ohio.
Tracking cyclospora outbreaks can be challenging, and pinpointing the source of foodborne illnesses can be difficult. However, Dr. Natasha Bagdasarian, Michigan’s chief medical executive, stated to The Associated Press that “there is clearly a linked outbreak happening right now.”
Here’s an overview of the current situation:
What is cyclospora?
Cyclospora is a microscopic, spherical parasite that often leads to watery diarrhea “with frequent and sometimes explosive bowel movements,” as described by the U.S. Centers for Disease Control and Prevention. The illness, known as cyclosporiasis, is usually not life-threatening and is generally treated with antibiotics. Outbreaks tend to be more common in late spring and summer.
This parasite thrives in warm conditions and spreads through feces. Historically, infections have occurred from consuming fruits or vegetables that were irrigated with contaminated water.
Although cyclospora is less common than other foodborne illnesses like salmonella and E. coli, its incidence in the U.S. began to rise about a decade ago, notably spiking in 2018 and 2019. Experts link this increase to factors such as climate change and improved detection methods.
How does this outbreak compare to previous ones in the US?
While comprehensive data on cyclospora outbreaks are limited, a few documented incidents in the past 20 years have exceeded 1,000 cases. Notable examples include a 1997 outbreak linked to Guatemalan raspberries that affected over 1,000 people in the U.S. and Canada, and a 2019 outbreak connected to Mexican basil that sickened more than 2,400 individuals.
Understanding the true impact is difficult, according to Melanie Firestone, a foodborne illness researcher at the University of Minnesota. Tests for food poisoning are often not designed to detect cyclospora, leading to significant underreporting, she explained.
Additional challenges include the inability to culture the parasite in laboratories, hindering efforts to link it directly to contaminated produce. Identifying common food sources among those affected can be difficult, especially if a single ingredient like basil or cilantro is involved in various recipes.
Moreover, contaminated foods might be distributed to both grocery stores and restaurants, complicating the traceability of their origins. These investigations can extend for months and often conclude without identifying a definitive source.
What’s the current situation?
Cases continue to rise in southeastern Michigan, though it is not deemed a national health crisis.
Dianna Blau, the CDC’s acting head of the parasitic diseases branch, confirmed there is no evidence suggesting the parasite has become more infectious.
Although thousands of cyclospora cases are reported annually in the U.S., it remains unclear how this year will compare. Currently, case numbers are fourfold higher than at the same time last year, based on CDC national data, which significantly lags behind state reports.
Michigan appears to be most affected, but the state’s proactive approach in case investigation and reporting might contribute to the perception of a localized issue, according to Bagdasarian.
How can you protect yourself from cyclospora?
Individuals experiencing diarrhea persisting for a few days should consult a healthcare provider to discuss possible cyclospora infection, officials recommend.
To prevent infection, avoid consuming potentially contaminated food or water.
Thoroughly wash fresh produce before consumption. However, be aware that cyclospora can adhere strongly to certain foods, so washing may not completely eradicate the risk.
As investigations continue, Michigan officials advise purchasing whole heads of lettuce instead of prewashed, bagged varieties, and removing the outer two to three leaves before washing the remainder under running water.
Cooking vegetables when possible is also recommended.
— Mike Stobbe
