In recent days, the number of cyclosporiasis cases—a parasitic infection known for causing severe, watery diarrhea—has skyrocketed in the United States, particularly with an unusually large outbreak of nearly 1,000 cases reported in Michigan.
Typically, Michigan sees around 50 cases annually, which makes this current situation the largest outbreak in the state’s history. Moreover, Ohio has experienced a significant uptick, reporting 177 cases as of July 2, following the latest count from the CDC.
As of June 16, the Centers for Disease Control and Prevention noted 145 cases across 17 states. Notably, this figure likely reflects a considerable underreporting, as state data shows much higher numbers and includes some hospitalizations.
While cyclosporiasis is rarely deadly, with no deaths attributed to this outbreak so far, the source of the infections remains unidentified, and the illness can have serious consequences. Here’s a closer look at what you should be aware of.
What is cyclosporiasis?
This gastrointestinal illness arises from the cyclospora parasite, which spreads through contaminated raw produce and water exposed to human waste.
In the U.S., cyclosporiasis tends to appear mostly in the warmer months—from May to August. Previous outbreaks have been linked to contaminated fresh fruits, vegetables, and herbs, including cilantro, basil, berries, and spinach.
The primary symptom is watery diarrhea characterized by frequent, sometimes urgent bowel movements. Interestingly, the diarrhea might improve and then come back.
Other symptoms can include cramps, nausea, fatigue, a decreased appetite, low-grade fever, and vomiting. These symptoms may last anywhere from a few days to over a month, and some individuals might not show any signs at all.
The time between ingesting the parasite and experiencing symptoms is usually about a week, but it can vary from two days to two weeks. It’s worth noting that cyclosporiasis isn’t typically spread from person to person.
While it’s not considered life-threatening, most people recover without treatment, though those with weakened immune systems may face higher risks. Antibiotics are generally used for treatment.
How does this compare to previous US outbreaks?
Historically, U.S. cases have often resulted from consuming fruits or vegetables that came in contact with feces-tainted irrigation water.
For instance, a significant outbreak in Florida last year was traced back to infected lettuce found in salad kits, affecting hundreds.
Comprehensive data on cyclospora outbreaks is limited, but available statistics indicate that very few outbreaks over the past two decades have exceeded 1,000 cases. Notably, a 1996 outbreak involving Guatemalan raspberries affected nearly 1,500 individuals, while a 2019 incident linked to Mexican basil sickened over 2,400 across the U.S. and Canada.
How can you protect yourself from cyclosporiasis?
The most effective way to avoid this parasitic infection is to steer clear of potentially contaminated food and water.
It’s crucial to thoroughly wash fresh produce before consumption; however, because cyclospora can adhere to certain foods, washing may not completely eliminate the risk. Items with crevices—like raspberries, blackberries, lettuce, spinach, cilantro, and green onions—are particularly prone to harboring the parasite.
As health officials work to identify the source, they advise buying whole heads of lettuce instead of pre-washed, bagged products and recommend removing the outer leaves before rinsing the rest under running water.
Additionally, cooking vegetables may help kill the pathogen and reduce the risk of infection.
