Cyclospora Is in the Headlines This Summer — Here’s What Cape Cod Residents Should Know

Published on: July 14, 2026

Summer on Cape Cod means farmers markets, garden salads, and berries by the pint — but this year it also comes with a parasite in the national news. A tiny parasite called Cyclospora has been sickening people across the country, causing an intestinal illness known as cyclosporiasis, and Massachusetts is among the states reporting cases. While a large outbreak investigation is underway in Michigan and other states, Massachusetts officials continue to monitor seasonal cases. A few simple food-safety habits can go a long way toward reducing your risk while still enjoying the season’s produce.

What Is Cyclospora?

Cyclospora cayetanensis is a one-celled parasite far too small to see, smell, or taste. People get sick — a condition called cyclosporiasis — by eating fresh produce or drinking water that’s been contaminated with the parasite. It’s a seasonal illness in the U.S.: the CDC considers the cyclosporiasis season to run from May 1 through August 31, when we’re all eating more raw fruits and vegetables.

One important thing that sets it apart from a typical stomach bug: cyclosporiasis does not spread from person to person. The parasite needs one to two weeks in the environment before it can make anyone sick, so you won’t catch it from a family member the way you’d catch a norovirus. That also means the source is almost always something that was eaten or drunk — not a sick contact.

What Are the Symptoms?

Symptoms usually show up about a week after exposure, sometimes up to two weeks — one of the reasons the illness can be tricky to trace back to a specific meal. The most common symptom is frequent, watery diarrhea that can be prolonged. Other symptoms include:

• Loss of appetite and unintended weight loss
• Stomach cramps and bloating
• Nausea and fatigue
• Less commonly: vomiting, low-grade fever, and body aches

Left untreated, cyclosporiasis can drag on for weeks and even relapse after it seems to have cleared. The reassuring part: it is very treatable. It responds to a specific course of antibiotics, and most people improve quickly once they’re on the right medication.

How Does It Spread?

Cyclospora spreads through fresh produce or water that’s been contaminated with human waste. In practice, that contamination almost always happens before food ever reaches the store — through unsafe irrigation water or poor sanitation where produce is grown, harvested, or packed — not in your kitchen.

Because the parasite is so small and can adhere tightly to produce, rinsing fruits and vegetables helps reduce risk but may not completely remove it.

Michigan health officials are currently investigating a large cyclosporiasis outbreak and have reported that early findings point to lettuce or salad greens as a possible source. However, investigators have not identified a specific type of produce, grower, or supplier, and other foods have not been ruled out. Because Cyclospora has an incubation period of up to two weeks and produce often moves through complex distribution networks, public health officials caution that it may take time to determine a definitive source.

The foods tied to previous cyclosporiasis outbreaks in the United States and Canada, according to public health officials, include:

• Fresh raspberries and other berries
• Fresh basil and cilantro
• Scallions (green onions) and snow peas
• Bagged salad mixes and leafy greens

Is It Here in Massachusetts?

In Massachusetts, 18 cases of cyclosporiasis had been reported between May 1 and July 7, according to the Massachusetts Department of Public Health. The department noted that additional cases may be identified as testing and reporting continue.

At this time, Massachusetts officials have not announced a statewide outbreak or identified a specific food source linked to those cases.

Here on the Cape, the Barnstable County Department of Health & Environment monitors reportable illnesses like cyclosporiasis year-round through the state’s surveillance system, working alongside local health departments and the Massachusetts Department of Public Health. So while Cyclospora is worth understanding, the takeaway for Cape Cod residents is straightforward: this is a good moment to brush up on produce safety, not a reason to skip the farmers market.

How Do You Protect Yourself?

The same habits that protect you from Cyclospora also help protect against a variety of foodborne illnesses. This summer, keep these tips in mind:

• Wash all fresh produce under clean, running water before eating, cutting, or cooking it — even items you plan to peel.
• Scrub firm fruits and vegetables such as melons and cucumbers with a clean produce brush.
• Pay attention to public health advisories or recalls involving fresh produce, especially lettuce and salad greens. If choosing lettuce, consider purchasing whole heads and discarding the outer leaves before washing the inner leaves under running water.
• Cook produce when appropriate. Cyclospora is resistant to routine washing and chemical disinfection, but heating food to at least 158°F (70°C) can inactivate the parasite. Cooking is the most reliable way to reduce risk when suitable for the food being prepared.
• Cut away bruised or damaged areas of fruits and vegetables before preparation.
• Wash your hands with soap and water before and after handling fresh produce.
• Clean and sanitize cutting boards, countertops, and utensils used to prepare produce.
• Avoid swallowing water while swimming as a general health precaution. However, current outbreak investigations have not identified recreational water exposure as a source of illness, and contaminated produce remains the primary focus of public health investigations.

When Should You See a Doctor?

If you have watery diarrhea that’s frequent, severe, or lasting more than a few days, contact your healthcare provider.

It’s worth noting that routine stool testing may not always include Cyclospora. If your symptoms fit and they aren’t improving, ask your healthcare provider whether testing for Cyclospora is appropriate. Specialized stool testing may be needed to identify the parasite.

People with weakened immune systems should contact their healthcare provider sooner, as they may experience longer-lasting or more severe illness.

The Bottom Line

Cyclospora is receiving increased attention this summer because of a large outbreak under investigation in Michigan and cases reported in several states. In Massachusetts, health officials continue to monitor seasonal cases and have not identified a specific source. The best protection is to wash produce thoroughly, consider peeling or cooking produce when appropriate, follow any public health advisories involving fresh produce, and contact a healthcare provider if you develop persistent watery diarrhea.

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