Explosive Diarrhea Parasite Spreads Across America Ahead of Independence Day

Explosive Diarrhea Parasite Spreads Across America Ahead of Independence Day

It’s almost Independence Day, which usually features barbecues, beach trips, and fireworks.

However, this year, it also includes a stomach-wrenching parasitic outbreak that federal health officials cannot explain.

As of mid-June, the CDC has confirmed 145 cases of Cyclospora cayetanensis — a microscopic gut parasite that causes explosive, watery diarrhea, brutal cramping, nausea, fatigue, and weeks of misery — sickening people across 20 states, with 20 hospitalizations and, fortunately, no deaths.

According to the CDC, 145 people ranging in age from 5 to 86 years and from 20 states contracted the parasite Cyclospora cayetanensis between May and June 16, with 20 hospitalized.

Fortunately, there have not yet been any deaths.

Since none of the patients had traveled recently, officials believe the cause is food — although they’re unsure of the exact source.

Mystery of explosive diarrhea parasite outbreak in the US – as experts try to figure out what's causing it https://t.co/7CRM7xuQ49 pic.twitter.com/TRORsgyAeL

— New York Post (@nypost) June 30, 2026

Cyclospora cayetanensis is a coccidian protozoan parasite, which means it is a single‑celled parasite that must live inside the cells lining a human’s intestine and reproduces by forming hardy, infectious spores called oocysts. Humans are the only host for this microbe. Infection occurs when a person ingests sporulated oocysts in contaminated food or water, and the fecal-oral route is strongly suspected.

Cyclospora is the kind of parasite you expect to pick up by sipping untreated water or eating a contaminated fruit in a tropical country. In other regions, infections occur when contaminated food is eaten (e.g., berries, as in an earlier outbreak in this country).

The Centers for Disease Control and Prevention (CDC), the Food and Drug Administration (FDA), and local health authorities have been conducting interviews, traceback investigations, and multi-agency coordination for weeks to determine the source of the outbreak.

Their conclusion so far? The food source remains completely unidentified, and cases have been hard to diagnose.

Summer is peak season for Cyclospora cayetanensis in the United States. Previous outbreaks have been linked to bagged salad kits, fresh cilantro, basil, and leafy greens — but traceback in this investigation has not yet identified a specific food product or supplier.

…Cyclospora is frequently missed by both patients and physicians because it is not part of a standard stool culture. Most clinical labs do not routinely test for Cyclospora unless it is specifically requested. This means many cases — perhaps the majority — are never diagnosed, giving patients and their doctors the impression they have a prolonged viral illness when a treatable parasitic infection is actually the cause.

The parasite also has an unusually long incubation period — about one week after exposure — and produces illness that can last weeks to months if untreated. The combination of these factors makes Cyclospora substantially different from typical food poisoning, and understanding those differences is essential for people who develop summer diarrhea after consuming fresh produce.

The CDC is working to find the source of a parasitic illness that's spreading across the country that causes "frequent, sometimes explosive, bowel movements." https://t.co/Sefko7LrY0 pic.twitter.com/e3QibsFLUy

— KTLA (@KTLA) July 1, 2026

As of the CDC’s June 16, 2026 update, confirmed Cyclospora cases have been reported across 20 states and Washington, D.C.: New York, Texas, Illinois, Massachusetts, Connecticut, Rhode Island, Delaware, Maryland, Pennsylvania, Virginia, North Carolina, Ohio, Tennessee, Wisconsin, Georgia, Florida, Louisiana, Colorado, Alaska, and New Jersey.

Separately, Michigan is investigating its own cluster of over 150 cases across seven southeastern counties that emerged after the CDC’s national snapshot was taken, bringing the real-world footprint of this outbreak well beyond the official 20-state tally.

Health officials in Michigan are investigating a “sudden and large” increase in cases of cyclosporiasis, the Michigan Department of Health and Human Services told TODAY.com.

Since June 22, 2026, more than 170 cases of cyclosporiasis have been reported in southeast Michigan — up from 150 several days prior. That’s out of the norm for the state, officials say. “Michigan typically identifies 50 cases a year,” a spokesperson for MDHHS said.

Cyclosporiasis is a seasonal illness in the U.S., and cases usually peak between May and August, per the CDC.

It’s not uncommon to see infections increase in the summer. However, the latest spike in Michigan has health officials on high alert and urging people to seek care if they experience symptoms.

Past outbreaks have been traced to imported cilantro from Puebla and bagged greens distributed through major national retail chains. In 2018, McDonald’s salads were linked to over 3oo cases of cyclospora.  The current geographic spread is strongly suggestive that we are looking for a nationally distributed food item, most likely fruit or vegetables.

Until then, eat more meat (that has been properly grilled), drink plenty of alcohol, and try to stay healthy for America’s 250th birthday.

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