Explosive Diarrhea Outbreak: What Is Happening in the United States?
Introduction
Health officials across the United States are investigating a multi-state outbreak of cyclosporiasis, a foodborne illness caused by the parasite Cyclospora cayetanensis. The infection has attracted widespread attention because it can cause severe watery diarrhea, often described by health authorities as "explosive diarrhea."
As of mid-July 2026, confirmed cases have been reported in more than 30 states, with public health agencies continuing to investigate the source. Michigan has reported one of the largest increases in cases, while the U.S. Centers for Disease Control and Prevention (CDC) and the Food and Drug Administration (FDA) are working to identify the contaminated food responsible for the outbreak.
What Is Cyclospora?
Cyclospora cayetanensis is a microscopic parasite that infects the small intestine. People usually become infected by eating fresh produce or drinking water contaminated with the parasite.
Unlike many stomach viruses, Cyclospora infections are not commonly spread directly from one person to another because the parasite must mature in the environment before it becomes infectious.
Symptoms
Symptoms usually appear about one week after exposure, although they can take longer.
Common symptoms include:
Frequent watery diarrhea
Severe abdominal cramps
Nausea
Loss of appetite
Fatigue
Low-grade fever
Weight loss
Bloating
One characteristic of cyclosporiasis is that symptoms may improve for a short time and then return if the infection is not treated.
How Many People Have Been Affected?
The outbreak continues to grow.
Health officials have reported:
Cases in more than 30 U.S. states.
More than 1,600 confirmed CDC cases, with additional suspected cases still under investigation.
Over 140 hospitalizations.
Michigan accounting for a particularly large share of reported infections. Reporting differences mean some state totals are higher than national confirmed counts while investigations continue.
What Is the Suspected Source?
Investigators believe the outbreak is linked to contaminated fresh produce.
Items under investigation include:
Lettuce
Bagged salad mixes
Fresh herbs
Other raw vegetables
Authorities are also examining whether some illnesses are connected to meals eaten at certain restaurant locations, but no single food source has been definitively confirmed.
How Is It Treated?
Cyclosporiasis is treatable.
Doctors commonly prescribe specific antibiotics for confirmed infections. In addition, patients are encouraged to:
Drink plenty of fluids to prevent dehydration.
Replace lost electrolytes.
Rest while recovering.
Seek medical care if symptoms are severe or prolonged.
People with persistent diarrhea should consult a healthcare provider, especially if they have recently eaten fresh produce or traveled to an affected area.
How Can You Reduce the Risk?
Health officials recommend:
Washing hands thoroughly before preparing or eating food.
Rinsing fresh fruits and vegetables under running water.
Cleaning kitchen utensils and cutting boards.
Cooking foods when appropriate, as adequate heat can kill the parasite.
Seeking medical attention if diarrhea lasts more than a few days or signs of dehydration develop.
Quick Facts
| Category | Information |
|---|---|
| Disease | Cyclosporiasis |
| Cause | Cyclospora cayetanensis parasite |
| Main Symptom | Severe watery ("explosive") diarrhea |
| Spread | Contaminated food or water |
| Common Suspected Foods | Lettuce, salad greens, fresh produce |
| Person-to-Person Spread | Uncommon |
| Treatment | Antibiotics and supportive care |
Conclusion
The ongoing U.S. cyclosporiasis outbreak has highlighted the importance of food safety and rapid public health investigations. While contaminated fresh produce is the leading suspected source, investigators are still working to identify the exact origin. Most people recover fully with appropriate treatment, but early medical evaluation is important for anyone experiencing prolonged or severe diarrhea, particularly if dehydration develops.