DDPHE Blog: What Denver Residents Should Know About Cyclosporiasis

DDPHE Blog: What Denver Residents Should Know About Cyclosporiasis

Published on July 09, 2026

Have you had diarrhea that won't go away? It could be cyclosporiasis, an illness caused by a microscopic parasite called Cyclospora. Cases of cyclosporiasis increase during the spring and summer and is often associated with international travel to regions where Cyclospora is common and present every year. Health officials across the United States are currently investigating a rise in illnesses caused by Cyclospora.

The Centers for Disease Control and Prevention (CDC) has received several hundred reports of cases of cyclosporiasis across 18 states in people who became sick after eating food in the US. Cyclosporiasis is an illness that healthcare providers and laboratories must report to public health for investigation, and DDPHE investigates cyclosporiasis in people who live in Denver. DDPHE has investigated 16 cases so far in 2026 and around 70% have been associated with international travel.

The most common symptoms of cyclosporiasis are:

• Watery sometimes "explosive" diarrhea.
• Loss of appetite.
• Weight loss.
• Stomach cramps.
• Gas and bloating.
• Fatigue.
• Nausea.

Symptoms usually begin about one week after ingesting Cyclospora but can appear anywhere from two to 14 days later.

Cyclosporiasis is spread by eating or drinking food or water contaminated with the Cyclospora parasite. Fresh fruits, vegetables and leafy greens are the foods most often linked to cyclosporiasis outbreaks. Unlike many stomach illnesses, it is very unlikely to spread directly from one person to another.

People can become infected by:

• Eating fresh produce contaminated with the parasite.
• Drinking contaminated water.
• Eating contaminated food while traveling, especially in tropical or subtropical areas.

Without treatment, the illness can last from a few days to more than a month, and symptoms may come and go. Some people, especially those with weakened immune systems, may become more seriously ill. If you have symptoms of cyclosporiasis, contact your health care provider. The infection can be treated with antibiotics. Drinking plenty of fluids is also important to help prevent dehydration.

You can help protect yourself and your family by:

• Washing your hands with soap and water before eating or preparing food and after using the restroom.
• Washing fruits and vegetables before eating or preparing them. While washing produce may not remove all Cyclospora, it is still an important food safety step.
• Cooking foods thoroughly, when possible, as heat kills the parasite.
• Drinking safe, clean water.
• Practicing safe food handling by keeping preparation surfaces clean and refrigerating food properly.

If you become sick, you can also help prevent contamination by:

• Staying home if you have diarrhea until your symptoms have improved.
• Avoiding preparing food for others while you are sick.
• Washing your hands thoroughly after using the restroom.
• Avoiding gardening or handling fruits and vegetables intended for others until you have recovered.

If you think you became sick after eating food in Denver, contact your health care provider and report your illness to the DDPHE. Reporting suspected foodborne illness helps public health investigators identify potential outbreaks, investigate possible sources and protect others from becoming sick. You can also learn more about safe food handling and preventing foodborne illness by visiting DDPHE's food safety page.

• Public Health & Environment