By Nathaniel Ratnasamy, MD, Infectious Disease Physician and Gina Bailey, BSN, RN, Infection Preventionist, Blanchard Valley Health System

Cases of cyclosporiasis, a gastrointestinal illness caused by the parasite Cyclospora cayetanensis, are increasing nationwide. 31 states have been impacted so far, but Michigan and Ohio have been hit the hardest, with more than 3,000 reported cases between the two. While the exact source of the outbreak has not been identified, there are some simple steps you can take to prevent yourself from becoming infected. 

Cyclosporiasis is an intestinal infection that can cause severe, explosive diarrhea, cramping, bloating, nausea, fatigue, loss of appetite, and a low-grade fever. The infection is caused by consuming contaminated foods or water containing the Cyclospora parasite. Symptoms typically begin about a week after exposure but can develop anywhere from 2 to 14 days later.

The infection is diagnosed with a stool test. The gastrointestinal distress can last for a month or longer, with symptoms coming in waves. Because of the intensity and extended duration of illness, cyclosporiasis poses a serious danger of fluid loss and dehydration, which can lead to hospitalization. 

As of July 9, 2026, Ohio has reported 364 cases across 51 counties, with 46 people hospitalized. Northwest Ohio has the highest density of cases, with 86 cases in Lucas County, 49 in Wood County, and 23 in Wyandot County. 

As cases continue to increase in our region, it’s important to take steps to protect yourself from infection. The source of the current outbreak has not been confirmed, but investigators in Michigan say lettuce and salad greens are potential causes. Past outbreaks have been linked to other fresh produce, including basil, cilantro, raspberries, snow peas, and sweet peas. Practicing these safe food handling and preparation tips can help keep you safe: 

• Wash your hands with soap and water before and after handling raw fruits and vegetables. 
• Thoroughly wash all fruits, vegetables, and herbs under running water before eating, cutting, or cooking. Use a clean produce brush to scrub firm produce.
• Cooking produce to at least 158ºF kills the Cyclospora cayatenensis parasite, effectively preventing infection. 

Most healthy individuals will recover from cyclosporiasis on their own, but treatments are available to help improve symptoms and shorten the time of infection. If you become sick, your healthcare provider may prescribe antibiotics to treat the infection. Additionally, antidiarrheal medications can be used to help prevent dehydration, and electrolyte-replacement drinks or IV fluids may be recommended. 

It’s important to talk to your primary care provider if you experience several episodes of watery diarrhea per day and if your symptoms return or worsen after completing the prescribed antibiotics. You may need to seek emergency care if you have a weakened immune system or signs of severe dehydration, like confusion, dizziness, and dark-colored urine. 

As Cyclosporiasis continues to spread throughout Northwest Ohio, it’s important to stay up to date with current case numbers and prevention recommendations. While the infection can be serious, prevention is possible, effective treatments are available, and no deaths have been reported.