Rising Cyclosporiasis Outbreak: What You Need to Know About the Parasitic Infection

A significant outbreak of cyclosporiasis, a parasitic infection characterized by severe, watery, and explosive diarrhea, is currently spreading across several US states. While no deaths have been reported, health officials have recorded thousands of cases in recent weeks, prompting concerns about food safety and the potential for wider transmission as investigations continue.

Key takeaways

Core outbreak facts at a glance

Cause

Parasite · Food or waterborne

Cyclosporiasis is caused by Cyclospora cayetanensis, usually spread through contaminated food or water.

Course of illness

Explosive diarrhea · Days to over a month

The infection can cause explosive diarrhea and may last from a few days to more than a month if untreated.

Suspected exposure

No source confirmed · Raw produce linked before

No specific food source has been identified in this outbreak, but past outbreaks have been linked to salad mixes and fresh herbs.

Transmission limit

Not person-to-person · Faecal-oral route

The infection does not spread from person to person and is transmitted through the faecal-oral route.

Current scope of the outbreak

Public health departments across the United States are reporting a surge in infections, with Michigan, Illinois, and Ohio seeing particularly high numbers. In Michigan alone, nearly 1,000 cases were identified within a two-week period as of early July. While official data from the Centers for Disease Control and Prevention (CDC) initially tracked 145 cases through mid-June, state-level data suggests the actual number of infections is significantly higher. Many individuals may recover without seeking medical attention, meaning they are never tested or included in official case counts.

Nearly 1,000 cases

Michigan alone recorded almost 1,000 infections in two weeks, underscoring how quickly reported state totals have outpaced earlier national tracking.

Symptoms and clinical impact

Cyclosporiasis is an intestinal illness that typically manifests about one week after a person ingests the parasite. The hallmark symptom is frequent, watery, and sometimes explosive bowel movements. Other potential symptoms include loss of appetite, weight loss, stomach cramps, bloating, nausea, and fatigue. While the illness is rarely life-threatening, it can be persistent; without medical treatment, symptoms can last for several weeks or even months, and there is a possibility of relapse where symptoms return after a period of improvement.

Typical illness timeline

About one week after exposure

Symptoms usually begin around a week after the parasite is ingested.

Active illness

Frequent watery diarrhea is the hallmark symptom, often accompanied by appetite loss, weight loss, cramps, bloating, nausea, and fatigue.

Weeks or months without treatment

The illness can persist for an extended period and may relapse after temporary improvement.

Prevention and food safety

Because the parasite is transmitted through contaminated food or water, health officials emphasize the importance of safe food handling. While the specific source of this current outbreak remains unidentified, contamination often occurs at the farm or irrigation level, making it difficult to trace. Experts recommend that kitchens and restaurants thoroughly wash all raw produce. Although rinsing is not a guaranteed preventative measure, it remains a standard recommendation. If you experience symptoms consistent with cyclosporiasis, it is advised to contact a healthcare provider to discuss testing and potential treatment options, as the infection requires specific medical intervention to resolve effectively.