Cyclosporiasis Outbreak Slowing? Test-Makers Hopeful 2026

The cyclosporiasis outbreak in the US may be slowing, according to test-makers, as new data shows a decline in parasite positivity rates. With over 18,000 suspected and confirmed cases, this is the largest recorded outbreak, and public health officials are cautiously optimistic. The Midwest has been hit hardest, with nine states linked to iceberg lettuce from Taylor Farms’ Mexico operations.

What the Latest Data Shows

bioMerieux, the French maker of a gastrointestinal panel that tests for 22 illnesses, publishes Syndromic Trends. Their data indicates that parasite-related illness peaked in mid-July with a 15.6% positivity rate. In the same week in 2025, the rate was just 2.9%, highlighting this year’s unusual spike. However, the company notes that increased public awareness has led to more people getting tested, which could artificially lower positivity rates if many negative results come in.

John Osiecki, vice-president of medical affairs at bioMerieux, remains hopeful: “I’m feeling confident we’re heading in that direction, but we need to continue to monitor this as we go forward.” He also mentioned hearing people request no lettuce in social settings, a sign that awareness is driving behavior change.

CDC Data vs. Test-Maker Data

The Centers for Disease Control and Prevention (CDC) provides more definitive but slower data. They have confirmed 6,707 cases acquired in the US, with 11,500 more awaiting confirmation through interviews. This lag means the CDC’s numbers are more reliable but less timely. The test-maker’s data, while faster, carries caveats about testing volume and population bias.

Key Takeaways for Consumers

• Cyclosporiasis is a parasitic infection that causes severe gastrointestinal distress, often from contaminated produce.
• Always wash produce thoroughly, but note that iceberg lettuce from Taylor Farms’ Mexico operations has been recalled.
• If you experience prolonged diarrhea, fever, or fatigue, seek medical testing, especially if you live in the Midwest or have traveled there.
• Watch for updates from the CDC, as their data will confirm whether the outbreak is truly slowing.

Why This Matters

Cyclosporiasis typically spikes in summer, but this year’s outbreak is an outlier. The decline in positivity rates could signal that contaminated products are being removed from the supply chain, but it’s too early to declare victory. Public health officials emphasize continued monitoring, as the parasite has a 1-2 week incubation period, meaning new cases may still emerge.

For now, the advice remains the same: practice good food safety, stay informed about recalls, and consult a healthcare provider if you develop symptoms. The test-maker’s optimism is a positive sign, but the CDC’s confirmation is the gold standard.

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