Cyclosporiasis Outbreak: Is It Slowing Down?

Current Status of Cyclosporiasis Outbreak

The cyclosporiasis outbreak in the United States has grown significantly. The midwest has been hit particularly hard in the outbreak, where public health officials have linked infections to iceberg lettuce from Taylor Farms’ Mexico operations. The Centers for Disease Control and Prevention (CDC) has confirmed 6,707 cases of cyclosporiasis acquired in the U.S., while they are waiting on data, including interviews, to confirm additional suspected cases.

Test Maker's Perspective

The French company bioMérieux, which produces a panel testing for 22 gastrointestinal illnesses, claims the outbreak might be slowing. Their data shows a decline in total test positivity rates, but this trend could be influenced by increased public awareness leading more people to take these tests.

Confidence and Caveats

John Osiecki, vice-president of medical affairs at bioMérieux, expressed cautious optimism. 'I’m feeling confident we’re heading in that direction,' he said, adding that continued monitoring is necessary. He noted that the company's data, published as Syndromic Trends, shows a peak parasite positivity rate of 15.6% in mid-July, significantly higher than previous years.

Osiecki highlighted the importance of public awareness: 'I’ve been in a lot of social settings, and I've heard people request not to have lettuce just because they’re aware of cyclospora.' However, he also pointed out that the test panel checks for four parasites, not just cyclospora, and is only covered by Medicare for immunosuppressed individuals. The tests are more prevalent in urban areas than rural ones.

Despite these concerns, Osiecki remains hopeful: 'If a large number of people take the tests and have negative results, it could be pushing down positivity rates even as the outbreak continues.' However, the data from bioMérieux has some limitations. The panel tests for four parasites, not just cyclospora; Medicare, one of the nation’s largest insurers, only covers the panel for people who are immunosuppressed (the test costs $417); and the tests are more likely to be available in population centers than in rural areas.

By contrast, CDC data takes longer but is published with a high degree of certainty. The same week in 2025 had a parasite positivity rate of 2.9%, compared to the peak of 15.6% seen in mid-July this year. This stark increase suggests cyclosporiasis is more prevalent than previously known.

Additionally, some food safety researchers have warned that the outbreak may be larger than currently known. The Food and Drug Administration (FDA) is investigating several outbreaks which do not yet have a known cause, and the lettuce was sold in 27 states. In New Hampshire, not currently considered part of the outbreak, the state’s department of health identified cases of people sickened by Taylor Farms lettuce from Mexico as recently as mid-July, linked to a hospital cafeteria in Keene.

Public health officials continue to monitor the situation closely, emphasizing the need for ongoing vigilance and comprehensive testing. The cyclosporiasis outbreak remains a significant public health concern, with potential implications for food safety practices across the country.

Source: The Guardian