Health officials investigating the large outbreak of diarrhea caused by the parasite cyclospora say they have “very strong” evidence that shredded iceberg lettuce supplied by Taylor Farms is the likely source, despite a false positive test for the parasite over the weekend.

Taylor Farms is removing iceberg lettuce sourced from central Mexico after multiple reports citing unnamed sources linked its lettuce to an outbreak.

Taylor Farms said it's removing iceberg lettuce from Mexico due to the cyclospora outbreak, which has affected at least 1,644 people across 34 states.