Investigators acknowledged they have no proof as to what is causing the cyclosporiasis outbreak that has sickened an estimated 7,000 people.

The FDA issued an update on the cyclospora outbreak in the United States late Friday, confirming that a single supplier has been identified as the source.

Taylor Farms de Mexico lettuce sample tested positive for cyclospora, FDA said, as officials investigate a multistate outbreak of the parasite.

We still don’t know the source of the outbreak.

As of Sunday, the FDA said there are no confirmed positive sample results for Cyclospora.