(NEXSTAR) – While the cyclospora outbreak linked to lettuce has caused thousands of cases of cyclosporiasis — and likely even more we may never know about — another outbreak with an unknown cause has increased, according to federal authorities. The cyclosporiasis cases in this outbreak have not been linked to the lettuce outbreak, and the FDA says it is still conducting traceback efforts to identify the source. Meanwhile, an additional 21 cases have been linked to the outbreak, bringing the case count to 93. While U.S. officials have said that domestically acquired cases of the "explosive" diarrhea-causing illness are linked to produce, the source of an outbreak isn't always identified. Advertisement AdvertisementThere are currently nine states linked to the outbreak caused by iceberg lettuce sourced from Mexico.