The U.S. Food and Drug Administration says its inspectors have detected the Cyclospora parasite at a Mexican farm identified as the source of a lettuce-borne outbreak in the United States. The FDA says the finding follows the period of illnesses reported earlier.

Officials say the detection is based on sampling at specific locations on the farm. The reports state that inspectors found Cyclospora in two areas, including a wastewater tank and a drainage ditch used for lettuce cultivation. The FDA says it is still unclear how the lettuce became infected.

The Guardian notes the announcement comes after the U.S. Centers for Disease Control and Prevention declared the outbreak over, adding context about the overall scale. Multiple outlets report that the episode sickens nearly 13,000 people and is linked to Taylor Farms lettuce. The differing emphasis across outlets is mostly on where the parasite was found and on the timing relative to public health officials’ declaration that the outbreak has ended.