Taco Bell has seen a sharp drop in customer traffic in recent days amid a nationwide outbreak of cyclosporiasis, a gastrointestinal illness federal investigators have linked to lettuce supplied to the chain, according to new data.

Foot traffic fell steeply late last week. On Friday, July 17, visits to U.S. Taco Bell locations were down 30.9 percent compared with this year’s average for that day of the week, according to Placer.ai data shared with The Independent. On Saturday, July 18 — the most recent date where data is available — traffic was down 29.8 percent.

The downturn marks a significant shift from the prior weekend. On Friday, July 10, traffic was down 4.6 percent, followed by a 5.8 percent decline on Saturday, July 11.

Other fast-casual chains — including those known for serving leafy greens — have also seen declines in foot traffic.

On Saturday, July 18, Chopt recorded a 24 percent drop in visits. Panera Bread saw a 9.1 percent decline, while Chipotle was down 5.9 percent. Sweetgreen and Cava each posted more modest decreases of 4.7 percent.

The declines come as cases of cyclosporiasis — an illness caused by consuming the microscopic cyclospora parasite — have surged. According to the Centers for Disease Control and Prevention, there have been 4,173 confirmed cases across 41 states, nearly four times the average annual total. Michigan health officials have reported 6,571 cases, the highest in the country.

While not life-threatening, infections can lead to a range of unpleasant symptoms, including “explosive” bowel movements, vomiting, fever and fatigue. Symptoms, which can take more than two weeks to appear, typically resolve without treatment, according to the CDC.

Taco Bell has been tied to the outbreak by federal officials.

On July 16, the FDA said it had linked cases of cyclosporiasis to shredded iceberg lettuce served at Taco Bell locations in five states, including Michigan. The following day, the agency said it had identified Taylor Farms as the supplier used at locations where sick customers had eaten.

Acting out of an “abundance of caution,” Taylor Farms issued a voluntary recall of all iceberg lettuce sourced from central Mexico. The same day, Taco Bell said it had removed Taylor Farms lettuce from its supply chain.

“We believe public health is a shared responsibility among restaurants, their suppliers, and authorities, and we are proud to have consistently acted quickly and proactively to protect our guests,” Taco Bell said in a statement.

The Independent has contacted the fast-food chain for comment.

The federal investigation, however, prompted confusion this week after the FDA announced a “false positive test.” Still, the agency said reevaluating the sample did not alter the data underpinning the advisory that led to the Taylor Farms recall.

“To clarify, this false-positive lab sample DOES NOT change the basis for FDA’s ongoing outbreak investigation or the overwhelming epidemiological data supporting the current voluntary recall by Taylor Farms,” the agency wrote on X.

To date, no positive tests have been confirmed from any source, and the origin of the nationwide outbreak remains under investigation, the agency said. On Tuesday, HHS Secretary Robert F. Kennedy Jr. said the outbreak was “under control.”