Taco Bell has admitted sales took a hit from a cyclosporiasis outbreak linked to contaminated lettuce that sickened thousands with symptoms including explosive diarrhea, but executives say they have a plan to win customers back.

Sales slipped about 2 percent at Taco Bell stores through its third financial quarter, Ranjith Roy, chief financial officer of parent company Yum Brands, said during the latest earnings call last Thursday, according to Restaurant Dive.

Before the cyclosporiasis outbreak began May 1, Taco Bell reported a 7 percent increase in same-store sales for the second quarter, which ended June 30, marking its ninth straight quarter of outperforming industry averages. The chain saw its biggest sales drop around the weekend of July 18 after it announced it was removing potentially contaminated lettuce from restaurants.

Customer visits to Taco Bell locations nationwide were also down, dropping 21 percent by July 23 compared to the daily average for the year, according to market research firm Placer.ai.

Public health officials have linked the cyclosporiasis outbreak to lettuce supplied by Taylor Farms, including shredded lettuce served at Taco Bell restaurants in at least nine states. Nearly 2,000 cases have been tied to Taco Bell, the Centers for Disease Control and Prevention said. Symptoms of the illness, which is caused by the parasite cyclospora, include frequent watery diarrhea, which can last for a month or longer, severe fatigue and stomach cramps.

Two people in Michigan who contracted cyclosporiasis have died, the Health and Human Services Department said Monday. The number of confirmed and suspected cases has reached almost 20,000 across the U.S. Health officials believe that contaminated produce from other sources may also be playing a role.

“We’ve seen real improvement as consumers have understood better the nature of the issue, and they understand that it is not a Taco Bell-specific issue,” Yum Brands CEO Chris Turner said during the call.

Turner added that removing the affected lettuce and keeping customers updated helped restore trust in the brand. He also said that customer sentiment has already bounced back, with some measures showing consumers view Taco Bell more positively than they did before the outbreak, though he did not specify which measurements.

To bring back customers, Turner said Taco Bell relied on its “magical formula” of digital engagement, value deals and popular promotions to rebuild sales momentum.

This includes the recent “Tuesday Drops” offers featuring a $1 Enchirito and $1 Mexican Pizza, which were the highest-performing in the chain’s history, Turner said.

The August 4 offering includes a $1 Meximelt for all customers and $1 Regular Nacho Fries exclusively for rewards members.