Here is how cyclospora outbreak is affecting businesses

Foot traffic to popular food and restaurant chains has declined as the outbreak of cyclosporiasis, linked to lettuce from Mexico, grows in scope, and consumers take steps to avoid getting sick.

Cases of illness connected to the cyclospora parasite expanded to four more states, bringing the total number of affected states to nine, the U.S. Department of Health and Human Services told CBS News on Friday. It's also been linked to at least one additional, but yet-to-be-identified food product, the Food and Drug Administration said Thursday.

Grocers and restaurant chains featuring lettuce-heavy menus have experienced a drop-off in visits in the wake of cyclosporiasis, which causes explosive diarrhea, spreading across the U.S.

Data provided to CBS News from foot traffic analytics platform Placer.ai shows that consumers are shying away from eating greens and even avoiding some establishments altogether amid the outbreak.

On July 18, the most recent date for which statistics are available, visits to fast casual restaurant chains like Cava, Chopt, Chipotle, Panera, and Sweetgreen were all down compared to an average Saturday between January 1 and July 6. Visits to Taco Bell, which served the lettuce under recall at some of its locations before removing it from store menus, dropped the most dramatically, by nearly 30%.

Sweetgreen addressed its customers in a post on social media platform X, outlining its standard food safety protocols, while assuring the public that the restaurant chain "has not been identified in connection with the current cyclospora outbreak." The company said its own food safety experts are keeping a close eye on the situation.

On Wednesday, Taco Bell announced a promotion on Instagram, featuring $1 lettuce-free enchiritos. The social media post did not cite the cyclosporiasis outbreak in introducing the deal, and it's unclear if it drew more customers into Taco Bell restaurants.

Grocers also say consumers are buying less lettuce as a precautionary measure, denting sales. Stew Leonard's, with eight grocery stores across New York, New Jersey and Connecticut, told CBS News that lettuce sales are down about 11%.

"There's a lot of confusion on store floors right now," Stew Leonard's president and CEO Stew Leonard Jr. told CBS News. "Customers are asking if they can eat lettuce and shying away from it. There's hesitation in the market, and I think that's why our store sales are off."

Leonard's own advice to cautious customers is to buy hydroponic lettuce, grown in a controlled environment.

"It's grown in a greenhouse with controlled soil,