Taco Bell is taking a more aggressive approach to guard against cyclospora than federal health officials currently recommend, temporarily removing some ingredients from select restaurants while the CDC investigates a multistate outbreak.

The fast-food chain told Business Insider on Tuesday that it has “voluntarily and temporarily” removed certain ingredients from select restaurant menus as a precaution against the outbreak of diarrheal disease.

Taco Bell said the measure is precautionary. Health officials have not confirmed a link between the parasite and Taco Bell, any specific ingredient, supplier, restaurant or retailer.

The Taco Bell spokesperson did not respond to questions about which specific products were removed or which Restaurants were affected. Cases have been reported in 31 states since May 1 and are suspected to be linked to contaminated fresh produce, particularly leafy green vegetables and herbs.

Social media posts from customers at some Taco Bell locations in the Midwest indicate that lettuce, cilantro, onions, tomatoes and their mix-ins, such as guacamole and pico de gallo, are temporarily unavailable.

The move goes a step beyond current CDC guidance, which advises consumers to wash produce thoroughly before consuming it, but adds that there is no guaranteed way to avoid cyclospora because it is often impossible to know if fresh produce was contaminated.

“The health and safety of our guests is our top priority,” a Taco Bell spokesperson said in a statement. “As authorities continue their broader review, Taco Bell has voluntarily and temporarily removed limited ingredients at select restaurants as a precautionary measure.”

The caution reflects how much is at stake for restaurant chains when foodborne illness outbreaks are linked to their brands.

Chipotle spent years recovering after its 2015 E. coli and subsequent food safety crises hit sales and customer confidence. Taco Bell has also weathered major outbreaks before: In 2006, an E. coli outbreak sickened dozens of people across the Northeast and was ultimately traced to contaminated products in its supply chain, prompting widespread scrutiny of the brand.

Taco Bell did not say what motivated the precautionary recalls beyond the ongoing public health investigation, and federal officials have not publicly identified any restaurant chain as the source of the outbreak. The CDC did not immediately respond to a request for comment.

The latest round of precautions is tied to a CDC investigation into a multi-state outbreak of cyclosporiasis, a disease caused by exposure to the microscopic parasite Cyclospora cayetanensis. which can cause prolonged watery diarrhea, fatigue, stomach cramps, and other gastrointestinal symptoms.

Business Insider previously reported that public health experts suspect contaminated fresh produce to be the cause of the outbreaks because cyclospora is most commonly transmitted through food or water contaminated with the parasite.

The disease can be treated with antibiotics, but can last for weeks without treatment.