Shares of Yum! Brands Inc. (YUM), the parent company of Taco Bell, slipped overnight as investors weighed the potential impact of a widening investigation into the Cyclospora outbreak, which prompted the fast-food chain to temporarily remove select fresh ingredients from some restaurants.

Investigation Focuses On Taco Bell's Possible Connection 

Federal and state authorities are examining whether Taco Bell locations may have contributed to a growing outbreak of cyclosporiasis, a foodborne illness linked to a parasite that can contaminate produce.

According to a Washington Post report, investigators have not confirmed a source, but officials are reviewing possible connections as cases continue to rise across the country.

Cyclospora is a parasite that affects the intestinal system and can cause prolonged watery diarrhea, stomach discomfort and other digestive symptoms. The infection typically spreads through contaminated food or beverages and does not pass directly between people.

The Centers for Disease Control and Prevention (CDC) said in a statement that the Cyclospora outbreak has spread across at least four Midwestern states—Michigan, Ohio, West Virginia and Kentucky. More than 400 people have become sick since late June, but officials believe the actual number is likely higher.

Taco Bell Expands Precautions 

Taco Bell temporarily removed some fresh ingredients from select restaurants as a precaution during the outbreak, according to a Bloomberg report. The company said there is no confirmed link between Taco Bell and the outbreak and that it took the step voluntarily, following guidance from health officials.

Some Taco Bell franchise locations in Michigan also temporarily stopped serving lettuce.  inched 0.6% lower overnight, heading into Wednesday.

Yum! Brands Undergoes Business Restructure

Apart from the health investigation, Yum! Brands is reshaping its business after recently  to sell its Pizza Hut operations in two deals worth $2.7 billion, allowing it to focus more on its Taco Bell and KFC brands.

Yum is also investing heavily in its digital business, with online sales reaching nearly $11 billion in the first quarter, or 63% of total global sales. As Taco Bell continues to post strong sales growth, Yum aims to expand its technology-driven franchise business ahead of its second-quarter earnings report expected on July 30.

Analysts see $2.19 billion in revenue with earnings of $1.56 per share, according to Fiscal AI data.

YUM Retail Traders View 

On Stocktwits, retail sentiment around the stock jumped to ‘bullish’ from ‘bearish’ territory the previous day, with an 800% rise in message volume over the past week.

YUM stock has gained over 4% year-to-date.