Duke University researchers report that samples isolated from Chobani yogurt that was voluntarily recalled in September 2013 have been found to contain the most virulent form of a fungus called Mucor circinelloides, which is associated with infections in immune-compromised people.

The study by Duke University scientists shows that this strain of the fungus can survive in a mouse and be found in its feces as many as 10 days after ingestion.

In August and September 2013, more than 200 consumers of contaminated Chobani Greek Yogurt became ill with vomiting, nausea and diarrhea. The U.S. Food and Drug Administration (FDA) analyzed the contaminant and identified it as the mold Mucor circinelloides.

On September 5, 2013, Chobani voluntarily recalled eight product lines that had been distributed nationwide from its Twin Falls, Idaho facility. The facility was shut down and thoroughly cleaned. Chobani said at the time that the mold was naturally occurring and not considered a food-borne pathogen.

This study, which appears July 8 in the online, open access journal mBio, indicates that the particular strain of fungus found in the yogurt may pose a more serious threat to public health than previously thought, said Dr. Joseph Heitman, a senior author of the study and professor and chair of molecular genetics and microbiology at Duke’s School of Medicine.

Heitman said the finding also suggests specific attention should be paid to fungal pathogens in food products and the factories that manufacture them.