Soft cheese is currently under investigation as the possible source of an ongoing outbreak of listeria.

The U.S. Centers for Disease Control and Prevention (CDC) is currently investigating a multi-state outbreak of listeriosis—a serious infection caused by the bacteria Listeria monocytogenes—that’s linked to soft cheese. So far, 24 people in nine states have been infected in this outbreak, which experts have been following since 2010. Among those 24 people, 21 were hospitalized and one death reported in Ohio. In five of the cases, the women were pregnant, and one lost her fetus.

The CDC maintains a national database of the DNA fingerprints of bacterial strains from infected people in order to identify possible outbreaks. The agency noticed an increase in one rare DNA fingerprint of listeria popping up in the system in August, and, using whole genome sequencing technology, discovered that four other DNA fingerprints were also closely related genetically and possibly connected to infections that were reported five years ago.

So far, cases of sickness have been reported in California, Colorado, Illinois, Massachusetts, Michigan, New York, Ohio, Tennessee and Washington. The CDC says it has not conclusively determined the source of the outbreak but that the majority of sick people said they ate soft cheese before they became sick. Four out of the seven people who were ill and named a specific brand of cheese that they ate referred to brands that were distributed by Karoun Dairies, which has now launched a voluntarily recall and is no longer producing certain cheeses due to possible contamination.

The names of the brands that the cheese was sold under are Karoun, Arz, Gopi, Queso Del Valle, Central Valley Creamery and Yanni. The types of cheeses affected include goat, fresco, cotija, feta, mozzarella, paneer, string cheese and more. You can see a detailed list of affected products here.

“Karoun Dairies was made aware of a possible association of their cheese products with several recent cases of listeriosis by FDA and CDC,” the company said in a statement. “The company has ceased distribution of above cheeses and is working closely with FDA to continue to investigate the problem further.”

This article originally appeared on Time.com