A listeria outbreak that triggered a recent cheese recall has contributed to the death of an elderly Nebraska woman.

A spokeswoman for the Nebraska Department of Health and Human Services confirmed Monday that the state has seen one case associated with the outbreak, which involved ricotta salata cheese.

The woman was in her late 80s and lived in west-central Nebraska. She died in July. State health officials say they were unable to confirm whether she had eaten the cheese.

Listeria is a bacterial infection usually spread through food. The U.S. Centers for Disease Control and Prevention have identified 20 cases in 13 states as of last week. Four people have died, and 19 have been hospitalized.

Frescolina Marte brand ricotta salata cheese was recalled from stores last month.