NBC Chicago News reports that Illinois Department of Public Health will investigate a salmonella outbreak that has affected dozens of residents in Kane County over the past year, officials said.

The source of the outbreak has not been located, and it’s not related to a national strain linked to peanut butter, said Claire Dobbins, the Kane County Health Department’s director of preparedness and communicable disease control.

Since January 2006, there have been 35 confirmed cases of salmonella serotype Newport in Kane County — 22 of which occured among Hispanic residents.