According to the University of California’s Agriculture and Natural Resources department:

“Ground squirrels are associated with the spread of Rocky Mountain spotted fever, rat bite fever, tularemia, Chagas’ disease, adiospiromycosis, and encephalomyocarditis. Notably, they can serve as reservoirs for sylvatic (bubonic) plague, a highly infectious disease caused by the bacteria Yersinia pestis…People and their pets can get plague if they visit or live in areas where ground squirrels or other rodents are infected.”