There is an increased risk of flea-borne typhus in the City of Santa Ana, a disease that can be fatal and is primarily found in fleas on cats, dogs, and other animals. Meanwhile, mosquito activity is also on the rise in Orange County, potentially due to high temperatures and rainfall. It is unclear if the mosquito and flea-borne disease risks are directly related, as separate warnings and concerns have been reported in different areas, including a West Nile virus finding in East Sacramento.