Public health officials set traps in Santa Ana to catch animals suspected of being hosts to typhus-carrying fleas.
Robert Cummings with the Orange County Vector Control District said the flea count is among the highest he's ever seen.
"Lots of fleas, more likely there's a chance that these fleas will transmit the disease to somebody," said Cummings.
Fleas capable of carrying typhus were found on animals including possums. The animals were located in a neighborhood, near two schools, where a resident had to be hospitalized for typhus last month. A second confirmed case of typhus was also reported in the city of Orange.
Willard Intermediate School and El Sol Science and Arts Academy in Santa Ana started using a flea-prevention spray around campus as a precaution.
"It's completely harmless to humans, to other animals. It focuses and targets the fleas," said Arturo Jimenez with the Santa Ana Unified School District.
A flea prevention event was scheduled for Saturday at Willard Intermediate School to educate the public.
"If we can control the population now when flea season is here, we're hoping to reduce that risk so no one else gets sick," said Jose Gonzalez, a spokesman for the city of Santa Ana.
Symptoms usually appear a week or two after exposure and can include high fever, headaches, chills, body aches and pains and a rash. It can be treated with antibiotics, but if it's left untreated, the disease can be deadly.
Authorities are urging residents to treat pets with flea prevention medication and get rid of places where animals can find shelter and food.