Centuries ago, of course, fleas spread terror and death through Europe, in the form of a type of bacteria that lives in the blood of rodents. The bacterium causes bubonic plague, and it killed a fourth of the European population from 1347 to 1352. The plague lives on and is still occasionally transmitted by fleas. But human cases are rare in the United States, thanks to sanitation and rat control, and those that crop up are easily treated with antibiotics. Still, fleas can transmit other infectious diseases, including the flu-like murine typhus.
Various strategies exist for getting rid of fleas.
It's best to check with a veterinarian, since finding the best method to combat them depends on individual circumstances. Some flea populations have evolved strong resistance to certain pesticides. P.O. Box 11626, Santa Ana, CA 92711.