Fleaborne Diseases of the United States

In the United States, some fleas carry pathogens that can cause human disease, including:

  • Plague — most commonly transmitted to humans in the United States by infected ground squirrel fleas, Oropsylla montana, and globally by infected Oriental rat fleas, Xenopsylla cheopis. Also, may be transmitted by improperly handling an animal infected with plague bacteria. Most U.S. cases occur in rural areas of the western United States.
  • Flea-borne (murine) typhus — transmitted to people by infected cat fleas, Ctenocephalides felis, infected Oriental rat fleas, Xenospylla cheopis, or their feces (poop; also called “flea dirt”). Most cases in the United States are reported from California, Texas, and Hawaii.
  • Cat scratch disease (CSD) — transmitted to humans most often after a scratch from a domestic or feral cat that has been infected by a Ctenocephalides felis flea, or through flea feces (poop; also called “flea dirt”) being inoculated through a cat scratch. CSD occurs wherever cats and fleas are found.
  • Fleaborne parasites, such as tapeworms can spread to people and animals if they accidentally swallow an infected flea. Small children are at a higher risk than adults, as they may spend more time close to the floor and carpeted areas where fleas are found. Most infected people will not show symptoms and will not know they are carrying tapeworms.