(Siphonaptera : Pulicidae)
Facts: Adult fleas are legendary for their jumping ability.
The cat flea, Ctenocephalides felis (Bouché), is the most common flea pest of dogs and cats in Texas.
Adults can be found on the pet and sometimes move to humans for a blood meal.
Flea larvae are small, elongate, and thin.
The larvae are found in the yard or around the pet bedding area and they feed on skin flakes, hair and other organic matter.
Historically, fleas have been involved in devastating epidemics of plague throughout the world. Today in the U.S., fleas primarily are annoying biting pests of pets and people. The most common species is the cat flea, Ctenocephalides felis. However, other species of fleas that are parasites of rodents are involved in the transmission of plague and murine typhus, both of which occur in the southwestern U.S. You are encouraged to learn more about the biology of fleas, especially the cat flea, so that you can make more informed decisions about health risks to you and your pets, how to avoid being bitten, how to prevent or suppress infestations, and whether flea control is warranted in and around your residence.
Is the Cat Flea a Public Health Risk?
Bites of cat fleas can be very annoying to humans because chemicals in flea saliva stimulate an immune response that causes itching. The same immune response can be much more severe in dogs and cats, possibly producing a serious allergic response known as flea bite allergy in susceptible pets. You should take pets suffering from this condition to a veterinarian for treatment and consultation about approaches to flea control.
Cat fleas also are one of the hosts of the double pore dog tapeworm, Dipylidium caninum. This tapeworm is a parasite of dogs and cats, but it can infect children who ingest a cat flea in which an immature stage of the tapeworm exists. The immature stage of the tapeworm emerges from the ingested flea and begins to develop in the intestine of the child. This tapeworm does not cause obvious symptoms and is not a cause of serious disease, but you should consult with a physician if an infection is suspected. The most obvious sign of infection in a child is the appearance of a stage of the tapeworm, known as a "proglottid," in a child's bowel movement. A proglottid is whitish, about the size and shape of a pumpkin seed, and capable of undulating movements.
Other Fleas That Are A Public Health Risk
The flea that is the most significant risk to human health worldwide is the Oriental rat flea, Xenopyslla cheopis. This flea is a parasite of rats in the genus Rattus, but also feeds readily on humans and is a highly efficient vector of plague.
A flea of potential importance to vacationers in subtropical and tropical areas is the so-called "chigoe flea," Tunga penetrans. Larvae of this flea develop in sandy soil usually associated with pigs and pig feces. However, chigoe fleas also are found in the sand of coastal beaches, which explains another common name, "sand flea." Female T. penetransinfect people by penetrating into tender flesh between toes or into the soles of the feet. There, the 1-mm long females become embedded, begin to suck blood, and eventually develop eggs. As they do, their body swells about 80-fold, reaching the size of a pea and causing intense pain. Sites of infestation may become infected with bacteria and, if untreated, may eventually require amputation. The best prevention for vacationers is to avoid going barefoot in regions where this flea is common, including on beaches associated with the Caribbean Sea.
How Many Types of Fleas Are There?
There are an estimated 2,500 species of fleas in the world, approximately 325 of which occur in the continental U.S. Over 94% are associated with mammals, and nearly 6% with birds. At least 30 species of fleas have been found on mammals in Indiana, but only the cat flea is a serious pest of pets, livestock, and humans. Despite its common name, the cat flea is the primary flea that infests dogs. A closely related flea with the scientific name Ctenocephalides canis (the so-called "dog flea") exists throughout the world, but is rarely found on pets in Indiana.
How Can I Recognize a Flea?
Adult fleas typically are about 1/8 inch long, oval, and reddish-brown. They are wingless, and their bodies are very thin, so thin that they can move freely through fur or feathers of their host. They possess very large hind legs that are used for jumping and a very slender proboscis (beak) that extends forward when the flea takes a blood meal. At rest, the proboscis projects downward and backwards between the legs, but it cannot be seen without the aid of a microscope. Similarly, recognition of flea larvae and pupae typically requires the use of a microscope. To the unaided eye, the legless larvae resemble tiny whitish "worms." Flea pupae most likely would not be recognized at all because they are encased within a sticky cocoon covered by incorporated soil particles and small items of debris from the habitat in which the larvae develop.