Felis ISSN 2398-2950

Ctenocephalides felis

Synonym(s): C. felis, cat flea

Contributor(s): Susan Dawson, Grace Mulcahy, David Scarff




  • Class: Insecta.
  • Order: Siphonaptera.

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Clinical Effects



Adult fleas

  • Parasitic - in hair coat of cat, dog or other animal.
  • Non-parasitic - in the absence of a host can survive few days to a few weeks (if has recently fed) in a cool, moist environment.
  • Pre-emerged adults in their cocoon - in the absence of stimuli to emerge (pressure, temperature, possibly vibration) - can remain in the cocoon <1 year, particularly in cool temperatures.


  • Laid on the animal but not sticky; eggs fall off within about 8 hours.
  • Majority fall where cat spends most of its time sleeping/resting, ie house/shed, in the bedding, on chairs, on the owner's bed, etc.

Larvae and pupae

  • Larvae hatch where eggs accumulate in the environment and do not move very much, although capable of moving up to 46 cm.
  • Require blood protein found in the feces of fleas.
  • Negatively phototactic, positively geotactic   →   found at the base of the carpet pile.


  • Adult   →   egg   →   larva   →   pupa   →   pre-emergent adult   →   adult  Lifecycle: Ctenocephalides canis - diagram .
  • Become active and breed at temperatures >10-15°C.
  • Pre-emergent adults will emerge in the spring, or at preferred temperature and humidity, eg when central heating is turned on.
  • Eggs, larvae and pupae develop slowly at spring temperatures, but the speed of development of subsequent generations increases, reaching about 5 weeks in the late summer.
  • Development slows down as temperatures fall and ceases in winter in an unheated house.
  • Development can continue in a centrally heated house if microenvironmental humidity is adequate.
  • Marked variation in temperatures, eg heating off at night, will increase mortality.


  • Animals become infected by:
    • Newly emerged adults in their own environment.
    • Newly emerged adults in visited environment, eg homes, gardens of other animals.
    • Adult fleas, in particular males, will transfer from one animal to another; less significant.

Pathological effects

  • At least 15 allergens in flea saliva; one hapten (4-7 kDa) binds to collagen; others that have been identified have molecular weights of 14-150 kDa.
  • Classical progression of the hypersensitivity response as described in dog:
    • Sensitization with no response.
    • Type IV nodular delayed type hypersensitivity (DTHS) reaction appearing about 6-12 hours after the bite.
    • Type I wheal and flare intermediate type hypersensitivity (ITHS) reaction within 15 minutes to a few hours of the bite; this is then followed by a DTHS reaction.
    • ITHS reaction only.
    • Possible desensitization.
  • Response in the cat:
    • Not as well characterized but ITHS, DTHS and type III basophil hypersensitivity have all been described in combination or alone in individual cats.
    • Unexposed and asymptomatic.
    • Infested and asymptomatic (in a period of sensitization or desensitization).
    • Infested showing flea bite hypersensitivity.
  • Flea infestation   →   chronic flea bites   →   hypersensitivity to flea allergens, eg salivary chemicals   →   pruritus and overgrooming  Dermatitis: flea allergic .
  • Three major dermatological syndromes:
    • Papulocrustous dermatitis (miliary dermatitis Dermatitis: miliary).
    • Symmetrical alopecia  Skin: alopecia - endocrine 03 .
    • Eosinophilic plaque formation  Eosinophilic granuloma complex , (intense pruritus precedes development of moist red papules   →   cobblestone appearance).
  • Overgrooming may be more obvious than pruritus   →   alopecia without obvious cutaneous inflammation.
  • Alopecia predominantly on the flanks, abdomen and back of the thighs.
  • Continual licking   →   damaged hair follicles   →   atrophy   →   permanent alopecia.

Other Host Effects

  • Depends on blood meals - the female ingests large volumes of blood (   →   enlarged abdomen) to maintain high fecal output (provides food in environment for larvae); the male feeds less   →   less susceptible to systemic insecticides.
  • C. felis not single-host specific, so it can breed if it feeds on dogs, cats and some wild mammals, eg foxes and badgers, but not solely on humans.
  • If hungry, the flea will feed, but not breed, on other hosts such as farm animals or human.
  • Body is streamlined for moving quickly through animal coat.
  • Specialized mouthparts for piercing skin, sucking blood and injecting saliva as an anticoagulant.


Control via animal

  • Three point strategy to control:
    • Eliminate adult flea population on animal.
    • Protect animal against reinfection.
    • Eliminate environmental reservoir of fleas (see below).
  • See Flea Control Flea: control.


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Further Reading


Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Lee S E, Johnstone I P, Lee R P et al (1999) Putative salivary allergens of the cat flea, Ctenocephalides felis felis. Vet Immunol Immunopathol 69 (2-4), 229-237 PubMed.
  • Marsella R (1999) Advances in flea control. Vet Clin North Am Small Anim Pract 29 (6), 1407-1424 PubMed.
  • Fisher M A, Jacobs D E, Hutchinson M J et al (1996) Evaluation of flea control programmes for cats using fenthion and lufenuron. Vet Rec 138 (4), 79-81 PubMed.
  • Dryden M W & Rust M K (1994) The cat flea: biology, ecology and control. Vet Parasitol 52 (1-2), 1-19 PubMed.
  • Heath A W, Arfsten A, Yamanaka M et al (1994) Vaccination against the cat flea Ctenocephalides felis felis. Parasite Immunology 16 (4), 187-191 PubMed.
  • Rust M K (1994) Interhost movement of adult cat fleas (Siphonaptera: Pulicidae). J Med Entomol 31 (3), 486-489 PubMed.
  • Opdebeeck J P & Slacek B S O (1993) An attempt to protect cats against infestation with Ctenocephalides felis using gut membrane antigens as a vaccine. Int J Parasitol 23 (8), 1063-1067 PubMed.