Ctenocephalides felis, cat flea

Taxonomc lineage

cellular organisms - Eukaryota - Fungi/Metazoa group - Metazoa - Eumetazoa - Bilateria - Coelomata - Protostomia - Panarthropoda - Arthropoda - Mandibulata - Pancrustacea - Hexapoda - Insecta - Dicondylia - Pterygota - Neoptera - Endopterygota - Siphonaptera - Pulicomorpha - Pulicoidea - Pulicidae - Archaeopsyllinae - Ctenocephalides - Ctenocephalides felis

Brief facts

• The cat flea, Ctenocephalides felis, is the most common flea species and the most important ectoparasite of domestic cats and dogs worldwide. The annual expenditures by pet owners for flea control products in the United States exceed $1 billion. Other fleas commonly recovered from dogs and cats are Ctenocephalides canis, Pulex simulans, and Echidnophaga gallinacea.
• In addition to infesting domesticated dogs and cats, C. felis can infest a wide diversity of other mammalian hosts. In North America, a number of wild species are parasitized by C. felis, including coyote, red and gray fox, bobcat, Florida panther, skunk, raccoon, opossum, ferret, and several rodent species. Other animals that have been reported as hosts of the cat flea include domestic rabbits, horses, cattle, sheep, goats, jackals, poultry, and koalas.
• C. felis is unable to survive exposure to temperatures below −1°C for more than five days at any life stage. Its survival and maintenance in northern areas is likely to occur through several mechanisms:
  • the presence of adults on domestic and feral dogs and cats;
  • the presence of adults on urbanized small wild animals (such as raccoons and opossums);
  • delayed development of immature stages in freeze-protected underground dens of wildlife;
  • delayed development of pupae and emergence of adults in the in-home environment.
• C. felis will orient and move up to 8.4 m towards a light source, although their jumping and collection in traps are greatly enhanced by a short interruption of the light, which may mimic host shadowing. C. felis prefer targets at 39°C over targets at 27°C. Other factors such as carbon dioxide and air currents stimulate jumping.

Detection

Monitoring infestations is an extremely important component of flea control. Visual assessment for indoor infestations has typically involved a "white-sock technique", in which a person wearing knee-high white socks walks in the room to be surveyed for 5 min and adult fleas that jump onto the socks are counted.

More advanced method is collecting fleas by a hand-held vacuum cleaner with a handkerchief inserted in the dust bag, which recovers 96% of adult fleas released in a room, compared with 77% recovered with the white-sock technique.

Commercially available traps with continuous light sources attract about 10% of adult fleas. A light trap with intermittent pulses of light attracts 57-86% of fleas.

In outdoor areas, a roller flea trap with a sticky adhesive surface catches 77% of the fleas released on a 0.8 m² grassy area.

Natural predators

Ants are known to be predators of all stages of fleas except the cocoon. There are reports of fleas preyed upon by some predatory species of Histerids (Clown beetles), Staphylinids (rove beetles), and Tenebrionid (darkening beetles). The parasitic nematode Steinernema carpocapsae will attack and kill larvae, pre-pupae, and pupae. However, fleas do not support complete nematode development, and moist substrates would be necessary for the nematode to survive to infect more than one generation of fleas. Currently, a product containing nematodes is registered for outdoor applications to turf and has been shown to be effective in reducing flea populations in soil.

Associated diseases

• Flea allergy dermatitis (FAD)

  The cat flea is primarily responsible for flea allergy dermatitis (FAD) in both dogs and cats. FAD is a hypersensitization to antigenic components contained in the saliva of fleas. Cats and dogs that have flea allergies will bite at the base of their tail and rump frequently. Animal become nervous and sleepless, sometimes, they vocalize (yelp or meow) sharply from a single flea bite. Even a few fleas can lead to prolonged itching that causes animal to groom extensively sometimes biting and scratching their skin, which can result in painful lesions.

• Dog tapeworm

  Cat fleas are the primary intermediate host of Dipylidium caninum (cucumber tapeworm or the double-pore tapeworm), the common intestinal cestode of dogs and cats that also rarely occurs in children after accidental ingestion of infected flea. Detailed life cycle of Dipylidium caninum

• Murine typhus

  Cat fleas are able to transmit murine typhus, also called flea-borne typhus or endemic typhus, a rickettsial disease caused by the organism Rickettsia typhi, which usually is associated with rat fleas (Xenopsylla cheopis).

• Flea-borne spotted fever

  Cat fleas are most common vectors of Rickettsia felis, relatively recently described pathogen, causative agent of flea-borne spotted fever (also called cat flea typhus). In 1994, the first human case of infection was reported in United States. Because the disease has similar clinical manifestation as murine typhus (including high fever, myalgia, and rash) and other febrile illnesses such as dengue, the infection in humans is likely underestimated.

• Cat scratch disease (CSD)

  Cat fleas have recently been implicated in the transmission of Bartonella henselae, the etiologic agent of cat scratch disease (CSD). In immunocompetent humans this infectious disease usually is not serious and associated with papule or blister at the site of injury (scratch or bite) and malaise. Cat scratch disease is a common cause of chronic lymph node swelling (lymphadenopathy) in children. It has been suggested that Bartonella spp. may be responsible for numerous chronic inflammatory conditions of the cat. It was shown that as many as 58% of stray cats can be Bartonella spp. carriers and up to 90% of fleas are infected. The prevalence of the infection is much lower in pet cats (~3%).

• Cat anemia

  Over 50% of cat fleas collected from stray cats were shown to be infected with Mycoplasma haemominutum or Mycoplasma haemofelis associated with infections in cats, which can range from subclinical and subtle anemia to severe hemolytic anemia.

• Plague

  Cat flea was shown to be a competent vector for transmission of plague (causative agent Yersinia pestis). Although not as efficient as rat fleas (Xenopsylla cheopis) C. felis is the most common flea in human habitations in many African countries and threat posed by the ectoparasite cannot be dismissed. Plague transmission is carried out by infected fleas that become "blocked" - a clot of microorganisms hinders flea's feeding forcing the flea to regurgitate overwhelming doses of the pathogen into the host and to seek the next available host.

Developmental stage

Life cycle of a flea from egg to egg-laying adult can be completed take as little as 18 days under optimal conditions (room temperature and humidity ~70%). Acquiring newly emerged fleas from an infested environment is more likely than from direct transfer of fleas from one host to another. Actual reproduction levels of fleas on a host will vary depending upon the level of grooming activity.

• egg Freshly laid egg is wet and sticks to the hairs of the host, however 60% of the eggs dry out and drop off within 2 h of deposition. The rate at which eggs are dislodged from the pelage depends on grooming activity, hair coat length, and host mobility.

  Rates of development

  The time required for eggs to hatch increases from 1.5 to 6.0 days as temperature decreases from 32 to 13°C.

  Viability

  About 70% of the eggs hatch when maintained at 16-27°C and 65 +- 5% relative humidity (RH). Exposure to low humidity (less than 33%) is lethal to egg; exposure to 3°C for more than 1 day kills most or even all eggs.
  
• larvae To develop normally larvae feed on adult flea feces that contain concentrated blood and other necessary nutrients. Therefore, visitations of refugia by infested hosts are important for larvae development. Also, cannibalistic consumption of unhatched eggs provides additional components for normal development of the larvae.

  Rates of development

  The rate of larval development is temperature and humidity dependent. At 13°C and 75% RH, about 50% of the larvae pupate within 34 days. Larval development requires 10 days at 50% RH and only 5 days at 95% RH if temperature is optimal. Females usually pupate ahead of males.

  Viability

  Larvae survive temperatures up to 27°C if the RH is more than 50%. Prolonged (for days) exposure to temperatures less than 10°C or brief exposures to 33% RH are lethal for most of the larvae. Consequently under unfavorable ambient conditions, larvae will only reach maturity in microhabitats such as under dense mats of ground cover or bushes and the base of carpets in the home.
  
• Pupa The late third instar voids its gut contents in preparation of forming a cocoon and pupation. The larva needs contact with a vertical surface to successfully spin a cocoon. The u-shaped larva begins pupal development about 18 h after completion of the cocoon. The silk fibers produced by the salivary glands are sticky, and debris from the environment adheres to the cocoon. Females emerge from the cocoon about 5–8 days after pupation and males emerge 7–10 days after pupation at 26.6°C. At lower temperatures, males consistently emerge later than females do.
  
• Pre-merged adult Adult flea in the cocoon. The flea can delay its emergence from the cocoon depending on the outside conditions. The cocoon serves as a barrier to emergence, helping to insure that a host is present when the adult flea emerges: mechanical pressure and heat stimulate emergence from the cocoon. At cool temperatures, fully formed fleas may remain in their cocoons for months.
  
• adult The majority of females mate with several males on the host within 34 h and lay eggs shortly after their first blood meal. C. felis can lay 40–50 eggs per day on immobilized host, and 85% of females and 58% of males remain on the host for at least 50 days.

  Viability

  The longevity of unfed adult females depends on temperature and relative humidity (RH). At 27°C in saturated air, about 90% of the females die within 11 days, a time period that decreases to 3.5 days at 50% RH. When hosts are declawed and prevented from grooming, an average of 85% of the female and 58% of the male fleas survive for at least 50 days, a few lasting for at least 113 days. Grooming accounts for about 50% mortality of adult fleas on the host in one week.

  Feeding habits

  Adults feed directly from capillaries. Female fleas can ingest an average of 13.6 μl of blood daily, about 15 times their body weight.

  Defecation

  Two types of fecal material are produced: spherules (unhydrolized blood) and coils (partially digested blood). Both have concentration of protein (5-7%). Flea larvae depend on access to adult feces for survival and it support the contention that a unique form of parental investment in larval nutrition may have evolved in Siphonaptera.
  

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Methods of control

Historically, cat fleas were controlled by chemical treatments of indoor and outdoor surfaces, which targeted not only pets' ectoparasites but also a broad range of other pests and could have been harmful for environment. The use of host-targeted therapies did not become popular until the registration of luferunon in 1995. Since then, a new paradigm of treating the pet rather than the environment flooded the market with various oral and topical treatments.

Chemical compound that interfere with the growth and development of arthropods are referred as insect growth regulators (IGRs). They can be subdivided further into juvenile-hormone analogs (JHAs) that prevent egg and larval stages from developing into adults and insect-developmental inhibitors (IDIs). IDIs interfere with many aspects of insect reproductive abilities and development and, currently, are used widely for tick, fly and flea control.

Product	Chemistry	Method of application	Stages affected	Efficiency	Mechanism
Selamectin	Avermectins and derivatives (a group of macrocyclic lactones produced by soil bacterium Streptomyces avermitilis and derivatives)	topical	all stages, especially larvae, and even eggs	>90%, residual protection for over 20 days	opening of chloride channels in muscle membranes of arthropods
Fipronil (Front-Line)	phenylpyrazole insecticide	spot-on topical	adult and off-host stages	>90%, residual protection for ~90 days	blocking (GABA)-gated chloride channels in central nervous system
Imidacloprid (Advantage)	chloronicotinyl insecticide	topical	adult and off-host stages	>90%, residual protection for ~20-40 days	competitive inhibiting at nicotinic acetylcholine receptors of the nervous system
Nitenpyram	chloronicotinyl insecticide (similar to imidacloprid)	orally	adults	within 8 hours, 100% of fleas are killed, remain active in the blood for 48 hours	competitive inhibiting at nicotinic acetylcholine receptors of the nervous system
Pyrethroids	similar to pyrethrins, natural compounds produced by the flowers of Chrysanthemum spp.	topical	adults	>90% in number of cat fleas for 28 days	opening sodium channels in the nervous system
Pyriproxyfen	IDI	topical	larval and eggs	significant reduction in flea numbers and almost 100% elimination over the period of six months	juvenile-hormone analog (JHA)
Lufenuron (Program)	IDI	orally or injections	larval and eggs	a 90% decrease in number of adult fleas emerging from eggs for ~200 days after treatment	insect-growth regulator (IGR), inhibits chitin synthesis
Methoprene	IDI	flea collar	larval and eggs	effective for 4 to 6 months on a dog and up to a year on cats	juvenile-hormone analog (JHA)

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Ctenocephalides felis female

Dantas-Torres F. Canine vector-borne diseases in Brazil. Parasit Vectors. 2008 Aug 8;1(1):25. PMID: 19645274

(a) Flea's head, exhibiting the characteristic genal (arrow) and pronotal (arrowhead) combs. (b) Spermatheca (arrow). (c) Chaetotaxy of tibia (arrow) of leg III.

Taxonomic keys of cat flea (University of São Paulo, Marcelo de Campos Pereira, PhD)

References

• Reif KE, Macaluso KR. Ecology of Rickettsia felis: a review. J Med Entomol. 2009 Jul;46(4):723-36. PMID: 19645274
• Wimsatt J, Biggins DE. A review of plague persistence with special emphasis on fleas. J Vector Borne Dis. 2009 Jun. PMID: 19502688
• Kamrani A et al. The prevalence of Bartonella, hemoplasma, and Rickettsia felis infections in domestic cats and in cat fleas in Ontario. Can J Vet Res. 2008 Oct;72(5):411-9. PMID: 19086373
• Pérez-Osorio CE, Zavala-Velázquez JE, Arias León JJ, Zavala-Castro JE. Rickettsia felis as emergent global threat for humans. Emerg Infect Dis. 2008 Jul. PMID: 18598619
• Haag KL, Gottstein B, Ayala FJ. Taeniid history, natural selection and antigenic diversity: evolutionary theory meets helminthology. Trends Parasitol. 2008 Feb. PMID: 18182327
• Prentice MB, Rahalison L. Plague. Lancet. 2007 Apr 7. PMID: 17416264
• Hawley JR, Shaw SE, Lappin MR. Prevalence of Rickettsia felis DNA in the blood of cats and their fleas in the United States. J Feline Med Surg. 2007 Jun;9(3):258-62. PMID: 17276123
• Sachse MM, Guldbakke KK, Khachemoune A. Tunga penetrans: a stowaway from around the world. J Eur Acad Dermatol Venereol. 2007 Jan. PMID: 17207161
• Parola P, Davoust B, Raoult D. Tick- and flea-borne rickettsial emerging zoonoses. Vet Res. 2005 May-Jun. PMID: 15845235
• Rust MK. Advances in the control of Ctenocephalides felis (cat flea) on cats and dogs. Trends Parasitol. 2005 May;21(5):232-6. PMID: 15837612
• Gage KL, Kosoy MY. Natural history of plague: perspectives from more than a century of research. Annu Rev Entomol. 2005;50:505-28. PMID: 15471529
• Rust MK, Dryden MW. The biology, ecology, and management of the cat flea. Annu Rev Entomol. 1997;42:451-73. PMID: 9017899
• Eisen RJ et al. Early-phase transmission of Yersinia pestis by cat fleas (Ctenocephalides felis) and their potential role as vectors in a plague-endemic region of Uganda. Annu Rev Entomol. 1997;42:451-73. PMID: 9017899
• Chomel BB et al. Ecological fitness and strategies of adaptation of Bartonella species to their hosts and vectors. Am J Trop Med Hyg. 2008 Jun PMID: 18541775
• Major topic "Fleas": free full-text articles in PubMed

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