General

Fleas represent one of the most important external parasites. At the moment there are more than 2,500 described species and subspecies throughout the world (Durden et al., 2005; Medvedev, 1998). 

Fleas are wingless insects with a laterally compressed body of about 1.5-4 mm length. Like all insects they possess six legs and three body segments.

Fleas have a history of about 60 million years and have been found on prehistoric mammals. While becoming parasitic, the original exterior of the two-wing insects, designating them to the order Diptera, has been changed as the wings in the adults were lost, whereas the larval form still has similarity with the larva of the order (Strenger, 1973).  

About 95% of the flea species parasitize on mammals, 5% live on birds. 

Taxonomy

Fleas are taxonomically grouped in the order Siphonaptera (Tenter and Schnieder, 2006), containing several families. The most important veterinary and human species belong to the families Pulicidae, including Pulex spp., Ctenocephalides spp., Spilopsyllus spp. and Archaeopsyllus spp., and Ceratophyllidae with the genera Ceratophyllus or Nosopsyllus.

 

Taxonomy of fleas of veterinary importance

Phylum:

Arthropoda

Class:

Insecta

Order:

Siphonaptera

Family: Pulicidae Ceratophyllidae
Genus: Ctenocephalides, Pulex,  
Spilopsyllus, Archaeopsyllus
 
etc. 
Ceratophyllus, Nosopsyllus etc. 
Species: Ctenocephalides felis  
(Bouché 1835) 
Ctenocephalides canis  
(Curtis 1826) 
Pulex irritans 
(Linné 1758) 
Spilopsyllus cuniculi  
(Dale 1878) 
Archaeopsyllus erinacei  
(Bouché 1835) 
Ceratophyllus gallinae  
(Schrank 1804) 
Ceratophyllus columbae  
(Stephens 1829) 

Distribution

The most important flea species of companion animals, the cat flea Ctenocephalides felis was probably introduced only quite recently into Europe when domestic cats were imported at the time of the Crusades (Petter, 1973; Beaucournu, 1990).

Believed to originate from Africa, the so-called ‘cat flea’ C. felis is now cosmopolitan, ranging from warm tropical areas to temperate zones with prolonged subfreezing temperatures (Lewis, 1972). Regarding the different suspected subspecies of C. felis, newer data confirm three subspecies: the cosmopolitan C. felis felis, C. f. strongylus in Africa and the Arabian Peninsula, and C. f. damarensis in South Africa. Furthermore, the full species status of C. orientis, C. canis and C. connatus is confirmed (Lawrence et al., 2019).

C. felis is found worldwide on many species of wild and domesticated animals (Rust and Dryden, 1997). C. canis is more prevalent on dogs in some countries such as Greece, Iran, and Turkey (Rust, 2017). Detailed data on the worldwide distribution can be found in Rust (2017). 

Epidemiology

The flea's biology makes it a very efficacious vector of many pathogens (Genchi, 1992). Only about 5% of the flea population lives and feeds on the animals, the remaining 95% (eggs, larvae and pupae) are spread around the host animals’ habitat.  

While the prevalence of Ctenocephalides felis is seasonal, it still appears throughout the year (Rust, 2017). In buffered microclimate situations such as buildings in towns, cat flea populations develop year round. This can result in unexpected large peak outbreaks caused by the sudden emergence of a very large number of individuals, when habitations abandoned by domestic animals and their owners for longer or shorter times are reinhabited (Genchi, 1992). 

The reasons that the cat flea is such an extremely successful and ubiquitous parasite are the wide range of possible hosts and its status as a rather permanent parasite (Dryden, 1993; Grant, 1996).  

Since all life cycle stages of C. felis are susceptible to desiccation, only those eggs that fall into protected microhabitats hatch larvae that will ultimately develop into adults (Dryden, 1989). 

 

Areas that may be suitable for flea development in the house are (Dryden, 1989): 
  • pet’s bedding 
  • thick shag carpet 
  • carpeted or dirt floor basements 

 

Potentially favourable developmental sites outside occur where there is moist soil and shade: 
  • dog houses 
  • flower beds 
  • areas under bushes 
  • damp crawl spaces 
  • gardens 
  • any places where the flea-infested animal might rest during the heat of the day 

 

Summarising, significantly more fleas are found in rooms where pets spend most of their time resting (Osbrink et al., 1986). 

The abundance of adult cat fleas fluctuates with seasonal changes. The warm months of spring and summer give rise to the highest numbers, whereas few are found during the cold months of late fall and winter (Metzger and Rust, 1997). The main strategies hypothesized for overwintering of the cat flea are reinfestation from feral mammals and preemerged adults inside cocoons emerging only when conditions are favourable for further development.

 
The survival and maintenance mechanisms of C. felis, important for epidemiological considerations, can be summarised as follows (Rust and Dryden, 1997):  
  1. The presence of adults on domestic and feral cats and dogs. 
  2. The presence of adults on urbanised small wild mammals. 
  3. A delayed development of immature stages in freeze-protected underground dens of wildlife. 
  4. A delayed development of pupae and emergence of adults in the home environment. 

References

Introduction

Durden LA, Judy TN, Martin JE, Spedding LS: Fleas parasitizing domestic dogs in Georgia, USA: species composition and seasonal abundance. Vet Parasitol. 2005, 130, 157-62

Medvedev SG: Classification of fleas (Order Siphonaptera) and its theoretical foundations. Entomol Rev. 1998, 78, 1080-93

Strenger A: [About the nutritional physiology of the larva of Ctenocephalides felis felis.] B Zool Jahrb Syst Bd. 1973, 100, 64-80 [in German]

 

Taxonomy

Tenter A, Schnieder T: [Pathogens of parasitic diseases: Taxonomy, systematics and general criteria.] In: Schnieder T (ed.): Veterinärmedizinische Parasitologie. 6th edn., 2006, Parey in MVS, Stuttgart, pp 26-73 [in German]

 

Distribution

Beaucournu JC: Les puces synanthropes. Bull Soc Franç Parasitol. 1990, 8, 145-56 

Lawrence AL, Webb CE, Clark NJ, et al.: Out-of-Africa, human-mediated dispersal of the common cat flea, Ctenocephalides felis: The hitchhiker's guide to world domination. Int J Parasitol. 2019, 49, 321-36

Lewis RE: Notes on the geographic distribution and host preferences in the order Siphonaptera. Part 1. Pulicidae. J Med Entomol. 1972, 9, 511-20 

Petter F: Les animaux domestiques et leurs ancêtres. 1973, Bordas Edition, Paris 

Rust MK: The biology and ecology of cat fleas and advancements in their pest management: a review. Insects. 2017, 8, 118 

Rust MK, Dryden MW: The biology, ecology, and management of the cat flea. Ann Rev Entomol. 1997, 42, 451-73 

 

Epidemiology

Dryden MW: Biology of the cat flea, Ctenocephalides felis felis. Comp Anim Pract. 1989, 19, 23-7 

Dryden MW: Biology of fleas of dogs and cats. Comp Cont Educ Pract Vet. 1993, 15, 569-79 

Genchi C: Arthropoda as zoonoses and their implications. Vet Parasitol. 1992, 44, 21-33 

Grant D: Flea biology and control. Vet Pract. 1996, 28, 7-8 

Metzger ME, Rust MK: Effect of temperature on cat flea (Siphonaptera: Pulicidae) development and overwintering. J Med Entomol. 1997, 34, 173-8 

Osbrink WLA, Rust MK, Reierson DA: Distribution and control of cat fleas in houses in Southern California (Siphonaptera: Pulicidae). J Econ Entomol. 1986, 79, 135-40 

Rust MK: The biology and ecology of cat fleas and advancements in their pest management: a review. Insects. 2017, 8, 118 

Rust MK, Dryden MW: The biology, ecology, and management of the cat flea. Ann Rev Entomol. 1997, 42, 451-73 

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