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
|Ceratophyllus, Nosopsyllus etc.|
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).
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
- 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):
- The presence of adults on domestic and feral cats and dogs.
- The presence of adults on urbanised small wild mammals.
- A delayed development of immature stages in freeze-protected underground dens of wildlife.
- A delayed development of pupae and emergence of adults in the home environment.
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