Fleas as parasites of the family Canidae

Fleas (Order Siphonaptera) form a unique group of insects. They have evolved in the early Cretaceous or Jurassic ages between 125 to 150 million years ago, probably together with the evolution of marsupials and insectivors. Historically, fleas are among the most important ectoparasites of humans in that several species are the natural vectors of several important infectious diseases, like plague. Today, some 15 families with a total of about 220 genera and some 2,500 species of fleas can be distinguished [1].Out of these, five families and 25 genera are ectoparasites of birds, and all other fleas parasitize mammals. Most fleas of veterinary importance are grouped in the families Pulicidae, Ceratophyllidae, Leptopsyllidae and Vermipsyllidae. Rarely, members of other families (Hystrichopsyllidae, Rhopalopsyllidae) may be found on domestic animals. Besides domestic cats, dogs may play a peculiar role as bridging hosts for fleas of different wild animals, domestic animals and humans, as they will come into contact with different animals during their seeking behaviour and therefore acquire the fleas of different animals. Fleas may play different roles as parasites in mammals. They may act as vectors to transmit pathogens. They may play a role as intermediate hosts of parasites and can be an ectoparasitic nuisance in animals and humans which may cause allergic reactions.Fleas are wingless, 1-8 mm in size with laterally compressed bodies composed of a blunt head, a compact thorax and a fairly large, rounded abdomen. The colour is usually dark brown. Small eyes may or may not be present. The bodies of adult fleas bear many spines which are used for species determination. Among them are the combs or ctenidia, a row of enlarged sclerotized spines on the head (genal ctenidium), which are always absent in fleas parasitizing birds, or on the prothorax (pronotal ctenidium) which may be present or absent.Fleas develop from eggs to larvae (usually consisting of three instar generat