Fleas Of Medicalveterinary Importance

Human flea (Pulex irritans) This flea will feed on humans and is capable of transmitting pathogens of medical importance. However, it is more commonly an ectoparasite of swine and domestic cats and dogs in most parts of the world. Although P. irritans is currently an infrequent parasite of humans in developed countries, this has not always been the case. P. irritans has a patchy but cosmopolitan distribution and often occurs in remote and isolated areas. Adults of this species lack both genal and pronotal ctenidia (Fig. 7.2C). P. simulans is a closely related species that parasitizes large mammals, including wild canids and domestic dogs, and sometimes people, in the New World. Older records (before 1958) from this region are unreliable and could refer to either P. irritans or P. simulans.

Cat flea (Ctenocephalides felis)

The cat flea occurs worldwide and is currently the most important flea pest of humans and many domestic animals. It is primarily a nuisance because it feeds not only on domestic and feral cats, but also on humans, domestic dogs, and several livestock species. It also parasitizes wild mammals such as opossums and raccoons. This ectoparasite is the most common flea on dogs and cats in most parts of the world. Some strains of the cat flea appear to have adapted to hosts such as horses or goats. Cases of severe anemia associated with huge numbers of cat flea bites have been recorded for these and other domestic animals.

Female cat fleas in most populations produce larger numbers of fertile eggs if they take their blood meals from cats rather than other host species. Under optimal conditions a female cat flea can lay about 25 eggs per day for a month, contributing to very high densities of fleas in a relatively short time. Adult cat fleas have well-developed genal and pronotal ctenidia (Figs. 7.2A and 7.3) and can be distinguished from the dog flea (C. canis) by the longer head and longer first spine in the genal comb in C. felis. For further details on the biology of the cat flea, see Dryden (1993) and Rust and Dryden (1997).

Dog flea (Ctenocephalides canis)

This flea (Fig. 7.2B) is much less common on domestic dogs in most parts of the world than it was in previous decades. Instead, the cat flea has become the most common flea on domestic dogs. No satisfactory explanation for this change has been documented; perhaps cat fleas can outcompete dog fleas under stress from modern pesticide applications. Nevertheless, dog fleas persist worldwide and remain as the predominant fleas on dogs in Ireland, Israel, and a few other countries. Dog fleas also parasitize wild canids such as foxes, coyotes, and wolves, on which they can be relatively common.

Oriental rat flea (Xenopsylla cheopis)

This flea is the principal vector of the agents of plague and murine typhus throughout many of the tropical and subtropical parts of the world. Some other species of Xenopsylla also are vectors of the plague bacillus. Although it is most common on domestic rats, it also will readily feed on humans, dogs, cats, chickens, and other hosts especially if rats become scarce. Like the human flea, adults of X. cheopis lack both a pronotal and a genal ctenidium (Fig. 7.2F).

European rabbit flea (Spilopsyllus cuniculi)

Originally from Europe, this flea has accompanied its host the European rabbit as it has been introduced throughout the world, either inadvertently or as a laboratory animal. It is an example of a sedentary or stick-tight flea; adults attach to the host for long periods using their elongate mouthparts to anchor them in host skin and to feed. This flea typically attaches to the ears of rabbits, where a rich peripheral blood supply provides easily accessible blood meals. Adults have a genal ctenidium with a row of five blunt spines oriented almost vertically on the head and a well-developed pronotal ctenidium.

Sticktight flea (Echidnophaga gallinacea) As indicated by its name, this is another sticktight flea. It is distributed globally wherever chickens have been introduced as domestic animals. This flea usually attaches semipermanently around the head, especially on the wattle, of chickens (Fig. 7.11). Many additional hosts are also parasitized by E. gallinacea, including other domestic birds (e.g., turkeys, quail), domestic rats, dogs, cats, and occasionally humans. Adults of this small flea are easily recognized by their sharply angled squarish head and the absence of both pronotal and genal ctenidia.

Chigoe (Tunga penetrans)

This flea, also called the jigger or sand flea, has major medical and veterinary significance because it burrows into the tissues of humans and some domestic

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