- Pulex, Xenopsylla, and Ctenocephalides (Human, Rat, and Dog/Cat Fleas)

Fleas are small, wingless insects (1-10 mm in length) whose 2500 or so recognized species/subspecies are placed in the order Siphonoptera (consisting of 16 families). Fleas are characterized by having a laterally compressed body (allowing rapid movement among hair or feathers), well-developed mouthparts (for piercing host skin and sucking blood), enlarged hind legs (adapted for jumping), strong tarsal claws (adapted for holding onto their hosts), backward pointing hairs and bristles (for ease of movement through the hair of a host), and small antennae (tucking away into special groves in the head). Being hematophagous ectoparasites, ›eas do not cause signi‘cant damage to their hosts, and are generally considered as a nuisance. However, due to their potential roles in the transmission of other important microbial pathogens, ›ea infestations demand adequate attention, including correct identi‘cation and prompt treatment, to protect the well-being of humans and animals. With medically important ›eas being mainly in the genera Pulex, Xenopsylla, Ctenocephalides, and Tunga, this chapter is devoted to the genera of Pulex, Xenopsylla, and Ctenocephalides, while Chapter 82 of this book focuses on the genus Tunga.