Ticks are the most competent and versatile of all arthropod vectors of zoonotic infectious diseases for several reasons. First, ticks are not afflicted by most of the microorganisms that they may transmit or the paralytic salivary toxins that they may…
Mites, including chigger and scabies mites, are among the smallest arthropods, with most barely visible without magnification. Only about 20 species of the more than 3000 species of chigger, animal, plant, and scabies mites are of any medical importance, and…
Flies and fleas are mostly bothersome biting nuisances of humans and animals that can also transmit infectious diseases and deeply invade living tissues, causing amputation, disfigurement, and, rarely, death. Flies can serve as mechanical vectors of shigellosis, and rat fleas…
Scabies, an infection by the itch or scabies mite, Sarcoptes scabiei var. hominis, remains a major public health problem throughout the developing world ( Fig. 293.1 ). Scabies in its most severe form, crusted or Norwegian scabies ( Fig. 293.2…
Pediculosis is a complex of three different human infestations with two species of blood-sucking lice of the insect order Phthiraptera, suborder Anoplura: Pediculus humanus and Phthirus pubis. Sometime after early humans began to wear clothes, P. humanus evolved into two…
Ectoparasites infest the skin and its appendages, such as the hair and sebaceous glands, and most external orifices, especially the ears, nares, and orbits. Like endoparasites, ectoparasites may be obligatory parasites, programmed to feed on human hosts to complete their…