Introduction to Ectoparasitic Diseases

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 life cycles, or facultative parasites, preferring to feed on nonhuman hosts, infesting humans only as accidental or dead-end hosts. Over the past 2 decades, there have been several reports of significant outbreaks of ectoparasitic diseases, principally myiasis, scabies, and tungiasis, both in indigenous populations and in travelers returning from developing nations and even exclusive tropical beach resorts. Many common ectoparasites, such as head lice and scabies mites, are also developing increasing resistance to medical therapies, including the safest topical insecticides. Other ectoparasites, such as the New World human botfly, Dermatobia hominis, and the jigger or chigoe flea, Tunga penetrans, are resistant to systemic and topical antiparasitics and can be treated only surgically.

Ectoparasitic diseases have reemerged as unusual, but not uncommon, infectious diseases worldwide, especially in high-risk populations. Indigenous populations of ectoparasite-endemic tropical nations often have recurrent infestations and superinfestations that can result in severe disfigurement from facial cavitary myiasis or permanent disability from tungiasis-associated autoamputations.