Ectoparasites: Myiasis, Tungiasis, Scabies

Ectoparasites are arthropods living on the outside of the host from which they obtain their nutrients. Some of them have direct intrinsic cutaneous effects on their human hosts. Very few are commonly found in travelers. The three most frequent ectoparasitic skin infections of travelers are cutaneous myiasis and tungiasis, which are geographically related, and scabies, which is cosmopoplitan. Myiasis is an infestation of human tissue by larvae of some types of fly. Among travelers to Latin America, Dermatobia hominis (botfly) is the most common form, whereas in travelers to Africa Cordylobia anthropophaga (tumbu fly) is the most common. Tungiasis is caused by Tunga penetrans, which is a small flea. It is seen in travelers returning from Latin America (largely Brazil) and Sub-Saharan Africa. Scabies, infestation by Sarcoptes scabei, is the most common cause of diffuse pruritic skin disease in travelers. Treatment for both myiasis and tungiasis is removal of the parasite. Treatment for scabies relies on topical agents (permethrin cream, lindane, benzyl benzoate) or oral ivermectin.