Merck Manual

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Professional Version

Sand Flies of Animals

By

Jan Šlapeta

, MVDr, PhD, GradCertEd (Higher Ed), Sydney School of Veterinary Science, The University of Sydney

Medically Reviewed Aug 2022 | Modified Oct 2022

The phlebotomine sand flies, Phlebotomus spp (Old World sand flies) and Lutzomyia spp (New World sand flies), are members of the family Psychodidae. These flies are confined primarily to the tropical and subtropical regions of the world. Members of these genera are tiny, moth-like flies, ~1.5–4 mm long. The legs are as long as the antennae, comprising 16 segments that often have a beaded, hairy appearance. They are commonly known as sand flies, moth flies, or owl midges. The key morphologic feature for identification is that the body of the sand fly is covered with fine hairs. The females have piercing mouthparts and feed on blood of a variety of warm-blooded animals, including humans. Many species feed on reptiles. Male sand flies suck moisture from any available source and are even said to suck perspiration from humans.

Sand flies tend to be active only at night and are weak fliers; their flying is deterred by air currents, even slight ones. During the day, sand flies seek protection in crevices and caves, stone walls, among vegetation, and within dark buildings. They often seek protection within rodent and armadillo burrows; these mammals can serve as reservoir hosts for Leishmania spp. Sand flies breed in dark, humid environments that have a supply of organic matter that serves as food for the larvae. They do not breed in aquatic environments.

Pathology of Sand Flies of Animals

These tiny flies serve as an intermediate host for Leishmania spp Leishmaniosis , a protozoan parasite that infects the reticuloendothelial cells of capillaries, the spleen, and other organs but may be seen in monocytes, polymorphonuclear leukocytes, and macrophages of humans, dogs, cats, horses, and sheep.

Diagnosis of Sand Flies of Animals

Like black flies, sand flies can most often be collected in the field and are not found on animals. They can be identified by their small size and hairy wings and bodies. Identification of genus and species is best left to an entomologist.

Treatment and Control of Sand Flies of Animals

  • Control of sand flies requires systematic destruction of their habitat and indoor spraying of insecticides that have residual activity

  • Deltamethrin-impregnated dog collars on dogs protect both humans and dogs from sand flies and leishmaniasis

Insecticide spraying of larval habitat is usually not possible because of the difficulty of accessing breeding sites. Removal of dense vegetation discourages breeding. Spraying of residual insecticides on surfaces in the home is the main way to control sand flies; however, this is ineffective for species that bite away from the home. In general, populations of sand flies have been reduced as a result of intense mosquito control programs. In situations where dogs are the preferred blood source for sand flies and thus reservoir of Leishmania, the presence of deltamethrin-impregnated dog collars on dogs helps to decrease sandfly population. Deltamethrin-impregnated collars or permethrin-fipronil products may be recommended to dog owners to protect their pets from sand fly bites. Economically and environmentally sustainable approaches to decrease sand fly populations are urgently needed to decrease the spread of Leishmania spp.

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