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Bites from ticks that cause dermatitis
Last reviewed: 07.07.2025
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There are many species of biting mites. Trombicula irritans is probably the most common. The larvae of this species are found everywhere in nature except in dry areas. They bite, feed in the skin, and then fall off. Outside the United States, Trombicula irritans can be a vector for Rickettsia tsutsugamushi. They do not burrow into the skin, but their small size makes them difficult to detect on the skin surface.
Among the mites that burrow into the skin after a bite are often Sarcoptes scabiei (the causative agent of scabies) and Demodex mites. Demodex mites cause a scabies-like dermatitis (sometimes confused with scabies), which is almost exclusively found in animals, and possibly acne.
Dermatitis is caused by mites that bite people accidentally, being in most cases ectoparasites of birds, rodents or domestic animals; and mites associated with plants, food supplies. Bird mites may bite people who come into contact with live birds or people whose houses have nesting birds. Mites from rodents, cats, dogs (especially puppies), rabbits and swine mange mites (S. scabiei var suis) on pig farms or in domestic pigs may also bite people.
The straw mite (Puemo tes tritici) is often associated with seeds, straw, hay, or other plant material; it parasitizes soft-bodied insects that live (or lived) in such plant material. These mites often bite people who come into their habitats. These may include grain storage workers who come into contact with grass seeds or hay, and those who dry plants. These people are at the highest risk of being bitten.
Several species of mites associated with stored grain, cheese, and other foods do not bite but cause allergic dermatitis or "grocer's itch" because people become sensitized to allergens on the mites themselves or in their excrements.
House dust mites do not bite, but feed on dead skin cells in pillows, mattresses, and floors (especially carpets). They have a significant impact on human health because many people develop pulmonary hypersensitivity to allergens found in the mites' outer shell and feces.
[ Symptoms of tick bites causing dermatitis
Most bites cause a pruritic dermatitis-like rash; the itch from Trombicula irritans bites is particularly intense. Non-invasive tick bites are diagnosed by history (eg, residence, occupation, and environment) and physical examination. Ticks themselves are rarely found because they fall off after feeding (the skin reaction is usually delayed, and most patients do not seek medical attention until several days have passed). Lesions caused by ticks are usually indistinguishable and resemble other skin conditions (eg, other insect bites, contact dermatitis, folliculitis). Skin biopsy can be used to diagnose non-invasive tick bites.
Treatment of tick bites causing dermatitis
Treatment of non-invasive mite bites is symptomatic; topical glucocorticoids or oral antihistamines are used as needed to relieve itching until the hypersensitivity reaction resolves. After discussing possible sources, the physician can help the patient avoid recurrence of mites. Treatment of Demodex bites is done in conjunction with veterinary consultation. For treatment of scabies, respiratory hypersensitivity, and other systemic allergic reactions, see the appropriate sections.