Gamasidosis is a dermatitis caused by gamasid mites. Gamasidosis caused by rite mites is also known as rite mite itch, while gamasidosis caused by bird mites is also known as gamasoidosis, avian mite dermatitis, or bird mite dermatitis.


Gamasid mites are oval or elliptical, 0.2 - 0.5mm long, with keratinized yellow or brown bone plates.

Most gamasid mites live on their own and few are parasites. Most non-parasitic gamasid mites live in the deadwoods, decaying leaves, grass, soil, manure, and warehouse products, and parasitic gamasid mites predominantly live on the surface of the host, rarely in the body, such as the nasal cavity, respiratory tract, external auditory canal, and lungs.

Figure 1 gamasid mite

Signs and Symptoms

The skin lesions are usually multiple, independent, red itchy papules, wheals, and papulovesicles, often with a pinhead sized petechia on the center, with severe pruritus. The skin lesions are clustered or linear, mostly on the calves, ankles, and belt area. There may be scratch marks, blood scabs, or infected scabs caused by secondary infections.

Figure 2 gamasidosis

In addition to dermatitis, gamasid mites can also transmit murine typhus, encephalitis, epidemic hemorrhagic fever, rickettsial pox, and tularemia.


If there is a history of exposure to birds or animals, clinical manifestations, particularly severe pruritus, the disease can be considered.


Topical 5% sulfur cream or 1% phenol calamine lotion is appropriate. Antihistamines are given to patients with severe symptoms. If there are systemic symptoms, in addition to symptomatic treatment, chloramphenicol or tetracycline should be administered promptly.