Unusual Cause Of Persistent Intense Itching And Dermatitis

Gamasoidosis (acariasis, avian-mite dermatitis or bird-mite dermatitis) is a challenging diagnosis that is becoming more common because of the frequent use of window air conditioners which serve as shelters for bird nests. Bird mite bites are one of many zoonotic causes of persistent itching, which is rarely diagnosed accurately by the general physicians. Extreme conditions can lead to severe psychological discomfort, especially in elderly and children who spend most of their time indoors. The itch is particularly intense at resting time. In some affected individuals, a rash, which can be made up of papules may develop, a condition called gamasoidosis.

Bird mites are barely visible to naked eye and move quite fast on skin. They are transparent and difficult to notice, but once they ingest blood, which gives them color upon digestion, they get easily noticeable. These mites feed preferentially on unfeathered nestlings. Up to 50,000 mites can be found in a nest. Although the mites stay on birds at night, during the night they may move on to humans. When the birds leave their nests or die, thousands of starving mites may wander into homes or offices through windows or attics and begin biting people. The bites are sharp and painful and may develop into substantial wheals. Scratching further inflames the bites and easily leads to secondary infection.

Bird-mite dermatitis
Bird-mite dermatitis Source: CDC

Ornithonyssus bursa, or tropical fowl mite, is a common parasite of sparrows, pigeons and many native song birds and the most common bird mite that attacks humans. This mite species is a vector of the pathogens of fowlpox (a slow-spreading viral infection of chickens and turkeys ), Newcastle disease (may cause cause mild conjunctivitis and influenza-like symptoms in humans) and Pasteurella bacteria (causes soft-tissue inflammation that may resemble group A β-hemolytic Streptococcus pyogenes infections). Infestations with tropical fowl mite are very hard to treat because unlike its close relatives Ornithonyssus sylviarum (northern fowl mite) and Dermanyssus gallinae (poultry red mite), it lays eggs away from its host.

Dermanyssus gallinae infestations cause skin rashes over forearm, chest and back of neck. Blistering rash is covered with bloody crust due to violent itching. The mites may also afflict the skin causing intensified itching on the backs of the hands and forearms, scalp (causing scalp itching), face, pubic hairs, external ears (causing otitis externa), nares, orbits and eyelids, and genitourinary and rectal orifices.4

Mite-induced dermatitis
>Dermanyssus gallinae dermatitis Source: Journal of Arthropod Borne Diseases


  1. Intractable Pruritus Caused by Pigeon Mites. Vivek Chauhan et al.
  2. Veterinary Ectoparasites: Biology, Pathology and Control. R. L. Wall, David Shearer
  3. Biology of Disease Vectors. William H. Marquardt (editor)
  4. Human Infestation with Dermanyssus gallinae (Acari: Dermanyssidae) in a Family Referred with Pruritus and Skin Lesions Mohammad Abdigoudarzi,1,* Mahmoud S Mirafzali,2 and Hamid Belgheiszadeh3 J Arthropod Borne Disv.8(1); 2014

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