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Gamasoidosis illustrated: from the nest to dermoscopy.
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PMID:  23197219     Owner:  NLM     Status:  In-Data-Review    
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 in tropical countries. These devices may serve as shelters for nests of urban birds such as pigeons. Dermatologists should become familiar with this infestation to establish the correct diagnosis and treatment.
Carlos Gustavo Wambier; Sarah Perillo de Farias Wambier
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Anais brasileiros de dermatologia     Volume:  87     ISSN:  1806-4841     ISO Abbreviation:  An Bras Dermatol     Publication Date:  2012 Dec 
Date Detail:
Created Date:  2012-11-30     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0067662     Medline TA:  An Bras Dermatol     Country:  Brazil    
Other Details:
Languages:  eng     Pagination:  926-7     Citation Subset:  IM    
Division of Dermatology, School of Medicine of Ribeirão Preto, University of São Paulo, São Paulo, SP, Brazil.
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Journal Information
Journal ID (nlm-ta): An Bras Dermatol
Journal ID (iso-abbrev): An Bras Dermatol
Journal ID (publisher-id): An. bras. dermatol.
ISSN: 0365-0596
ISSN: 1806-4841
Publisher: Sociedade Brasileira de Dermatologia
Article Information
Download PDF©2012 by Anais Brasileiros de Dermatologia
Received Day: 27 Month: 7 Year: 2011
Accepted Day: 26 Month: 12 Year: 2011
Print publication date: Season: Nov-Dec Year: 2012
Volume: 87 Issue: 6
First Page: 926 Last Page: 927
PubMed Id: 23197219
ID: 3699918
DOI: 10.1590/S0365-05962012000600021

Gamasoidosis illustrated - from the nest to dermoscopy*
Carlos Gustavo Wambier1
Sarah Perillo de Farias Wambier2
1M.D., Ph.D.; Dermatologist - Division of Dermatology, School of Medicine of Ribeirão Preto - University of São Paulo (FMRP-USP) - São Paulo (SP), Brazil
2M.D.; Ophthalmologist and Oculoplastic Surgeon - PhD Student - School of Medicine of Ribeirão Preto - University of São Paulo (FMRP-USP) - São Paulo (SP), Brazil
Correspondence: Mailing address: Carlos G. Wambier, MD, Division of Dermatology, Department of Internal Medicine, School of Medicine of Ribeirao Preto - University of Sao Paulo - Hospital of Clinics FMRPUSP, Av. Bandeirantes 3900, 4th floor, 14049-900 Ribeirao Preto, SP, E-mail:

Gamasoidosis (acariasis, avian-mite dermatitis or bird-mite dermatitis) is a frequently unrecognized ectoparasitosis. 1-6 In contrast to scabies, mites spare interdigital spaces, axillae, and genitalia and cannot be found in human skin because they leave the host after feeding. 2 Nosocomial infestations have been reported. 4,5 Urban gamasoidosis is becoming common in tropical countries because of the frequent use of window air conditioners, which serve as shelters for bird nests.

These photos illustrate gamasoidosis in an apartment where two people lived. Patients presented with unexplained chronic pruritus in the neck and shoulders for 3 months, with occasional signs of dermographism and excoriations (Figure 1). The symptoms were relieved with antihistamines, as initial diagnosis was an urticarial reaction.

A specimen was taken to the dermatologist's office by one patient immediately after he found an unrecognizable "dot" when searching his neck after a "crawling" sensation. Dermoscopy revealed an avian mite, further identified as Ornithonyssus bursa (Figure 2). 7 The bedroom window air conditioner was found to be the source of hundreds of these mites (Figure 3). After the removal of the device, a pigeon nest was found (Figure 4). Symptoms resolved after the air conditioner was cleaned and a chain-link fence was put into place to prevent future nesting.

Gamasoidosis is a challenging diagnosis. This infestation can be caused by various mites, such as: Ornithonyssus sylviarum (northern fowl mite), Ornithonyssus bursa (tropical fowl mite), Dermanyssus gallinae (red mite), and Dermanyssus avium. Dermoscopic identification criteria to differentiate mites are still to be described. Dermoscopy may assist in ruling out the diagnosis of parasitosis delirium.


Conflict of interest: None

Financial funding: None

fn01* Work conducted at the School of Medicine of Ribeirão Preto - University of São Paulo (FMRP-USP) - Ribeirão Preto (SP), Brazil.

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4. Regan AM,Metersky ML,Craven DE. Nosocomial dermatitis and pruritus caused by pigeon mite infestationArch Intern MedYear: 1987147218521873689070
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[Figure ID: f01]

Gamasoidosis. Occasional urticarial plaques (black arrow tips). Arrow illustrates excoriated papule

[Figure ID: f02]

Dermoscopy of an avian mite. Dermoscopy (10x) of an avian mite measuring 1 mm in the surface of the fingertip

[Figure ID: f03]

Panel C. March of the avian mites. Avian mites crawled from the air-conditioning window unit to the wall at night to feed. The black arrow tips illustrate how difficult it is to notice the 1 mm mites. White background accentuates contrast. In a dark background, they become virtually invisible to the naked eye

[Figure ID: f04]

Panel D. Empty pigeon nest inside the air-conditioning unit. An empty nest full of avian mites was found inside the air-conditioning unit

Article Categories:
  • Imaging In Tropical Dermatology

Keywords: Ectoparasitic infestations, Mite infestations, Mites.

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