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Anais Brasileiros de Dermatologia

Print version ISSN 0365-0596

An. Bras. Dermatol. vol.87 no.6 Rio de Janeiro Nov./Dec. 2012 



Gamasoidosis illustrated - from the nest to dermoscopy*


Gamasoidose ilustrada - do ninho à dermatoscopia



Carlos Gustavo WambierI; Sarah Perillo de Farias WambierII

IM.D., Ph.D.; Dermatologist - Division of Dermatology, School of Medicine of Ribeirão Preto - University of São Paulo (FMRP-USP) - São Paulo (SP), Brazil
IIM.D.; Ophthalmologist and Oculoplastic Surgeon - PhD Student - School of Medicine of Ribeirão Preto - University of São Paulo (FMRP-USP) - São Paulo (SP), Brazil

Mailing address




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.

Keywords: Ectoparasitic infestations; Mite infestations; Mites


Gamasoidose (acaríase, infestação por "piolhinho-de-pombo" ou dermatite por ácaros aviários) é um diagnóstico desafiador que está se tornando mais comum devido ao uso frequente de aparelhos de ar-condicionado de janela em países tropicais, que servem de abrigo para ninhos de pássaros urbanos tais como pombos. Dermatologistas devem se familiarizar com esta infestação para fazerem diagnóstico e tratamento adequados.

Palavras-chave: Ácaros; Ectoparasitoses; Infestações por ácaros



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.



1. Kowalska M, Kupis B. Gamasoidosis (gamasidiosis)-not infrequent skin reactions, frequently unrecognized. Pol Med Sci Hist Bull. 1976;15-16:391-4.         [ Links ]

2. Orton DI, Warren LJ, Wilkinson JD. Avian mite dermatitis. Clin Exp Dermatol. 2000;25:129-31.         [ Links ]

3. Lucky AW, Sayers C, Argus JD, Lucky A. Avian mite bites acquired from a new source--pet gerbils: report of 2 cases and review of the literature. Arch Dermatol. 2001;137:167-70.         [ Links ]

4. Regan AM, Metersky ML, Craven DE. Nosocomial dermatitis and pruritus caused by pigeon mite infestation. Arch Intern Med. 1987;147:2185-7.         [ Links ]

5. Bellanger AP, Bories C, Foulet F, Bretagne S, Botterel F. Nosocomial dermatitis caused by Dermanyssus gallinae. Infect Control Hosp Epidemiol. 2008;29:282-3.         [ Links ]

6. Schulze KE, Cohen PR. Dove-associated gamasoidosis: a case of avian mite dermatitis. J Am Acad Dermatol. 1994;30:278-80.         [ Links ]

7. Ribeiro VLS, Moojen V, Telles APD. Ornithonyssus bursa: parasito de aves causando acaríases cutâneas em humanos no Rio Grande do Sul, Brasil. An Bras Dermatol. 1992;67:31-4.         [ Links ]



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, 4th floor
Av. Bandeirantes 3900
14049-900 Ribeirao Preto, SP

Received on 27.07.2011.
Approved by the Advisory Board and accepted for publication on 26.12.2011.
Conflict of interest: None
Financial funding: None



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

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