Allergic contact dermatites caused by Dermatophagoides pteronyssinus in humans in Southern Brazil

Mites of the genus Dermatophagoides are significant and common triggers of allergies in humans, often found in household dust. Despite not being hematophagous, they possess medical and veterinary relevance due to their involvement in the etiology of allergic diseases such as asthma, rhinitis, conjunctivitis, and atopic dermatitis. Studies have been conducted worldwide to determine dust mite species, types and levels of allergens, and their association with various allergic conditions. However, in Brazil, research has mainly focused on identifying allergens associated with respiratory allergies. Specifically, in Rio Grande do Sul, studies in this area are limited. Therefore, we report here the identification of D. pteronyssinus as a cause of allergic contact dermatitis in humans in the state. In this report, two patients residing in the Southern region of Rio Grande do Sul, Brazil, sought assistance after experiencing intense itching and swollen red lesions on their bodies, particularly on the back, legs, and arms, coincidentally following the acquisition of a new sofa. Pieces of transparent adhesive tape were repeatedly applied to the recently purchased sofa. The tapes were attached to slides and examined under light microscopy, enabling taxonomic identification. Morphological characteristics allowed the identification of adult mites of the species D. pteronyssinus. Therefore, this work presents the first record of allergic dermatitis caused by this arthropod in Southern Brazil.