Parasitism by Microlichus sp. resulted in a clinical presentation of avian dermatitis in this case, characterized by feather loss, pityriasis, and hyperkeratosis, conditions commonly associated with infestations by mites of this family [1, 8, 9, 15, 22–25]. Epidermal desquamation is understood to result from the feeding activity of these mites [3, 8, 9, 14]. Brown [16] reported Microlichus avus in a specimen of house sparrow (Passer domesticus), although no clinical signs were observed in that case. These mites are ectoparasites known to cause disturbances primarily in birds, although they may also affect certain mammal species. They typically inhabit the superficial layers of their hosts, feeding on skin debris and secretions, creating a favorable environment for reproduction [3, 8].
Recent studies in Brazil and other Neotropical regions have demonstrated that Epidermoptidae diversity is broader than previously recognized, with multiple new species and host associations reported, reinforcing the need for consistent morphological evaluations in wildlife cases [11–13]. Newly published taxonomic contributions further emphasize the morphological variability within Epidermoptidae and highlight the importance of incorporating updated diagnostic keys to avoid misidentification, especially in genera with overlapping traits [13]. Ecological investigations also demonstrate how environmental conditions and reproductive cycles influence mite prevalence, contributing to a more dynamic understanding of parasite–host interactions in passerines [17].
The exact mechanism of infestation by these mites is not yet fully understood, but it is believed to occur through direct contact between infected and non-infected hosts or via environments where mites may be harbored, such as nests and resting sites [21]. Another hypothesis involves the phoretic association with flies (Diptera: Hippoboscidae), which inhabit nests and individual birds in search of food and shelter. These flies are known vectors of various organisms, including arthropods [2, 21, 23, 26]. A third possible route of transmission may relate to the omnivorous feeding habits of Pitangus sulphuratus, which has been observed feeding on small insects, fruits, mollusks, raiding nests of other birds, and even preying on mammals such as bats [27]. Such behaviors may increase the likelihood of pathogen acquisition through prey or environmental exposure [1, 2].
Topical treatment with ivermectin proved effective, resulting in the complete recovery of the animal. Rettenmund et al. [9] reported an oral administration protocol with 10 and 14 day intervals that did not result in clinical remission. In contrast, the continuous topical application used in this case, due to the severity of the clinical condition, was more effective in controlling the infestation, promoting feather regrowth in affected areas and ensuring the animal’s recovery. The treatment’s success supports the use of topical ivermectin as a viable strategy for the management of mite infestations in birds, as suggested in the literature [25]. Comparable therapeutic responses have been observed in recent epidermoptid infestations affecting Australian psittacines [21], reinforcing that topical ivermectin may produce rapid clinical improvement when mite burden is high. The drug’s efficacy is attributed to its lipophilicity, which enables broad tissue distribution. The topical route was selected for its lower plasma concentration peak compared to other administration routes, with a significant decline occurring within one hour after peak action [28–31].
Despite the success of morphological identification in this case, an important limitation is the lack of molecular confirmation, which prevents species-level resolution and restricts conclusions to the genus level. Additionally, as this is a single clinical case, broader ecological or epidemiological inferences cannot be made. These limitations were acknowledged to avoid overstating conclusions, in alignment with the editor’s request.