Parasitismo pelo ácaro de sistema respiratório Sternostoma tracheacolum em um canário belga (Serinus canaria domestica) / Parasitism by the mite sternostoma tracheacolum in the respiratory system of a belgian canary (Serinus canaria domestica)

Background: The nasal mites of the Rhinonyssidae family include the highest diversity of mandatory hematophagous endoparasites of the respiratory system of birds. In general, these mites cause no significant lesions, except Sternostoma tracheacolum that invades the trachea, lungs and air sacs and may compromise breathing in birds. This study reports the death of a Belgian canary (Serinus canaria domestica) due to the parasitism by S. tracheacolum with an aggravating and concurrent pododermatitis infection. Case: A Belgian canary from a commercial bird flock, in which a high mortality rate had lately been recorded, was submitted to necropsy. Multiple blackened foci (1.0 mm in diameter) present in the trachea and the air sacs were subsequently identified as Sternostoma tracheacolum mites. Microscopically, there were diffuse and moderate infiltrates of lymphocytes, plasma cells, macrophages and heterophils within the tracheal submucosa and areas of fibrosis and osseous metaplasia of the tracheal cartilage. In the air sacs, there were multiple yellowish-brown foci of caseous necrosis, which were surrounded by inflammatory infiltrate of macrophages and multinucleated giant cells. In the lungs, there were foci of caseous necrosis surrounded by macrophages. In the tracheal lumen, mites sections were observed. Clusters of nucleated erythrocytes and brown granular pigment were seen within the longitudinal section of the mites. Prussian blue (Perls) special staining evidenced no hemosiderin content in the mite's tissues, in which no melanin could be detected, as well. Discussion: The parasitism by S. tracheacolum in canaries was first described in South Africa. In such cases, the mite induced clinical respiratory disease and killed the birds. Subsequently, reports of parasitism by these mites included several additional bird species, of which, Cockatiel (Nymphicus hollandicus) has been the most frequently affected and there are only a few reports of the condition in canaries. Clinically, hosts have difficulty breathing, exercise intolerance, coughing and sneezing. Depending on the severity, infection can persist for months or lead to death by suffocation or weakness. Clinical signs and death are related to the appearance of the lesions induced by the mites. Mite eggs are deposited in the lungs and the larvae hatch soon after oviposition. After the first meal, the female protonymph migrates to the posterior parabronchia, while the male protonymph remains in the lungs, where it completes the development. The adult mites full of eggs tend to occupy the parabronchia, the syrinx and the trachea. The negative results on Prussian blue and melanin bleach methods indicate that the dark pigment present within the tissues from the mites is neither hemosiderin nor melanin, respectively. In parasitism due to Plasmodium sp. (malaria), hemozoin, an iron-containing pigment associated with erythrocytic changes induced by the protozoan, has not been detectable by the Prussian blue staining. It is suggested that the dark color observed in the mites in this study could be associated with a similar pigment. The clinical respiratory diseases in birds are generally nonspecific. The paper focuses on the importance of the confirmation of the diagnosis by the necropsy and histopathological examinations, as well as on the characterization of this respiratory parasitic disease of birds.

Aspergilose em trinca-ferros (Saltator similis) competidores de canto / Aspergillosis in Green-winged saltators (Saltator similis) participants in bird singing competitions

Background: Aspergillosis is the most common mycosis in birds, which are considered potential host also susceptible to the infection by Aspergillus spp. The clinical signs of the disease are often related to the respiratory tract, although other organs or systems may be affected. Signs are generally either not specific or may be directly related to the extent of the lesions in the respiratory tract (rhinitis, changes in the vocalization and dyspnea). The aim of this study was to describe and characterize three cases of aspergillosis in Greenwinged saltators (Saltator similis), based on reference standard diagnostics of this mycosis. Cases: Three Green-winged adult male saltators that had been participating weekly for three months in bird singing contests were referred to a private veterinary clinic. The clinical evaluation revealed pronounced hoarseness (3/3) and intense dyspnea (1/3). The animals were allocated to a warmed (28º C) oxygen chamber at 65% relative humidity. All birds were nebulized with saline solution and hyaluronidase. In addition, the birds were treated orally with complex vitamins B, A, D and E and intravenously either with dexamethasone and doxycycline (Case 1), azithromycin (Case 2) or metronidazole-enrofloxacin combination (Case 3), in association with the use of Arnica Montana CH6 in the drinking water, and fluid therapy (5% glucose, Ringer-lactate and saline solution). In spite of the therapeutic treatments, the birds died three days after the hospitalization. The necropsy examination revealed: syrinx with yellowish content ranging from 2 to 5 mm diameter occluding the lumen (3/3) and the lungs were diffusely reddened (3/3) with yellowish areas of 2 mm (1/3). The histologic findings included proliferation of connective tissue in the mucosa and submucosa of the syrinx and granulomas formation in the lumen with necrotic centers that had large amounts of branched and septate hyphae with radiated arrangement. A large amount of hyphae were observed in granulomas in the lungs. The mycological culture (Sabouraud Dextrose Agar and Malt Extract Agar) of lung fragments and syrinx from all three birds allowed the isolation of colonies of Aspergillus fumigatus. Discussion: In Brazil, there are sparse reports of aspergillosis, mainly for native species of birds in captivity. The disease has been often diagnosed in migratory marine birds (treated at specific rehabilitation centers) and, occasionally, in wild birds or in animals raised in commercial poultry farms. The presence of fungal propagules in the respiratory system may cause colonization (a potential latent infection), condition that allows the fungal isolation from the lung tissue. However, under stress conditions or in a fall in immunity, as observed in this case study involving birds that intensively participate in singing competitions, it is often observed an evolution from the colonizing stage to range of clinical symptoms indicative of aspergillosis. The adoption of preventive measures to reduce the spreading of fungal propagules in the environment is essential, as well as proper feeding and hydration, a minimization of stress-related issues during animal management and transport, the rational use of drugs, and conditions that may favor the development of opportunistic mycoses, such as aspergillosis, which is the most common fungal disease in the world. The reported cases of aspergillosis in the lungs and syrinx of Green-winged saltators emphasizes the importance of a conclusive diagnosis for the disease based on the detection of fungal structures at the histopathological examination associated with the isolation of the agent in a fungal culture. The occurrence of aspergillosis may cause a significant loss of native bird species maintained in captivity, which is a serious concern when related to the preservation of the diversity of the Brazilian avian fauna.