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Home / Case studies / #09
Case study #09
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The veterinarian of a Wildlife Recovery Center goes to the hospital emergency room with low-grade fever, facial pain, epiphora, brownish nasal mucus, and headache. A CT scan is performed, the results of which are seen in Image 1.
Image 1: Simple tomography of the paranasal sinuses showing occupation of the frontal sinuses, ethmoid cells and maxillary sinuses by hyperdense material in the center (long white arrows) and hypodense material in the periphery (small black arrows).
The animals received in the last month are reviewed, and the batch that arrived from the same park is suspected; a stork, a peregrine falcon, a common chicken, and a Colorado Duck, all of them with respiratory symptoms. The latter (Image 2), who arrived in critical condition, and whom the veterinarian treated with serum and antibiotic therapy, died a few days later.
Image 2: State in which the animal was found in the park pond.
The diagnosis raises suspicion of a zoonotic process; and to avoid possible infections in the Recovery center, all facilities are disinfected.
Post-mortem examination of the dead animal revealed macroscopically some granulomatous lesions in the air sacs (Image 3) and histologically the presence of filamentous structures (Image 4).
Image 3: Granulomatous lesions in the air sacs (yellow arrows) (source: Elisa Pérez Ramirez. CSIC-INIA)
Image 4: Filamentous structures (yellow arrows) (sourece: Elisa Pérez Ramirez. CSIC-INIA)
The lesions observed in the air sacs raise suspicion of a bacterial or fungal process and the following differential diagnosis is proposed:
- Avian mycobacteriosis
- Aspergillosis
- Psittacosis
Swabs were taken from the nodules of the air sacs and cultured in the specific media for each of the suspected processes. In the case of the center's veterinarian, samples were also taken for culture.
Secondary questions
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After 10 days of culturing the human and animal samples, a positive result was obtained on Sabouraud Agar. Staining the grown colony with lactophenol blue, and viewing it under an optical microscope, reveals the presence of the structures that appear in the image.
Main question
What could be the pathogen causing this process?
Solution
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The pathogen identified was Aspergillus fumigatus.
Aspergillosis is a fungal zoonosis of great importance in birds of prey in the wild and in captivity, although it is in this situation where it is especially manifested. The main causal agent is Aspergillus fumigatus, and less frequently, other species such as A. flavus, A. niger, A. nidulans or A. terreus. However, it is a multifactorial disease that is highly dependent on the environment, the immune system (immunosuppression) and management.
Infection occurs when the animal inhales conidia of Aspergillus spp. which penetrate the nasal passage very easily due to their small size and reach the respiratory tract, fixing and developing in the bronchi, lungs and air sacs. The clinical signs of aspergillosis are not specific for the disease and therefore it is not possible to establish a confirmatory diagnosis without the use of laboratory tests.
