Diagnostic Procedures and Available Techniques for the Diagnosis of Aspergillosis in Birds

Aspergillosis is a common and life-threatening disease in birds affecting single individuals and flocks. Acute and chronic forms of this mycotic disease have been known for centuries; however, antemortem diagnosis remains difficult. Reliable, rapid, and noninvasive diagnostic testing is desirable, especially for chronic aspergillosis cases, when other disease conditions may be present. Therefore, research has focused on the development and improvement of clinical diagnostic procedures and techniques. At present, a definitive diagnosis for aspergillosis is based on cumulative evidence from several diagnostic tests. Potential sources of fungal infection, predisposing factors, and management conditions may be identified during anamnesis. Suspect cases can be confirmed by clinical examination, radiology, or computed tomography. Additionally, results from a blood biochemistry panel, complete blood count, acute phase protein analysis, and protein electrophoresis may be used as ancillary tests to determine a patientʼs condition. Aspergillus antigen, toxin, and Aspergillus-specific antibody detections from blood samples may aid in determining a diagnosis, but are currently not considered reliable for all avian species. For most aspergillosis cases pathological and histopathological lesions are diagnostic and molecular biological assays are available to identify the fungal agent from biopsy or necropsy specimens. A definitive diagnosis is based on fungal identification with histopathological evidence demonstrating the fungal agent inside the affected tissue. However, endoscopic or laparoscopic samples submitted for fungal culture and subsequent identification are still regarded as valid for a clinical diagnosis of aspergillosis in birds. The current status, benefits, and disadvantages of diagnostic procedures and techniques for avian aspergillosis are provided to aid the avian practitioner in selecting a test protocol to determine a definitive diagnosis.