Comparison of diagnostic tools for the detection of aspergillosis in blood samples of experimentally infected falcons

Abstract

Antemortem diagnosis of avian aspergillosis is very challenging. Diagnostic assays using blood samples would aid in an early and more definitive diagnosis. In the current study, detection of anti-Aspergillus antibodies, Aspergillus antigen, and Aspergillus toxin (fumigaclavine A), protein electrophoresis and measurement of acute-phase protein concentrations were performed on serum of 18 adult and plasma of 21 juvenile gyr-saker hybrid falcons (Falco rusticolus x Falco cherrug). Adult (n = 15) and juvenile (n = 18) falcons were experimentally inoculated with different dosages of the same strain of Aspergillus fumigatus and an additional three falcons from each age group were used as uninfected control animals. Blood samples were collected prior to inoculation and at 28 days postinoculation. Of the 33 inoculated falcons, 16 demonstrated clinical signs (vomiting, greenish urates, dyspnea, ruffled feathers) commonly associated with aspergillosis and in 14 falcons necropsy revealed aspergillosis granulomas confirmed by mycology and histopathology. Positive galactomannan results were rare, with only 3/15 positive samples from adult falcons and none in the juvenile birds. Most of the inoculated falcons showed an increase of serum amyloid A (66.7%) and haptoglobin (70.4%), but fumigaclavine A was not detected in the blood from any of the experimental animals. Elevated antibody indices were detected in 96.7% of the inoculated birds, but also in 66.7% of the controls. Significant decreases in albumin:globulin ratio were obvious in 81.5% of the inoculated birds, including 100% of the birds with granulomas. Blood from falcons with granulomas demonstrated significantly increased concentration values of alpha 2 and β globulins, decreased percentages of prealbumin and albumin, and increased percentages of alpha 2 and β globulins compared to inoculated falcons without granulomas. In conclusion, acute-phase proteins and the electrophoretic profile of birds challenged with A. fulmigatus show significant alterations, which in combination with other diagnostic procedures, assist in the early diagnosis of avian aspergillosis.