Follow-up investigations on different courses of natural avian bornavirus infections in psittacines.

To study the course of natural avian bornavirus (ABV) infection, 63 psittacines of three bird collections where ABV had been demonstrated were investigated over a period of 1 yr. The psittacines were clinically observed and swabs of crop and cloaca as well as serum samples were collected three separate times at intervals of 2-6 mo. According to the results of detection of ABV RNA by reverse transcriptase polymerase chain reaction (RT-PCR) and of anti-ABV antibodies by indirect immunofluorescence assay (IIFA), 43 of the birds were found to be infected with ABV. Based on variations in virus shedding and antibody production in combination with the occurrence of proventricular dilatation disease (PDD) -related clinical signs, pathological findings, and lethal outcome, four different groups of infected psittacines and a fifth group of noninfected psittacines were identified. Group 1 comprised six birds with various courses of ABV infection and forms of clinical PDD. Groups 2-4 included all birds with subclinical ABV infections: Group 2 contained 13 birds that were consistently (subgroup A, 6 birds) or inconsistently (subgroup B, 7 birds) ABV positive by PCR and serology; group 3 was composed of 13 psittacines exhibiting only anti-ABV antibodies; and 8 birds that had positive ABV RNA detection in crop and cloaca, but did not develop anti-ABV specific antibodies, were classified in group 4. Twenty-three out of the 63 psittacines remained free of detectable ABV RNA or anti-ABV antibodies over the whole observation period (group 5). Based on the results, it seems that birds with high ABV RNA load in crop and cloaca combined with high anti-ABV antibodies have a high risk of the development of PDD, indicating that the humoral antibodies do not protect against the disease. The meaning of the detection of ABV RNA and antibodies at a low and inconsistent level for the single bird as well as for the epidemiology of the ABV infection remained unclear in this field study and needs to be further investigated.

Hematologic and plasma biochemical values of Spix's macaws (Cyanopsitta spixii).

The Spix's macaw (Cyanopsitta spixii) is considered the world's most endangered parrot, with the last wild bird disappearing in 2001 and only 74 birds in captivity. To establish hematologic and plasma biochemical reference ranges and to look for differences relative to sex, age, and season, we obtained blood samples from 46 captive Spix's macaws (23 male, 23 female) housed in aviaries at the Al Wabra Wildlife Preservation in the State of Qatar. No significant differences in hematologic or plasma biochemical values were found between females and males. Adult and juvenile birds differed in mean concentrations of glucose, total protein, amylase, cholesterol, and phosphorus; in percentages of heterophils and lymphocytes; and in the absolute lymphocyte count. Total protein, cholesterol, and phosphorus concentrations; hematocrit; and heterophil and lymphocyte counts differed significantly by season. Baseline hematologic and plasma biochemical ranges were established, which may be useful as reference values for clinicians working with this highly endangered species.

Physiology, diagnosis, and diseases of the avian reproductive tract.

Disorders of the reproductive system represent a large portion of both large and small domestic animal medicine. Although some disorders of this system have been extensively studied in birds, this science is still in its infancy, when compared to mammalian reproductive medicine. This may be due to several reasons, but the simple fact that birds are oviparous renders knowledge of mammalian reproductive anatomy, histology, physiology, and disease process, inapplicable to avian patients. Nevertheless, several specific diseases or conditions affecting the reproductive system of birds have been described. By integrating information about the comparative anatomy and physiology of birds, reports of the most common reproductive diseases of birds and utilizing the latest diagnostic techniques, especially videoendoscopy, the avian practitioner should be able to diagnose and properly treat a high percentage of the avian reproductive diseases.

Nucleotide sequence analysis of a C1 gene fragment of psittacine beak and feather disease virus amplified by real-time polymerase chain reaction indicates a possible existence of genotypes.

To investigate sequence diversity of psittacine beak and feather disease virus, samples collected from 31 psittacine species with or without clinical signs were tested for the presence of the viral genome. A real-time polymerase chain reaction was developed amplifying a 202 base pair fragment of the region encoding the capsid protein C1 and detecting 100 to 1000 genome equivalents. The nucleotide sequences of the polymerase chain reaction products showed 84.1 to 100% identity with no consistent pattern with regard to the infected bird species. Amino acid exchanges were concentrated mainly in five of the 42 deduced positions. Sequences obtained from an outbreak of acute beak and feather disease in lories clustered in a separate branch of a phylogenetic tree. Sequences in samples from African grey parrots with feather disorders grouped together, whereas those from the same species with immunosuppression clustered in other branches. These results indicate the possible existence of beak and feather disease virus genotypes.