Sharman Hoppes

Use of avian bornavirus isolates to induce proventricular dilatation disease in conures

The fulfillment of Koch’s postulates shows that the virus causes proventricular dilatation disease in parrots.

Molecular characterization of the cloacal microbiota of wild and captive parrots.

The gastrointestinal microbiota plays a fundamental role in health and disease. Only limited data are available about the composition of the intestinal microbiota of captive animals compared to those of wild animals. The aim of the present study was to characterize the cloacal microbiota of apparently healthy wild and captive parrots. A total of 16 parrots, 8 wild and 8 captive, belonging to 3 different species, were used in this study. Cloacal material was collected via cloacal swabbing. DNA was extracted and 16S rRNA genes were amplified using universal bacterial primers. Constructed 16S rRNA gene clone libraries were compared between groups. A total of 518 clones were analyzed, and 49 operational taxonomic units (OTUs) were identified. The OTUs were classified in 4 bacterial phyla: Firmicutes (72.9%), Proteobacteria (14.9%), Actinobacteria (12%), and Bacteroidetes (0.2%). Bacterial diversity was significantly lower in wild birds than in captive birds. Principal component analysis based on the Unifrac distance metric indicated that the cloacal microbiota differed between wild and captive parrots. Staphylococcus saprophyticus was significantly more abundant in wild birds, while Escherichia coli was significantly more abundant in captive birds. In conclusion, wild and captive parrots appear to have differences in the composition of their cloacal bacterial microbiota. The clinical significance of these differences remains to be determined.

Unusual and severe lesions of proventricular dilatation disease in cockatiels (Nymphicus hollandicus) acting as healthy carriers of avian bornavirus (ABV) and subsequently infected with a virulent strain of ABV

A flock of 14 apparently healthy cockatiels, purchased from a single aviary, was tested for the presence of avian bornavirus (ABV). Twelve birds were found to be intermittently shedding ABV, predominantly genotype 4. Four of the cockatiels known to be shedding ABV4 were subsequently challenged with the tissue culture derived, virulent M24 strain of ABV4. The challenged birds remained in apparent good health until day 92 when one was found dead. The remaining three birds began to exhibit severe neurologic signs, ataxia and convulsions on day 110 and were euthanized. On necropsy, all four birds showed mild proventricular enlargement. In contrast, histopathological examination showed unusually severe and widespread tissue lesions. These included massive lymphocytic infiltration and lymphoid nodule formation within and around the ganglia throughout the gastrointestinal tract. There were similar lesions in the medullary cords of the adrenal gland, heart, spleen, liver, kidney, lungs, pancreas, testes and ovary. Immunohistochemistry demonstrated ABV P antigen not only in the cells of the central and autonomic nervous systems, but also within the mononuclear cells infiltrating the various organs. Two healthy cockatiels, one of which was a known ABV carrier, were inoculated with uninfected tissue culture cells and euthanized on day 150. These birds showed no gross lesions of proventricular dilatation disease but had a mild lymphocytic infiltration in their liver, spleen, and kidneys. Prior infection with ABV did not therefore confer significant immunity on these birds, and may have resulted in increased disease severity following challenge.

Disposition and Analgesic Effects of Fentanyl in White Cockatoos (Cacatua alba)

Abstract Fentanyl is a mu opioid agonist with 80–100 times the analgesic potency of morphine. Fentanyl is used in several mammalian species for relief of severe pain, but its use has not been investigated in psittacine birds. To determine the pharmacologic disposition of fentanyl in healthy white cockatoos (Cacatua alba), we measured fentanyl plasma concentrations in sequentially collected samples after administration of fentanyl at 0.01 or 0.02 mg/kg IM. To investigate the analgesic effects of fentanyl in conscious cockatoos, we compared the change in pre- and posttreatment levels of electrical and thermal noxious stimuli necessary to elicit a withdrawal response in birds administered fentanyl at 2 different doses (0.02 mg/kg IM or 0.2 mg/kg SC) and those given saline. Fentanyl was rapidly absorbed and plasma concentrations declined with an elimination half-life of 1.2–1.4 hours. Plasma concentrations considered to be analgesic in humans were maintained for at least 2 hours with the 0.02 mg/kg dose. However, no significant difference was found in analgesic response between birds given saline and those given fentanyl at 0.02 mg/kg IM. Although the 0.2 mg/kg SC dose provided significant analgesia in some birds, fentanyl at this dose is not recommended as a routine analgesic agent because a large volume of drug must be injected and this dose causes hyperactivity in some birds.

The Isolation, Pathogenesis, Diagnosis, Transmission, and Control of Avian Bornavirus and Proventricular Dilatation Disease

Proventricular dilatation disease (PDD) is a common infectious neurologic disease of birds comprising a dilatation of the proventriculus by ingested food as a result of defects in intestinal motility, which affects more than 50 species of psittacines, and is also known as Macaw wasting disease, neuropathic ganglioneuritis, or lymphoplasmacytic ganglioneuritis. Definitive diagnosis of PDD has been problematic due to the inconsistent distribution of lesions. Since its discovery, avian bornavirus (ABV) has been successfully cultured from the brains of psittacines diagnosed with PDD, providing a source of antigen for serologic assays and nucleic acid for molecular assays. This article provides evidence that ABV is the etiologic agent of PDD. Recent findings on the transmission, epidemiology, pathogenesis, diagnosis, and control of ABV infection and PDD are also reviewed.

Proventricular Dilatation Disease in Cockatiels (Nymphicus hollandicus) After Infection With a Genotype 2 Avian Bornavirus

Abstract An isolate of genotype 2 avian bornavirus (ABV) was recovered from a cockatiel (Nymphicus hollandicus) that was euthanatized for an unrelated lesion and showing no clinical evidence of proventricular dilatation disease (PDD). On histopathologic examination, mild inflammatory lesions were present in the heart and brain, but gastrointestinal lesions characteristic of classic PDD were not observed. To investigate if this ABV2 isolate had reduced virulence, the virus was propagated in duck embryo fibroblasts and inoculated into 2 adult cockatiels by the oral and intramuscular routes. One bird developed clinical signs on day 33 and was euthanatized on day 36. The second challenged bird developed clinical signs on day 41 and was euthanatized on day 45. At necropsy, the proventriculus of both birds was slightly enlarged. Histopathologic examination showed lesions typical of PDD in the brain, spinal cord, heart, adrenal gland, and intestine. A control, uninoculated cockatiel was apparently healthy when euthanatized on day 50. These results show that ABV2 is now the second ABV genotype to be formally shown to cause PDD.

Avian bornavirus and proventricular dilatation disease: Diagnostics, pathology, prevalence, and control

Avian bornavirus (ABV) has been shown the cause of proventricular dilatation disease (PDD) in psittacines. Many healthy birds are infected with ABV, and the development of PDD in such cases is unpredictable. As a result, the detection of ABV in a sick bird is not confirmation that it is suffering from PDD. Treatment studies are in their infancy. ABV is not restricted to psittacines. It has been found to cause PDD-like disease in canaries. It is also present at a high prevalence in North American geese, swans, and ducks. It is not believed that these waterfowl genotypes can cause disease in psittacines.

Mycotic Keratitis in a Blue-fronted Amazon Parrot (Amazona aestiva)

Abstract Mycotic keratitis is most commonly reported in horses and humans and is rarely reported in birds. We diagnosed mycotic keratitis, localized to the left eye, in an adult blue-fronted Amazon parrot (Amazona aestiva). The ophthalmic examination revealed a diffuse yellow-green haze encompassing the entire surface of the left cornea. Diffuse fluorescein uptake occurred in the entire cornea. The right eye appeared normal. Aspergillus fumigatus was isolated on conjunctival culture. The affected eye was enucleated because of the birds discomfort and the poor prognosis for successful treatment. Histopathologic examination revealed a severe granulomatous keratitis with intracorneal fungal hyphae and corneal perforation. Multinucleated giant cells and fungal hyphae were present within the anterior chamber. Aspergillus fumigatus is an uncommon cause of keratitis in birds but should be considered as a potential cause of refractory ulcers.

The Detection of Avian Bornavirus Within Psittacine Eggs

Avian bornavirus (ABV) is a known cause of proventricular dilatation disease in parrots and encephalitis in waterfowl and is a significant cause of both morbidity and mortality in captive birds. Transmission is thought to occur primarily by the fecal-oral route. In an aviary setting, controlling the disease involves a thorough understanding of the complete transmission cycle, including determining whether vertical transmission occurs. In this study, vertical transmission of ABV was evaluated by using 61 eggs obtained from birds in 2 aviaries where proventricular dilatation disease was prevalent, and the presence of ABV had been confirmed by fecal reverse transcription-polymerase chain reaction by using a primer set designed to detect ABV M protein. The contents of these eggs were then tested for the presence of ABV RNA. Of the eggs tested, 10 were determined to contain ABV RNA. These eggs ranged from apparently nonviable to those that contained developing embryos. ABV was detected in the brain tissue of 2 embryos. It remains to be proven that infected chicks can hatch from these eggs to complete the vertical transmission cycle; however, these findings suggest that vertical transmission of ABV may occur.

Granulomatous encephalomyelitis and intestinal ganglionitis in a spectacled Amazon parrot (Amazona albifrons) infected with Mycobacterium genavense.

An approximately 30-year-old male spectacled Amazon parrot (Amazona albifrons) was presented with a 2-week history of ataxia, head shaking, weight loss and seizures. Gross findings on necropsy examination included atrophy of the musculature, ruffled feathers and minimal epicardial and abdominal fat. Microscopically, there were perivascular cuffs of macrophages with fewer lymphocytes in the grey and white matter of the brain and spinal cord. These lesions were accompanied by gliosis and mild vacuolation of the white matter. In the small intestine, up to 70% of the intestinal ganglia were effaced by infiltrates of macrophages and fewer lymphocytes. The intestinal lamina propria contained multiple inflammatory aggregates of a similar nature. Ziehl-Neelsen staining revealed the presence of numerous bacilli within the cytoplasm of macrophages in the central nervous system (CNS) and enteric ganglia. Amplification of the DNAJ gene confirmed a mycobacterial infection and subsequent polymerase chain reaction (PCR) using a species-specific primer confirmed the aetiology as Mycobacterium genavense. Infection of the CNS with Mycobacterium spp. is uncommon and has not been previously reported in a parrot. This case is unusual in that the organism exhibited tropism for neural tissue.