Incidence and detection of beak and feather disease virus in psittacine birds in the UAE

Prevalence, genotypes, and infection risk factors of psittacine beak and feather disease virus and budgerigar fledgling disease virus in captive birds in Hong Kong

Psittacine beak and feather disease virus (PBFDV) and budgerigar fledgling disease virus (BFDV) are significant avian pathogens that threaten both captive and wild birds, particularly parrots, which are common hosts. This study involved sampling and testing of 516 captive birds from households, pet shops, and an animal clinic in Hong Kong for PBFDV and BFDV. The results showed that PBFDV and BFDV were present in 7.17% and 0.58% of the samples, respectively. These rates were lower than those reported in most parts of Asia. Notably, the infection rates of PBFDV in pet shops were significantly higher compared to other sources, while no BFDV-positive samples were found in pet shops. Most of the positive samples came from parrots, but PBFDV was also detected in two non-parrot species, including Swinhoe's white-eyes (Zosterops simplex), which had not been reported previously. The ability of PBFDV to infect both psittacine and passerine birds is concerning, especially in densely populated urban areas such as Hong Kong, where captive flocks come into close contact with wildlife. Phylogenetic analysis of the Cap and Rep genes of PBFDV revealed that the strains found in Hong Kong were closely related to those in Europe and other parts of Asia, including mainland China, Thailand, Taiwan, and Saudi Arabia. These findings indicate the presence of both viruses among captive birds in Hong Kong. We recommend implementing regular surveillance for both viruses and adopting measures to prevent contact between captive and wild birds, thereby reducing the transmission of introduced diseases to native species.

Fluctuation of the prevalence of beak and feather disease virus in captive psittacines in Iran

Beak and feather disease virus (BFDV) is one of the most life-threatening viral agents infecting parrot species. In this study, we investigated fluctuation in the prevalence of beak and feather disease virus (BFDV) in captive psittacines in Iran. Two series of feather samples from different psittacine species, received between July 2019 and July 2021 (n = 1009) and between July 2021 and July 2022 (n = 2020), were examined for the presence of BFDV using the PCR method, and the host species distribution and temporal prevalence of BFDV within populations were calculated. The results showed a total viral prevalence of 26.86% and 26.88% within sample series 1 and 2, respectively. By examining both sample series, the prevalence of BFDV was found to be  the highest (P < 0.05) in Nymphicus hollandicus and the lowest (P < 0.05) in Psittacus erithacus, Myiopsitta monachus, Pyrrhura molinae, and Aratinga solstitialis. The viral prevalence was significantly higher (P < 0.05) within the series 1 than the series 2 samples only in Nymphicus hollandicus. Within series 2, the viral prevalence was significant (P < 0.05) in samples from Nymphicus hollandicus collected in March. This study indicates significant prevalence of BFDV in captive Nymphicus hollandicus populations and suggests that the fluctuation in the prevalence of BFDV could be due to the combined influence of host-species and temporal factors.

Survey of Beak and Feather Disease Virus (BFDV) in Guatemalan Neotropical Psittacine Birds

Beak and feather disease virus (BFDV), a circovirus, is the etiologic agent of psittacine beak and feather disease (PBFD), a progressive and often fatal disease in Psittaciformes. Even though neotropical psittacine species are more resistant to clinical infection than Old World species, BFDV is recognized as a threat to immunologically naïve wild psittacine flocks and its epidemiologic control is paramount for conservation efforts in Neotropical species. Samples were collected from multiple psittacine species, including Ara species, Amazona species, and the white-crowned parrot (Pionus senilis) from the only rescue center in Guatemala with formal psittacine rehabilitation and reintroduction programs. A total of 117 birds, with 101 adults and 16 juveniles of unknown sex, were tested for BFDV by means of a real-time polymerase chain reaction (PCR) assay. The BFDV prevalence found in this study was 0%, (95% confidence interval, 0%-6.0%). Seven 2-8-year-old scarlet macaws (Ara macao cyanoptera) with positive results from previous surveys by conventional PCR yielded negative results in this study, suggesting complete infection resolution.

Prevalence of Aves Polyomavirus 1 and Beak and Feather Disease Virus From Exotic Captive Psittacine Birds in Chile

Avian polyomavirus disease and psittacine beak and feather disease (PBFD) are both contagious viral diseases in psittacine birds with similar clinical manifestations and characterized by abnormal feathers. To determine the prevalence of Aves polyomavirus 1 (APyV) and beak and feather disease virus (BFDV) in captive, exotic psittacine birds in Chile, feathers from 250 psittacine birds, representing 17 genera, were collected and stored during the period 2013-2016. Polymerase chain reaction testing was used to detect APyV and BFDV were detected in feather bulb samples. The results indicated that 1.6% (4/250) of the samples were positive for APyV, 23.2% (58/250) were positive to BFDV, and 0.8% (2/250) were positive to both APyV and BFDV. This is the first report, to our knowledge, of APyV and BFDV prevalence in captive, exotic psittacine birds in South America. Analysis of 2 Chilean partial sequences of the gene encoding agnoprotein 1a (APyV) and the replication-associated protein (BFDV) extends the knowledge of genomic variability for both APyV and BFDV isolates and their spectrum of hosts. No geographical marker was detected for the local isolates.

Development and use of a triplex real-time PCR assay for detection of three DNA viruses in psittacine birds

Aves polyomavirus 1, psittacine beak and feather disease virus, and psittacid herpesvirus 1 are important pathogens of psittacine birds with the potential to cause substantial morbidity and mortality. Using publically available nucleotide sequences, we developed and validated a triplex real-time PCR (rtPCR) assay to rapidly detect these 3 viruses. The assay had high analytical sensitivity, detecting <6 copies of viral DNA per reaction, and 100% analytical specificity, showing no cross-reactivity with 59 other animal pathogens. Archived formalin-fixed, paraffin-embedded tissues from psittacine birds diagnosed at postmortem as infected with each of the viruses as well as virus-negative birds were used to validate the utility of the assay. Birds were selected for the positive cohort if they showed histologic evidence of infection (i.e., characteristic inclusion bodies in tissues); birds in the negative cohort had final diagnoses unrelated to the pathogens of interest. The triplex rtPCR assay confirmed 98% of histopathology-positive cases, and also identified subclinical infections that were not observed by histologic examination, including coinfections. Birds that tested positive only by rtPCR had significantly higher cycle threshold values compared to those with histologic evidence of infection. Positive, negative, and overall percentage agreements as well as the kappa statistic between the results of the assay and histopathology were high, demonstrating the usefulness of the assay as a tool to confirm disease diagnoses, and to improve detection of subclinical infections.

HEALTH ASSESSMENT OF CAPTIVE PSITTACINE SPECIES IN PRERELEASE PROGRAMS AT COSTA RICAN RESCUE CENTERS

With stricter laws regulating the capture and possession of wild animals in Costa Rica, local wildlife-rescue centers have been overwhelmed by an influx of confiscated or relinquished illegal pets, specifically of psittacine species. As part of a nationwide health-assessment program targeting these centers, 122 birds representing five psittacine species ( Ara macao, Amazona autumnalis, Amazona auropalliata, Amazona farinosa, Aratinga finschi) and one hybrid macaw ( Ara macao × Ara ambiguus) were examined and tested between January 2011 and October 2012. Physical examination, hematology, and serum biochemical analyses were performed. Blood and feathers were tested for psittacine beak and feather disease virus (PBFDV) and avian polyomavirus (APV) via PCR. A DNA-based prevalence and sequence analysis characterized the strains of PBFDV and APV isolated. Physical abnormalities observed in 36% of the 122 birds examined were limited to thin body condition and poor feather quality. None of the feather abnormalities were characteristic of disease caused by either PBFDV or APV. Results of hematological and biochemical analyses were within normal limits except for five birds with leukocytosis and heterophilia, three birds with uric acid values above 16 mg/dl, and two additional birds with AST values above 400 IU/L. No hemoparasites were detected during blood smear examination. Overall prevalences of 9.8% (12/122) for PBFDV and 3.3% (4/122) for APV were documented, with only one bird testing positive for both PBFDV and APV. Birds from two of the eight centers were negative for both viruses. Findings from this study constitute the beginning of a standardized surveillance program for Costa Rican rescue centers, targeting the management of avian species enrolled in propagation and reintroduction programs and expanding of the spectrum of pathogen surveillance and husbandry recommendations in prerelease centers.

Detection and Characterization of Circovirus in Canary Flocks

Circovirus infections have been documented in adult and nestling canaries (Fringillidae) but the distribution of the virus in the world is not yet known. In captive canary flocks, Circovirus infections have been reported based on the clinical observations. In this study, the presence of both canary circovirus (CaCV) and chicken anemia virus (CAV) in canary flocks was investigated. Virus strains were detected by PCR and direct sequencing of amplified products. Nucleotide sequences were aligned and compared with existing data in GenBank. PCR identified CaCV-positive birds, giving an overall positivity rate of 25%, but all samples were negative for CAV. According to the sequencing data, three distinct strains were identified. Our results indicated a relationship between genetic variation in the replicase gene ( rep) and the geographic regions as well as the feasibility of using the rep gene for virus detection and molecular epidemiology investigations. We are reporting detection and characterization of canary circovirus based on the rep gene. Sequencing results and sequence identity analysis revealed that the rep gene could be used for detecting and discriminating the members of family Circoviridae. This manuscript is the first report of canary circovirus in Iran and of three new strains in the world.

Complete Genome Sequence of Beak and Feather Disease Virus Isolated from an African Grey Parrot in China in 2017

The complete nucleotide (nt) sequence of beak and feather disease virus (BFDV) was determined. The viral genome consists of 1,991 nt, including an 870-nt open reading frame 1 (ORF1), a 744-nt ORF2, a conserved stem-loop structure, and the second hairpin. This is the first reported detection of BFDV in an infected African grey parrot in China.

Molecular detection and characterization of beak and feather disease virus in psittacine birds in Tehran, Iran

Beak and feather disease virus (BFDV), a member of genus circovirus, is a small, non-enveloped, single stranded DNA virus. Although BFDVs are among the most well studied circoviruses, there is little to no information about BFDVs in Iran. The aim of the present study was to detect and identify BFDV molecules from the birds referred to the avian clinic of The Faculty of Veterinary Medicine, Tehran University, Iran. A total of 55 DNA samples were extracted from birds from nine different species of the order psittaciformes. A robust conventional polymerase chain reaction (PCR) was applied to detect the rep gene of the virus. Ten out of 55 samples, from four different species, were tested positive for BFDVs in PCR (Melopsittacus undulates (4), Psittacula Krameri (3), Psittacus erithacus (2), Platycercus eximius (1)). Molecular identification of the detected BFDVs was performed based on their rep gene sequences. The phylogenetic analysis revealed that the Iranian BFDVs from this study were clustered into four genetically distinct clades belonging to different genetic subtypes of BFDVs (L1, N1, T1, and I4). Although the relation between the samples and their related subtypes in the tree are discussed, further studies are needed to elucidate the host specificity and incidence of the BFDVs from different genetic subtypes.

Development and evaluation of TaqMan real-time PCR assay for detection of beak and feather disease virus

Psittacine beak and feather disease (PBFD) is one of the most significant viral diseases in psittacine birds. The aim of the presented study was to develop a highly specific and sensitive TaqMan real-time PCR assay for universal detection of beak and feather disease virus (BFDV). Primers and a hydrolysis probe were selected on the highly conserved regions belonging to the ORF1 of the BFDV genome which were identified by aligning 814 genomic sequences downloaded from the GenBank database. The evaluation of the reaction parameters suggested a reaction efficiency of 97.1%, with consistent detection of 10¹ virus copies/μl of nucleic acid extract. The low values of standard deviation and coefficient of variation indicate a high degree of reproducibility and repeatability. The diagnostic applicability of the assay was proven on 36 BFDV positive and 107 negative specimens of psittacine origin representing 28 species. The assay showed a 100% ability to detect distinct genetic variants of the virus. Our data suggest that the presented TaqMan real-time PCR represents a specific, sensitive and reliable assay facilitating the molecular detection of BFDV.

Systemic Clinical and Metabolic Diseases

Like other animals pet and companion birds are also prone to systemic illness. This is presented in the form of certain clinical signs and symptoms which is known as “ sick-bird syndrome.”