Beak and feather disease viruses circulating in Cape parrots (Poicepahlus robustus) in South Africa

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.

The phylogenetic and phylogeographic landscape of the beak and feather disease virus, 1996-2022

The beak and feather disease virus (BFDV), causative agent of Psittacine beak and feather disease (PBFD), is a highly fatal and widespread virus that infects both the wild and captive Psittaciformes around the world. The BFDV genome is a ssDNA of approximately 2 kb in size, making it among the smallest known pathogenic viruses. Though, the virus is placed in Circoviridae family of the Circovirus genus, there is no classification system on clade and sub-clade level according to the International Committee on Taxonomy of Viruses and the strains are grouped on the bases of geographic locations. Thus, we provide the latest and robust phylogenetic classification of BFDVs in this study based on full-length genomic sequences, grouping all the available 454 strains detected during 1996-2022 into two distinct clades, e.g., GI and GII. The GI clade is further divided into six sub-clades (GI a-f), while GII into two sub-clades (GII a and b). In addition, the phylogeographic network identified high variability among the BFDV strains, showing several branches, where all the branches are connected to four strains, e.g., BFDV-ZA-PGM-70A-2008-South_Africa (GenBank ID: HM748921.1), BFDV-ZA-PGM-81A-2008-South_Africa (GenBank ID: JX221009.1), BFDV14-2010-Thailand (GenBank ID: GU015021.1) and BFDV-isolate-9IT11-2014-Italy (GenBank ID: KF723390.1). Furthermore, we identified 27 recombination events in the rep (replication-associated protein) and cap (capsid protein) coding regions using the complete genomes of BFDVs. Similarly, the amino acids variability analysis indicated that both the rep and cap regions are highly variable with values exceeding the variability coefficient estimation limit of 1.00, speculating the possible amino acids drift with the emergence of new strains. The findings provided in this study may offer the latest phylogenetic, phylogeographic and evolutionary landscape of the BFDVs.

Recovery from Beak and Feather Disease Virus Infection in a Cape Parrot (Poicephalus robustus) Population in South Africa

Psittacine beak and feather disease (PBFD) is one of the most important viral diseases affecting parrot species worldwide. Outbreaks of PBFD have been reported in wild endemic and endangered South African Cape Parrots (Poicephalus robustus), most recently in 2008. A previous study of wild Cape Parrots in the Eastern Cape region of South Africa in 2010-11 found 34/49 birds positive for beak and feather disease virus (BFDV), the causative agent of PBFD, showing that the outbreak was still ongoing. The present study (2015-16) screened 30 blood samples from the same Cape Parrot population for BFDV infection by PCR: all parrots were found to be BFDV DNA-negative, which showed both that BFDV infection in the region has declined and that the parrot population has recovered. Our data contribute to the important negative data set which permits monitoring the progress of BFDV infections in wild Psittaciformes. We recommend a PCR method with universal BFDV primers as a quick, easy, and consistent diagnostic test for BFDV detection.

High Prevalence of Novel Beak and Feather Disease Virus in Sympatric Invasive Parakeets Introduced to Spain From Asia and South America

The psittacine beak and feather disease (PBFD) is a globally widespread infectious bird disease that mainly affects species within the Order Psittaciformes (parrots and allies). The disease is caused by an avian circovirus (the beak and feather disease virus, BFDV), which is highly infectious and can lead to severe consequences in wild and captive populations during an outbreak. Both legal and illegal trading have spread the BFDV around the world, although little is known about its prevalence in invasive parrot populations. Here, we analyze the BFDV prevalence in sympatric invasive populations of rose-ringed (Psittacula krameri) and monk parakeets (Myiopsitta monachus) in Southern Spain. We PCR-screened 110 blood samples (55 individuals from each species) for BFDV and characterized the genotypes of five positives from each species. About 33% of rose-ringed parakeets and 37% of monk parakeets sampled were positive for BFDV, while neither species showed disease symptoms. The circovirus identified is a novel BFDV genotype common to both species, similar to the BFDV genotypes detected in several parrot species kept in captivity in Saudi Arabia, South Africa and China. Our data evidences the importance of an accurate evaluation of avian diseases in wild populations, since invasive parrots may be bringing BFDV without showing any visually detectable clinical sign. Further research on the BFDV prevalence and transmission (individual–individual, captive–wild and wild–captive) in different bird orders and countries is crucial to understand the dynamics of the viral infection and minimize its impact in captive and wild populations.

Hygiene and biosecurity protocols reduce infection prevalence but do not improve fledging success in an endangered parrot

Emerging Infectious Diseases (EIDs) are recognised as global extinction drivers of threatened species. Unfortunately, biodiversity managers have few tested solutions to manage them when often the desperate need for solutions necessitates a response. Here we test in situ biosecurity protocols to assess the efficacy of managing Psittacine beak and feather disease (PBFD), one of the most common and emergent viral diseases in wild parrots (Psittaciformes) that is currently affecting numerous threatened species globally. In response to an outbreak of PBFD in Mauritius “echo” parakeets (Psittacula eques), managers implemented a set of biosecurity protocols to limit transmission and impact of Beak and feather disease virus (BFDV). Here we used a reciprocal design experiment on the wild population to test whether BFDV management reduced viral prevalence and viral load, and improved nestling body condition and fledge success. Whilst management reduced the probability of nestling infection by approximately 11% there was no observed impact on BFDV load and nestling body condition. In contrast to expectations there was lower fledge success in nests with added BFDV biosecurity (83% in untreated vs. 79% in treated nests). Our results clearly illustrate that management for wildlife conservation should be critically evaluated through targeted monitoring and experimental manipulation, and this evaluation should always focus on the fundamental objective of conservation.

Psittacid Adenovirus-2 infection in the critically endangered orange-bellied parrot (Neophema chrysogastor): A key threatening process or an example of a host-adapted virus?

Psittacid Adenovirus-2 (PsAdv-2) was identified in captive orange-bellied parrots (Neophema chrysogastor) during a multifactorial cluster of mortalities at the Adelaide Zoo, South Australia, and an outbreak of Pseudomonas aeruginosa septicaemia at the Tasmanian Department of Primary Industries, Parks, Water and Environment captive breeding facility, Taroona, Tasmania. This was the first time that an adenovirus had been identified in orange-bellied parrots and is the first report of PsAdv-2 in Australia. To investigate the status of PsAdv-2 in the captive population of orange-bellied parrots, 102 healthy birds from five breeding facilities were examined for the presence of PsAdv-2 DNA in droppings and/or cloacal swabs using a nested polymerase chain reaction assay. Additionally, eight birds released to the wild for the 2016 breeding season were similarly tested when they were recaptured prior to migration to be held in captivity for the winter. PsAdv-2 was identified in all breeding facilities as well as the birds recaptured from the wild. Prevalence of shedding ranged from 29.7 to 76.5%, demonstrating that PsAdv-2 is endemic in the captive population of orange-bellied parrots and that wild parrots may have been exposed to the virus. PsAdv-2 DNA was detected in both cloacal swabs and faeces of the orange-bellied parrots, but testing both samples from the same birds suggested that testing faeces would be more sensitive than cloacal swabs. PsAdv-2 was not found in other psittacine species housed in nearby aviaries at the Adelaide Zoo. The source of the infection in the orange-bellied parrots remains undetermined. In this study, PsAdv-2 prevalence of shedding was higher in adult birds as compared to birds less than one year old. Preliminary data also suggested a correlation between adenovirus shedding prevalence within the breeding collection and chick survival.

Trade and conservation implications of new beak and feather disease virus detection in native and introduced parrots

Psittacine beak and feather disease (PBFD), caused by Beak and feather disease virus (BFDV), has spread rapidly around the world, raising concerns for threatened species conservation and biosecurity associated with the global pet bird trade. The virus has been reported in several wild parrot populations, but data are lacking for many taxa and geographical areas with high parrot endemism. We aimed to advance understanding of BFDV distribution in many data-deficient areas and determine phylogenetic and biogeographic associations of the virus in 5 parrot species across Africa, the Indian Ocean islands, Asia, and Europe and focused specifically on the highly traded and invasive Psittacula krameri. Blood, feather, and tissue samples were screened for BFDV through standard polymerase chain reaction. Isolates obtained from positive individuals were then analyzed in a maximum likelihood phylogeny along with all other publically available global BFDV sequences. We detected BFDV in 8 countries where it was not known to occur previously, indicating the virus is more widely distributed than currently recognized. We documented for the first time the presence of BFDV in wild populations of P. krameri within its native range in Asia and Africa. We detected BFDV among introduced P. krameri in Mauritius and the Seychelles, raising concerns for island endemic species in the region. Phylogenetic relationships between viral sequences showed likely pathways of transmission between populations in southern Asia and western Africa. A high degree of phylogenetic relatedness between viral variants from geographically distant populations suggests recent introductions, likely driven by global trade. These findings highlight the need for effective regulation of international trade in live parrots, particularly in regions with high parrot endemism or vulnerable taxa where P. krameri could act as a reservoir host.

Beak and feather disease virus in wild and captive parrots: an analysis of geographic and taxonomic distribution and methodological trends

Psittacine beak and feather disease (PBFD) has emerged in recent years as a major threat to wild parrot populations and is an increasing concern to aviculturists and managers of captive populations. Pathological and serological tests for screening for the presence of beak and feather disease virus (BFDV) are a critical component of efforts to manage the disease and of epidemiological studies. Since the disease was first reported in the mid-1970s, screening for BFDV has been conducted in numerous wild and captive populations. However, at present, there is no current and readily accessible synthesis of screening efforts and their results. Here, we consolidate information collected from 83 PBFD- and BFDV-based publications on the primary screening methods being used and identify important knowledge gaps regarding potential global disease hotspots. We present trends in research intensity in this field and critically discuss advances in screening techniques and their applications to both aviculture and to the management of threatened wild populations. Finally, we provide an overview of estimates of BFDV prevalence in captive and wild flocks alongside a complete list of all psittacine species in which the virus has been confirmed. Our evaluation highlights the need for standardised diagnostic tests and more emphasis on studies of wild populations, particularly in view of the intrinsic connection between global trade in companion birds and the spread of novel BFDV strains into wild populations. Increased emphasis should be placed on the screening of captive and wild parrot populations within their countries of origin across the Americas, Africa and Asia.

Emerging infectious disease or evidence of endemicity? A multi-season study of beak and feather disease virus in wild red-crowned parakeets (Cyanoramphus novaezelandiae)

Beak and feather disease virus (BFDV) is a single-stranded DNA virus that is the etiological agent of beak and feather disease in both wild and captive parrots. Given that BFDV is globally recognized as a conservation threat for wild parrots, between 2011-2013, red-crowned parakeets (Cyanoramphus novaezelandiae, n = 229), which are endemic to New Zealand, were captured in mist nets on Tiritiri Matangi Island and Hauturu-o-Toi/Little Barrier Island (LBI), New Zealand, for disease surveillance. Blood and feathers from all birds were tested by PCR for BFDV, and full genomes were recovered and sequenced. A subset of blood samples (n = 96) were tested for antibodies to BFDV by the haemagglutination inhibition (HI) test. A further 238 feather samples were obtained from red-crowned parakeets from three sites in the Wellington region of the North Island, and these were screened for BFDV. The DNA-based prevalence of BFDV infection determined on Tiritiri Matangi Island was 1.09% (CI 95 %, 0.1-3.9%); on Hauturu-o-Toi/LBI, 4.4% (95% CI, 0.5%-15.1%); on Kapiti Island, 3.4% (CI 95%, 1.1-7.8%); at the ZEALANDIA-Karori sanctuary, 1.6% (95% CI, 0-8.4%); and on Matiu-Somes Island, 0% (CI 95%, 0-12.3%). Seroprevalence for BFDV, indicating prior or current exposure, in the Tiritiri Matangi Island population, it was 2% (CI 95%, 0-10.1%), and in the Hauturu-o-Toi/LBI population was 14% (CI 95%, 5.3-27.9%). BFDV-positive birds showed no signs of clinical disease, with the exception of an individual bird obtained opportunistically from Shakespear Regional Park during the study period, which had classical signs of feather loss. Phylogenetic analysis of the 11 full genome sequences recovered from BFDV-positive red-crowned parakeets revealed evidence of ongoing viral flow between red-crowned parakeets and eastern rosellas (Platycercus eximius) in the Hauraki Gulf/Auckland region, with separate but closely related strains from the Wellington region of the North Island. This is the first study to report HI results for a New Zealand endemic parrot species, and the first epidemiological analysis of serial cross-sectional surveys in a BFDV-infected population of red-crowned parakeets in New Zealand. We postulate that although BFDV remains a threat to small, isolated or naïve populations of parrots globally, the low viral prevalence in this and other studies suggests that native parakeets in New Zealand may act as dead-end or spillover hosts.