ABSTRACT

Background and Aim: Psittacine beak and feather disease (PBFD), caused by beak and feather disease virus (BFDV), is a globally distributed circoviral disease that threatens companion and captive psittacines, commercial aviculture, wildlife rehabilitation, and the conservation of endangered parrots. This review synthesizes current knowledge of BFDV structure, genome organization, molecular pathogenesis, clinical expression, host range, epidemiology, genetic evolution, diagnostic methods, vaccine development, and control strategies. Evidence published from 1984 to 2026 was evaluated, with particular attention to recent advances in molecular surveillance, environmental sampling, serology, genomics, and vaccine platforms. BFDV is a small, non-enveloped, circular single-stranded DNA virus whose replication-associated and capsid proteins govern genome replication, nuclear trafficking, virion assembly, and antigenicity. Infection ranges from peracute systemic disease in juveniles to chronic feather and beak abnormalities, immunosuppression, secondary infections, and persistent subclinical carriage. Global molecular prevalence is estimated at 16.30%, while international bird trade, captive breeding networks, environmental persistence, intermittent shedding, and mixed-species contact facilitate viral dispersal. Rapid evolution, extensive recombination, divergent regional lineages, and multiple variants within individual birds complicate diagnostic assay design and may affect future vaccine coverage. Current diagnostic options include conventional and quantitative polymerase chain reaction, high-resolution melting analysis, loop-mediated isothermal amplification, multi-matrix sampling, environmental DNA surveillance, histopathology, and virus-like particle (VLP)- based serology. Vaccine candidates based on DNA, messenger RNA, plant-produced capsid protein, and thermostable VLPs have demonstrated encouraging immunogenicity but remain preclinical because target-species protection, heterologous challenge efficacy, juvenile safety, and duration of immunity remain unresolved. An integrated BFDV Resilience Framework is proposed around active biosurveillance, strategic intervention, and ecological and evolutionary monitoring coordinated through genomic intelligence. Effective control requires repeated multi-matrix testing, strict quarantine and hygiene, environmental monitoring, trade-linked screening, genomic surveillance, and cautious vaccine translation. Future priorities include harmonized diagnostic standards, validation of non-invasive surveillance, cross-clade vaccine trials, host-immunogenetic research, and coordinated international governance to protect captive and wild psittacine populations.

Keywords: beak and feather disease virus, biosecurity, circovirus, conservation, diagnostics, molecular epidemiology, psittacine beak and feather disease, vaccination.