Immunoglobulin-Y in Infectious Disease Diagnostics: The Ethical, Sustainability and Conditions Does It Outperform Conventional Antibodies.

Infectious diseases remain a major global health challenge, and effective control depends on early and accurate diagnosis. However, conventional immunodiagnostic platforms rely heavily on mammalian antibodies, which may present limitations related to animal welfare, production, and nonspecific immunological interactions. Immunoglobulin Y (IgY), isolated from the yolk of eggs collected non-invasively from immunized hens, has emerged as a potential alternative, although its advantages over conventional mammalian antibodies appear to be context-dependent rather than universal. This narrative review synthesizes current evidence on IgY production, diagnostic performance, comparative advantages and limitations, and ethical and sustainability considerations. A structured literature search of PubMed and Scopus covering January 2016 to February 2026 identified 66 records. Of these, 25 articles underwent full-text eligibility assessment, and 17 studies met the inclusion criteria and were included in the qualitative synthesis. Additional supporting literature identified through hand-searching was used for mechanistic and contextual interpretation but was not counted among the 17 included studies. Across the diagnostic studies, IgY demonstrated favorable performance in selected immunoassay platforms, particularly where reduced interaction with mammalian Fc receptors, rheumatoid factor, or complement may decrease nonspecific interference. High diagnostic performance was reported for applications including bovine coronavirus detection (97.7% sensitivity and 98.2% specificity) and SARS-CoV-2 detection (>90% sensitivity and specificity). However, IgY did not consistently outperform mammalian antibodies across all applications, with limitations observed in free-solution turbidimetric assays, selected in vivo models, and certain engineered antibody formats. Two included studies addressed ethical and sustainability considerations, with quantitative sustainability assessment indicating advantages for IgY-based approaches, although the evidence remains limited. Overall, IgY represents a promising but context-dependent alternative to conventional antibodies. Further head-to-head comparative studies, standardized production and validation protocols, and larger-scale clinical evaluation are required to define the diagnostic settings in which IgY provides a meaningful advantage.