Factors associated with avian influenza infections in indoor commercial poultry farm settings: A systematic review.

Avian influenza (AI) poses a significant threat to animal and human health, as well as to the poultry industry, with demonstrably pandemic potential. Intensive farming has been associated with conditions that may facilitate the emergence and spread of AI viruses with pandemic potential. To assess the risk and protective factors associated with AI infections in poultry within intensive production systems, a systematic literature review was conducted. Databases including Embase, PubMed/Medline, the Health Management Information Consortium, and Global Health were searched for publications from 2003 to 2023, with additional grey literature included. A total of 127 full-text studies were reviewed by two independent researchers, resulting in 27 studies being included. Quality appraisal of the included studies was performed using the Critical Appraisal Skills Programme and the Joanna Briggs Institute checklists, leading to the exclusion of four studies due to low quality. Ultimately, 23 studies were included in the final analysis. Study characteristics, as well as risk and protective factors were extracted, with most factors being related to the introduction of AI into commercial poultry farms. Biosecurity measures emerged as the most significant protective factor against AI. Environmental factors and the production system adopted also influenced a farm's risk of AI infections. Given AI's detrimental effect on ecosystems, economies, international trade, and both human and animal health, enhancing husbandry and biosecurity practices on commercial poultry farms is crucial to safeguard animal welfare, promote sustainable poultry production, and manage the risk of emerging pandemic AI strains.