Assessing biosecurity practices, movements and densities of poultry sites across Belgium, resulting in different farm risk-groups for infectious disease introduction and spread

The existing diversity within poultry systems affects the potential risk of infectious disease introduction and spread. Population data on the level of biosecurity and between-farm contacts is scarce, despite its importance for identifying possible routes of disease transmission. A study was carried out in Belgium to investigate and differentiate professional and hobby poultry sites based on their biosecurity levels and farm movements. Questionnaire data from a total of 37 professional poultry farms, 19 hatcheries and 286 hobby poultry sites were analyzed using a combination of a linear scoring system, a Categorical principal component analysis (CATPCA) and a Two-Step cluster analysis (TSCA). In general, the level of biosecurity was lower in hobby poultry flocks, mainly due to the poor confinement against the outdoor environment and the poor infrastructural hygiene. Most Belgian professional poultry farms and hatcheries had an acceptable level of adoption of standard biosecurity practices, however less attention was given to the way transportation vehicles and employers were brought onto farms and professional visitors welcomed. Considerable variation in the movements and in the structure of the networks arising from these movements was found. Movement frequencies were higher at professional farms compared to hobby farms. Results showed that multiple category farming systems had the highest total movement frequencies. Monthly frequencies of professional visits often exceeded those of poultry and egg movements. Professional and hobby poultry sites were also connected, but movements of poultry and eggs were found only to occur from professional to hobby sites. However, hobby poultry keepers were personally purchasing the poultry and eggs on the professional poultry sites. Six groups of poultry sites were differentiated, which are interpreted as very low to very high risk groups, based on the potential of infectious disease introduction and spread.