Chasing Salmonella Typhimurium in free range egg production system

Area of Science:

• Veterinary Microbiology
• Food Safety
• Ecology

Background:

• Free range egg production is increasing globally.
• Understanding Salmonella ecology in these systems is crucial for public health.

Purpose of the Study:

• To investigate Salmonella Typhimurium and species shedding and ecology in free range layers, wild birds, and foxes.
• To assess the role of environmental factors and seasons on Salmonella prevalence.
• To determine potential links between corticosterone levels and Salmonella shedding.

Main Methods:

• Seasonal sampling of free range layer flocks, wild birds, and foxes.
• Salmonella isolation and identification.
• Multilocus Variable Number Tandem Repeat Analysis (MLVA) for Salmonella Typhimurium typing.
• Faecal corticosterone analysis.

Main Results:

• Significantly higher Salmonella shedding observed during summer.
• Highest Salmonella prevalence detected in dust within the sheds.
• Faecal corticosterone levels peaked in spring, with no direct correlation to Salmonella shedding.
• MLVA profiles of Salmonella Typhimurium from foxes and wild birds matched those from the layer flock and human cases.

Conclusions:

• Wild birds and foxes are significant reservoirs for Salmonella Typhimurium, influencing farm ecology and food safety.
• Environmental factors may contribute to the evolution of Salmonella Typhimurium in free range settings.
• Seasonal variations impact Salmonella shedding dynamics in free range poultry production.