Research identifies distinct transmission pathways for Salmonella serovars throughout broiler production systems

A study of six US broiler complexes found that approximately one-quarter of pre-placement environments tested positive for Salmonella, increasing to 100% within seven days of chick placement, indicating rapid colonization dynamics. Different Salmonella serovars showed distinct transmission patterns, with Enteritidis and Mbandaka indicating vertical transmission from breeders and hatcheries, while Infantis appeared only on broiler farms suggesting horizontal transmission and persistence between flocks. Understanding these serovar-specific transmission differences can enable more targeted control strategies to improve poultry food safety and reduce the estimated 20% of salmonellosis cases linked to contaminated chicken consumption.

Researchers tracked Salmonella contamination across the entire broiler production chain—from breeding facilities through hatcheries to farm environments—across six complexes in four states. The findings revealed a dramatic shift: while only about 25% of broiler houses tested positive before chicks arrived, this jumped to complete contamination within a week. The study employed molecular techniques to identify which bacterial strains originated from earlier production stages versus those already present on farms.

The research distinguished between two contamination routes. Certain serovars, including Enteritidis and Mbandaka, traced back to breeder flocks and hatcheries, suggesting vertical transmission through the supply chain. In contrast, Infantis appeared exclusively on broiler farms, indicating it persists in farm environments between successive flocks and spreads horizontally among birds housed together.