Study validates disc diffusion method for Salmonella vaccine DIVA

A new paper in Veterinary Sciences reports that a disc diffusion method can reliably distinguish a live bivalent Salmonella vaccine strain from field strains across multiple suppliers, addressing a practical diagnostic problem in vaccinated poultry flocks. The study focuses on differentiation of vaccine-derived Salmonella Enteritidis and Salmonella Typhimurium from pathogenic field isolates, a key issue when live vaccines are used in breeding and laying hens. That matters because licensed live poultry Salmonella vaccines are designed to support control programs, but they can complicate surveillance if labs can't quickly tell vaccine strains from true field infections. WOAH guidance explicitly says that, when live vaccines are used, field and vaccine strains should be easily differentiated in the laboratory. (woah.org)

Why it matters: For veterinary professionals working in poultry health, food safety, and flock monitoring, a validated low-complexity disc diffusion approach could make confirmatory testing more accessible than molecular methods alone, especially across different lab suppliers and routine workflows. Reliable differentiation helps avoid misclassifying vaccinated flocks as infected, supports faster risk assessment, and may reduce unnecessary escalation, movement restrictions, or other control actions tied to positive Salmonella findings. That fits with broader international guidance that vaccination should be part of an overall control program, not a substitute for surveillance, biosecurity, and veterinary oversight. (woah.org)

What to watch: Watch for whether the method is adopted in routine poultry diagnostic protocols, referenced in product support materials, or compared head-to-head with PCR-based DIVA approaches in future validation work. (pubmed.ncbi.nlm.nih.gov)