Estimation of the impact of vaccination on faecal shedding, organ and egg contamination for Salmonella Enteritidis, Typhiumurium and monophasic Salmonella Typhimurium.

In this study, the effectiveness of four vaccination programmes currently in use in the UK poultry industry was evaluated against challenge with one SE strain, one ST strain and 2 monophasic ST strains. A Bayesian model was used to estimate the impact of vaccination on the rate of faecal shedding, and on egg contamination. For the majority of vaccine/challenge strain combinations, there was little or no effect of vaccination on the proportion of birds shedding Salmonella for either biphasic or monophasic strains. However, vaccination was effective at reducing egg contamination. A significantly lower proportion of eggshells were positive for the vaccinated birds compared to non-vaccinated birds, including the mST strains (vaccination resulted in a 55 and 21% reduction for the 2 mST strains). Calculated across all strains, the estimated rate of positive egg contents was lower in vaccinated birds (Bayesian median was 0.13% for vaccinated versus 0.27% for non-vaccinated birds). For both vaccinated and unvaccinated birds, there was also an apparent difference in the proportion of organs positive between strains, with the SE strain resulting in a lower proportion of positive organs at post-mortem examination compared to the other strains. PMID: 24617816 [PubMed - as supplied by publisher]
Source: Avian Pathology - Category: Pathology Authors: Tags: Avian Pathol Source Type: research