Assessing the potential transmission of major Salmonella serotypes from
chicken feed to humans in Belgium based on the national monitoring
program (2010-2017)
Abstract
Vertical and horizontal transmissions of Salmonella spp. along the food
chain (FC) have been reported to play an important role in the
contamination of foodstuffs and of humans. This study aims first to
clarify to what extend some selected major Salmonella serotypes are
represented along the chicken FC and potentially transmitted from feed
to humans. Then to discuss if the sampling results of the Belgian
National Salmonella monitoring program may be considered as proxy to
predict possible dominant serotypes and trends in humans. By using
results of this programme, this study tried to highlight statistically
significant differences in yearly prevalences between broilers exit
status and other matrices (e.g. feed, other chicken categories,
foodstuffs). Then to show up statistically significant changes from year
to year prevalences in broilers exit status and to look if these changes
can also be observed in the other matrices. Results have showed
significant differences in yearly prevalences. They also pinpointed that
the prevalence for the same serotypes could significantly vary from year
to year in broilers exit status but this variation was inconsistently
observed in the other matrices. These observations do not support the
assumption of significant vertical and horizontal bacterial transmission
along the chicken FC. Results in the national program cannot be
considered as proxy. Determining the contribution of contaminated animal
feed to human illness is challenging as the interplay of many factors
makes it difficult. Coupling the actual programme with network analysis,
source attribution and genome sequencing would be a way to explore
deeper the spread of Salmonella serotypes along the FC. Belgium has put
efforts to decrease Salmonella Enteritidis and Salmonella Typhimurium
prevalence along the FC, but attention should be also paid to other
pathogens that could fill the vacant niche left as Salmonella infantis
which prevalence has been increasing in some matrices.