“Our product has Salmonella on it, and some people will get sick. We want to reduce the risk of people getting sick,” said Dr. Randy Singer, epidemiologist, departments of veterinary and biomedical sciences, University of Minnesota.

Singer spoke at the Poultry Federation Salmonella Summit, which was held at a casino in West Siloam Springs, Okla. He asked, “Why do regulators continue to focus on prevalence? That isn't a good indicator of risk. We should be focused on [Salmonella] loads, not prevalence.”

A casino provided an appropriate backdrop for a discussion of risk assessment and calculating the odds of keeping people healthy. Singer said that it absolutely matters which strain of Salmonella is present on a food item when considering risk of someone getting sick. He said that there is a dose-related effect to getting sick. “You get sick from a food item with an infective dose, not from one that is ‘positive’ for Salmonella.” He estimated that an infective dose would tend to be a minimum of 1,000 to 10,000 cells of Salmonella and that one cell would not make someone sick.

Singer said that the USDA is using models to estimate risk that use prevalence of Salmonella and not the infective dose. If you take real data and plug the data into the models, they don’t work. “The models aren't working,” he said. "Prevalence is not an indicator of risk." Singer said that the USDA calls for Salmonella interventions to provide log reductions of Salmonella, and that this recognizes that load is part of risk not prevalence.

Correlating the farm with the plant

Singer and other researchers wanted to find a simple measurement that could be taken at a broiler farm before the flock was brought to slaughter that would correlate well with post-chill Salmonella samples for the flock. They found that “boot sock” environmental samples taken in the broiler house a week of two prior to slaughter correlated fairly well with post-chill Salmonella and Campylobacter samples for the flocks when they were marketed. A “boot sock” sample is just a sock worn over a boot while you walk through the broiler house. In their studies, Singer said that they walked in between the feed and water line in the houses.

If you introduce live side Salmonella interventions, Singer continued, you can predict the impact on post chill product samples by doing boot sock tests in the houses. This allows for quicker feedback on what interventions are working.

Singer said that the poultry industry needs to attack those strains of Salmonella that are causing problems to animal health and human health.