Count every chicken: Salmonella risk research 

Raw poultry is one of the main causes of salmonella poisoning, which affects thousands of people every year. A study from the University of Illinois shows that few products with high levels of very virulent Salmonella strains are responsible for most of the illnesses from raw chicken parts. The researchers suggest regulation efforts should focus on detecting and preventing those types of high-risk contamination.

Study co-author Matt Stasiewicz, an associate professor in the Department of Food Science and Human Nutrition (FSHN), said: “Over the last 20 years, the poultry industry has done a really good job of lowering the frequency of Salmonella in poultry. However, the number of people who are getting sick from these pathogens hasn’t declined. The U.S. Department of Agriculture is considering changes to how they regulate Salmonella based on level and serotype, and our research supports those efforts.”

There are over 2600 serotypes, or sub-groups, of Salmonella bacteria and they differ in their capacity to make people sick. Salmonella Kentucky is one of the most common serotypes in US chicken, but it is less likely to cause human illnesses compared with three more virulent strains linked to multiple outbreaks of salmonellosis.

The researchers wanted to assess the public health risk from Salmonella contamination of chicken parts, comparing the impact of high- and low-virulence serotypes at different levels.

Lead author Minho Kim said: “We applied a mathematical method called Quantitative Microbial Risk Assessment, using datasets on contamination from the USDA Food Safety and Inspection Service as input. We set different levels and serotype thresholds to estimate the risk of getting ill from each of them.”

The baseline calculations yielded an estimate of about two salmonellosis cases per 1 million servings of chicken consumed. In all the scenarios, risk was concentrated in a few products with high levels of highly virulent serotypes. Less than 1% of illnesses were attributed to Salmonella Kentucky, while 69–83% of illnesses were attributed to products with high levels of Enteritidis, Infantis or Typhimurium serotypes. These findings are consistent with what seems likely to be the proposed changes in regulations, the researchers stated.

The next step is to figure out how to specifically target those virulent strains. Kim and Stasiewicz suggest possible approaches such as using statistical processing control to monitor Salmonella, a test-and-hold procedure for batches of products or vaccinating chickens against the high-virulence serotypes.

However, they emphasise that their research focuses on estimating the risk, and it is up to the poultry industry — which knows best how to improve its processes — to find strategies to manage it.

The paper, ‘Risk Assessment Predicts Most of the Salmonellosis Risk in Raw Chicken Parts is Concentrated in Those Few Products with High Levels of High-Virulence Serotypes of Salmonella’, is published in the Journal of Food Protection.

Image credit: iStock.com/Manjurul