Chris Tuggle and colleagues at Iowa State University are looking at developing new ways to identify animals harboring salmonella.

“We are developing a blood test to identify animals that shed the least amount of salmonella into the environment,” Tuggle says.

Pigs can become infected and carry salmonella without showing any symptoms. Infected animals shed the bacteria in their manure, which often is used to fertilize crops.

Tuggle, professor of animal science, and his research team examine the genetic makeup of pigs, and sample blood and fecal matter for evidence of salmonella. Then they look for linkages between the expression of genes in blood and the level of salmonella shed by the pig.

Their work has yielded a gene expression signature, or classifier, that can predict the level to which an animal will carry the suspect gene.

“Salmonella is present in more than half of U.S. swine herds. It results in more than $100 million in annual production losses,” Tuggle says. “But more importantly, what’s driving this research is the food safety issue. There are 1.4 million cases of salmonellosis in the United States annually. Our results have the potential to not only decrease salmonella contamination in pork, but also on sprouts, peppers or any other vegetable crop for which manure is used as fertilizer.”

If genetic selection can be used to prevent the occurrence or spread of salmonella in swine herds, it can reduce reliance on antibiotics.

“It takes a collaborative effort to approach this,” Tuggle says. “I work with animal scientists, statisticians, computer scientists and immunologists.”

The research report on salmonella appeared in the winter 2011 edition of the Food Safety Consortium newsletter. The publication is a production of its three members, University of Arkansas, Iowa State University and Kansas State University.