Salmonella enteritidis.  Click the image for additional information about it.

Seeing Salmonella Move Through Pigs

Imagine being able to photograph a salmonella infection as it moves through a live pig and show the process as patches of colors. That's what's being proposed by Donald C. Lay, research leader at the Agricultural Research Service's Livestock Behavior Research Unit in West Lafayette, Ind., and Scott T. Willard of Mississippi State University. Willard is an expert in biophotonics, a new technology that uses light to mark molecular changes.

About two million salmonella cases are found in livestock in the United States each year, costing an average $1.4 billion. Certain swine seem prone to shedding Salmonella bacteria in manure when stressed by the transport and mixing with different herds that's associated with going to market. Scientists don't know how bacteria migrate through an animal's body, including where they might "hide" and what causes them to be suddenly shed. These gaps are largely due to an inability to follow the progression of infection in live animals.

Lay and Willard have shown they can treat bacteria to give off light, making it possible to track infections in living piglets and through tissues of adult pigs after slaughter. Now they've received a U.S. Department of Agriculture grant to further pursue the work. Their goal: to adapt the technique so cameras can see through the denser mass of live, 250-pound, market-ready pigs, which is more difficult than seeing through five-pound piglets.

Lay and Willard will research ways to improve swine management by identifying animals that are more susceptible to infection, and by designing techniques to prevent those swine from spreading infection to their herd mates.

ARS is the USDA's chief scientific research agency.