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New Vaccine To Fight Salmonella in Eggs

Developing an oil emulsion vaccine to reduce the possibility of Salmonella enteritidis entering chicken eggs is the aim of scientists at the Agricultural Research Service's Southeast Poultry Research Laboratory in Athens, Ga. Immunologist Peter Holt, retired veterinarian Henry Stone and immunochemist Cam Greene have developed an oil emulsion vaccine of inactivated S. enteritidis that protected hens exposed to the organism.

Hens infected with Salmonella can transmit the organism into their eggs. People who eat infected eggs can get salmonellosis, a disease characterized by nausea, vomiting and severe diarrhea.

In studies at Athens, birds were vaccinated twice and then exposed to S. enteritidis. The new vaccine reduced S. enteritidis shedding in the birds' feces by 10 to 40 percent. A patent for the vaccine has been filed and is available for licensing.

The experimental oil emulsion vaccine is more effective than commercial vaccines because it boosts levels of antibodies that the hens produce to fight the infection, reducing S. enteritidis inside their intestines. This, in turn, decreases the chance that the bacterium will spread further through the birds' bodies, or that it will be shed in their feces.

An improved vaccine that reduces Salmonella shedding would be helpful to the poultry industry, since this is the primary method by which Salmonella infection spreads through a flock. Vaccinating poultry flocks against Salmonella is an important practice within the industry today. Approximately 25 million doses of S. enteritidis vaccine are used annually in U.S. poultry, while 50 to 75 million doses are used worldwide.

More information on the research is available in the May 2003 issue of Agricultural Research magazine.

ARS is the U.S. Department of Agriculture's chief scientific research agency.