By Sean Henahan, Access Excellence

Now, researchers at Iowa State University have developed a poultry vaccine that they believe could reduce the incidence of salmonella-tainted eggs. The experiemental vaccine prevents hens from spreading salmonella to their eggs. It also significantly reduces the likelihood of the bacteria spreading to other chickens through feces, the researchers report.

The vaccine targets bacteria called Salmonella Enteritidis, organisms which cause food poisoning in humans called salmonellosis. The bacteria are found in the intestinal tracts of animals and humans and are easily spread. Thousands of people are hospitalized in the US each year with salmonella infection which can be fatal. About half of these cases are attributed to infected chicken eggs, according to ISU veterinary microbiologist Theodore Kramer

Kramer developed the vaccine using technology similar to what he and another ISU researcher used five years ago to create a swine salmonellosis vaccine. Both vaccines use live salmonella bacteria that have been stripped of their disease-causing capabilities. The new vaccine is administered to hens in their drinking water.

The vaccine could benefit egg producers around the world because salmonella-contaminated eggs are a global problem. Egg-borne human salmonellosis is most common in the United States along the East Coast.

"Salmonella costs the United States $2.5 billion a year," Kramer notes.

Humans who contract salmonellosis from eggs usually do so by eating products such as ice cream, mayonnaise or salad dressing made with contaminated eggs. Salmonellosis symptoms include attacks of abdominal cramps, nausea, vomiting and diarrhea. The attacks may be more serious for infants, pregnant women, the elderly and the ill.

"The effects of salmonellosis can be far-ranging," Kramer said. "A contaminated food product produced in a large quantity and distributed widely can cause illness in several states."

Salmonellosis is normally not a health problem for consumers who properly store and cook their eggs, Kramer added.

Kramer said it is important to keep chicken flocks from being infected with Salmonella Enteritidis. The bacteria are difficult to detect in chickens. Infected hens usually do not appear ill and current tests for the bacteria are time consuming and costly, Kramer explained.

"In a unit of 10,000 hens, it would be difficult to test every bird," Kramer said. "If salmonellosis is found, about all the producer can do is destroy all of the hens. That can be financially ruinous to the producer."

The vaccine still requires USDA approval before it can be used by egg producers.