BRITAIN VACCINATING CHICKENS FOR SALMONELLA

Vaccine for hens against salmonella, the bacteria that tainted eggs and caused thousands of cases of illness.
Room for Debate
Why Eggs Became a Hazard
The American food safety system has failed to eliminate the threat of salmonella. Why?

Lohmann Animal Health International, in Winslow, Maine, is one of three companies that make the vaccine in the United States.
But when American regulators created new egg safety rules that went into effect last month, they declared that there was not enough evidence to conclude that vaccinating hens against salmonella would prevent people from getting sick. The Food and Drug Administration decided not to mandate vaccination of hens — a precaution that would cost less than a penny per a dozen eggs.

Now, consumers have been shaken by one of the largest egg recalls ever, involving nearly 550 million eggs from two Iowa producers, after a nationwide outbreak of thousands of cases of salmonella was traced to eggs contaminated with the bacteria.

The F.D.A. has said that if its egg safety rules had gone into effect earlier, the crisis might have been averted. Those rules include regular testing for contamination, cleanliness standards for henhouses and refrigeration requirements, all of which experts say are necessary.

However, many industry experts say the absence of mandatory vaccination greatly weakens the F.D.A. rules, depriving them of a crucial step that could prevent future outbreaks.

Salmonella bacteria is passed from infected hens to the interior of eggs when they are being formed. The salmonella vaccines work both by reducing the number of hens that get infected and by making it more difficult for salmonella bacteria to pass through to the eggs.

“They are the only thing I’m aware of that really controls the problem from the inside out, at the source,” said Ronald Plylar, the former president of a company that developed an early salmonella vaccine.

Many people in the American egg industry say they believe that the current outbreak and recall will tip the balance and force nearly all producers in the United States to begin vaccinating hens to reassure consumers.

The F.D.A. said it considered mandatory vaccination very seriously. “We didn’t believe that, based on the data we had, there was sufficient scientific evidence for us to require it,” said Dr. Nega Beru, director of the agency’s Office of Food Safety.

However, Dr. Beru says that the new rules encourage producers to vaccinate if they think it will help fight salmonella.

Another F.D.A. food safety official, Nancy S. Bufano, said that despite the success of vaccination in Britain, the agency thought that because the vaccines used in the two countries were not identical, it made comparisons difficult.

Vaccine company executives, however, said the differences were minor and the drugs used in both countries were equally effective.

The drop in salmonella infections in Britain was stunning.

In 1997, there were 14,771 reported cases in England and Wales of the most common type of the bacteria, a strain known as Salmonella Enteritidis PT4. Vaccine trials began that year, and the next year, egg producers began vaccinating in large numbers.

The number of human illnesses has dropped almost every year since then. Last year, according to data from the Health Protection Agency of England and Wales, there were just 581 cases, a drop of 96 percent from 1997.

“We have pretty much eliminated salmonella as a human problem in the U.K.,” said Amanda Cryer, director of the British Egg Information Service, an industry group.

The F.D.A. estimates that each year, 142,000 illnesses in the United States are caused by consuming eggs contaminated with the most common type of salmonella. It has said the new rules would cut that by more than half. People who eat bad eggs that have not been cooked thoroughly to kill the bacteria can get diarrhea and cramps. Rare cases can be fatal.

There are no laws mandating vaccination in Britain. But it is required, along with other safety measures, if farmers want to place an industry-sponsored red lion stamp on their eggs, which shows they have met basic standards. The country’s major supermarkets buy only eggs with the lion seal, so vaccination is practiced by 90 percent of egg producers, according to Ms. Cryer.

Thomas Humphrey, a food safety professor at the University of Liverpool, said that producers in the United Kingdom turned to vaccination after other measures, similar to those now required by the F.D.A., failed to show significant results.

One-half to two-thirds of American farmers already inoculate their flocks, according to industry estimates, and that number is likely to increase. While the new federal rules do not require vaccination, they do require testing for salmonella. If henhouses are found to be contaminated, then eggs must be tested. If eggs are tainted, then they would have to be broken and pasteurized, which would mean producers would get much less money for their eggs.