Last week, the Centers for Disease Control issued an advisory about beef products from JBS Swift Beef Company that may be contaminated with E. coli O157:H7.

This week, the U.S. Food and Drug Administration announced that a sample of prepackaged Nestle Toll House refrigerated cookie dough yielded E. coli O157:H7.

O157:H7 is a dangerous strain of E. coli. When ingested by humans, it can cause bloody diarrhea, and in some people, especially children, a potentially deadly disease called hemolytic uremic syndrome,

But there is some good news. USDA has issued a conditional license to Epitopix LLC, a Minnesota veterinary pharmaceutical company, to market Escherichia coli Bacterial Extract, a vaccine that can stop O157:H7 before it makes its way into the food chain, according to an article in today's San Francisco Chronicle. The vaccine works by preventing the bacteria, which are not harmful to cattle, from getting to the iron in a cow's intestines.

"The vaccine is potentially very exciting," the story quoted Michele Jay-Russell, a UC Davis epidemiologist. "Being able to reduce the bacteria will not only have an effect on the beef industry, but on the environment."

Jay-Russell manages a team of scientists investigating the 2006 E. coli outbreak in bagged spinach that killed three people and sickened 205 nationwide. In that incident, scientists have narrowed down the most likely cause of the contamination to either wild pigs or to a cattle herd a mile away from the spinach farm.

"That's why the vaccine is one more intervention to have," she was quoted. But, she cautioned, "It's not the end-all and be-all, and it doesn't mean everyone can relax."