While scientists work on ways to stop E. coli 0157:H7 contamination of food products, it's easy to protect yourself.
"It's easy to eliminate the risk of contaminated hamburgers," said Mike Doyle, director of the University of Georgia Center for Food Safety and Quality Enhancement. "Just make sure you cook them properly."
UGA studies have shown that heating ground beef to 155 degrees Fahrenheit for 15 seconds will kill E. coli bacteria, Doyle said.
"The U.S. Department of Agriculture recommends cooking ground beef to 160 degrees," he said. "That allows for a margin of safety."
The latest USDA recommendations call for using a meat thermometer to check the internal temperature. And Doyle concurs that it's the only perfectly safe way to check.
"I continue to tell people to cook a hamburger until it's no longer red inside and the juices run gray or are no longer pink," he said. "But there is evidence that color isn't always reliable."
Checking hamburger patties with most meat thermometers is hard, if not impossible. "There are some new ones that cost about $10," he said. "They're thinner and can be inserted into a patty easier than standard meat thermometers."
But Doyle said just getting a 160-degree reading isn't a perfect indicator. "There can be a 10-degree variation from one spot to another in some hamburgers," he said. "The coldest spot isn't always the center."
E. coli 0157:H7 causes severe stomach cramps and diarrhea which oftens turns bloody after two or three days. The symptoms usually go away by themselves after six to eight days.
In a small number of people, most often children, the E. coli strain can cause a rare but serious problem called hemolytic uremic syndrome, which can lead to kidney failure and death.
Young children, the elderly and people with compromised immune systems are the most susceptible to foodborne illness.