Food poisoning sickens millions of Americans each year, and most outbreaks are caused by salmonella-tainted foods or norovirus, federal health officials report.
Salmonella-contaminated eggs alone accounted for 2,231 illnesses in 2009-2010, according to researchers from the U.S. Centers for Disease Control and Prevention who set out to identify the specific pathogens responsible for widespread foodborne illnesses.
"CDC estimates that one in six Americans get sick from a foodborne illness each year," said lead author L. Hannah Gould, a senior epidemiologist at CDC's National Center for Emerging and Zoonotic Infectious Diseases.
More than 1,500 foodborne-disease outbreaks were reported in 2009-2010, involving nearly 29,500 illnesses, 1,200 hospitalizations and 23 deaths, according to the CDC.
Besides salmonella in eggs, common causes of outbreaks included E. coli O157 in beef and Campylobacter in unpasteurized dairy products. Besides salmonella-contaminated eggs, outbreaks were also traced to salmonella in sprouts and vegetables, such as tomatoes and peppers, the agency said.
More than 40 outbreaks resulted in product recalls, according to the CDC's Morbidity and Mortality Weekly Report.
However, outbreaks account for only 5 percent to 10 percent of foodborne illnesses, Gould said. And not all outbreaks get reported, she noted.
Both salmonella and norovirus, also called cruise-ship flu, cause serious gastrointestinal problems.
Marc Siegel, M.D., an associate professor of medicine at NYU Langone Medical Center in New York City, said foodborne illness is "epidemic" in the United States. "There is a lack of scrutiny of food products," he said.
Contamination can occur at any step along the food chain, from farm to fork, Gould said.
"Everyone has a role in preventing foodborne illness, starting at the farm to processing to restaurants and at the home," Gould said.
"Most foodborne illness is preventable if people follow the right steps," she added. The keys to prevention include hand washing, proper storage and preparation. Clean foods, keep meat and produce separate and cook foods thoroughly, Gould said. Also, keep produce, meats, and eggs refrigerated.
Of more than 700 outbreaks attributed to a single source, 48 percent were traced to food eaten in a restaurant or deli, and 21 percent were caused by food eaten at home.
If you're eating out, Gould suggests checking the restaurant's health inspection score. "Don't eat there if the score is low," she said.
Dr. Siegel said much of the contamination occurs at the farm and in processing. Farming practices are to blame in many cases, he said.
Chickens are raised in their own feces, which is the source for most Salmonella, and cattle are fed grain, which makes their stomachs a breeding ground for E. coli, he said.
"If we improve the conditions chickens are raised in, and if we start feeding cows grass instead of grain, much of the initial contamination could be stopped," Dr. Siegel said.