Study Shows Salmonella Is the Most Commonly Reported Food-borne Illness in U.S.
By Brenda Goodman
WebMD Health News
Latest Infectious Disease News
Reviewed by Louise Chang, MD
Dec. 15, 2010 -- The first government estimates of food-borne illnesses in a decade find that one in six Americans gets sick, 128,000 people are hospitalized, and 3,000 people die each year after eating tainted food.
"These illnesses are associated with billions in health care costs and also have a substantial human cost in severe illnesses and in some cases, long-term health effects that linger after the initial illness subsides," says Christopher Braden, MD, acting director of the CDC's Division of Foodborne, Waterborne and Environmental Diseases. "We need to do more to lower the impact of these diseases in the United States."
Previous estimates, released in 1999, showed that 76 million, or one in four Americans, got sick each year, 325,000 people were hospitalized, and 5,000 people died because of food poisoning.
Food Supply Safety
Experts caution, however, that the new numbers, which were released by the CDC on Wednesday, probably reflect the availability of more and better information about the problem and are not necessarily an indication that the food supply has become safer.
"Just because we have more precise data that allows us a better estimate, that doesn't mean that food-borne illnesses have gone down that much," says Kirk E. Smith, DVM, PhD, supervisor of the Foodborne Disease Unit of the Minnesota Department of Health, which has been one of the most aggressive in identifying outbreaks of food-borne illnesses in the U.S.
Smith says that clear inroads have been made against certain pathogens.
"E. coli 0157 has gone down quite a bit, presumably because of a lot of the work that industry and regulators are doing in beef processing plants. Listeria has gone down -- probably the same story there," he says.
But experts also lamented that almost no progress had been made against salmonella, the most commonly diagnosed and reported food-borne illness, according to preliminary data from the CDC's 2010 FoodNet surveillance report.
Salmonella accounted for 28% of deaths and about 35% of hospitalizations caused by known pathogens.
"While rates of campylobacter, E. coli, and listeria have notably declined, salmonella has not," says Craig W. Hedberg, PhD, a professor of environmental health sciences in the University of Minnesota School of Public Health. "The biology of salmonella is complex, and there are many sources and transmission routes that we don't understand well. I think that understanding and preventing salmonella should be the major focus of food safety activities for the next few years."
Salmonella bacteria were responsible for a massive recall of eggs in 2010 and of peanut butter in 2009 -- outbreaks that sickened hundreds of people.
Why the Numbers Went Down
According to the CDC, the new estimates are more precise than the 1999 numbers since they were derived from a greater volume of data and used better definitions of food-borne illness.
The new data include surveys of more than 48,000 people, five times as many people as were included in the 1999 report.
The new numbers also rely heavily on estimates of food poisoning caused by so-called unspecified agents. These were cases of gastrointestinal illness that couldn't be tied to a known pathogen but that seemed to have all the hallmarks of a food-borne illness: cases of vomiting or diarrhea that lasted more than a day but were not associated with cough or sore throat.
"We took the number of cases of acute gastroenteritis illnesses and subtracted the ones we knew about, that is the number caused by known pathogens, and arrived at an estimate of unspecified agents," says Elaine Scallan, PhD, an assistant professor at the Colorado School of Public Health in Aurora, Colo., who was the lead author of both of the new studies.
Additionally, the new numbers discount cases of food poisoning acquired during international travel, whereas the 1999 numbers included travel-related illnesses.
While the new estimates are more refined, experts say they could still be viewed as conservative.
"Not everybody who becomes ill sees their doctor, and even when they do, not everybody has tests done to determine what's causing the illness," says Braden. "That is taken into account in the estimates. However, one could look at the methods for these estimates and determine that our methods were quite conservative and in reality, for a number of these pathogens it could be more than we've estimated."
SOURCES: Christopher Braden, MD, acting director, Division of Foodborne, Waterborne and Environmental Diseases, CDC.Elaine Scallan, assistant professor, Colorado School of Public Health.Scallan, E. Emerging Infectious Diseases, January 2011.Kirk E. Smith, DVM, PhD, supervisor of the Foodborne Disease Unit, Minnesota Department of Health.Craig W. Hedberg, PhD, professor of environmental health sciences, University of Minnesota School of Public Health.Mead, P. Emerging Infectious Diseases, September-October 1999.
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