Data on gastrointestinal illnesses in the U.S. indicate viruses, bacteria, and parasites in food kill about 3,000 people yearly and sicken about 48 million more.
The Centers for Disease Control and Prevention published in mid-December two reports that together indicate about one-sixth of people in the U.S. suffer foodborne illnesses each year. About 9.4 million of them are sickened by one or more of 31 major pathogens. The remaining illnesses are attributed to "unspecified agents," including agents for which insufficient data are available to directly attribute illness, agents suspected but not known as causes of illness, and unknown causes.
Foodborne illnesses are connected with about 3,000 deaths and about 128,000 hospitalizations yearly, the data indicate.
"This research is very important because it provides a window into which of the 31 known foodborne pathogens are causing most harm to the public and which cause most severe illness," Christopher R. Braden, MD, director of the CDC's Division of Foodborne, Waterborne, and Environmental Diseases, said. "By knowing this, CDC and our regulatory partners can better target those pathogens so we can better help to protect the nation's food supply."
The reports, "Foodborne Illness Acquired in the United States—Major Pathogens" and "Foodborne Illness Acquired in the United States—Unspecified Agents," were released online in December and were published this January in the CDC journal Emerging Infectious Diseases.
The next most recent comprehensive estimates were also provided in Emerging Infectious Diseases through the 1999 report "Food-Related Illness and Death in the United States," which stated that foodborne illnesses were believed to be connected with about 76 million illnesses, 325,000 hospitalizations, and 5,000 deaths annually. Those figures include illnesses caused by known and unknown agents.
Dr. Braden stressed during a conference call with news media that data sources and collection methods improved between production of the 1999 and 2011 reports, and the two reports cannot be compared to evaluate trends. The information in the 2011 report is believed to be more precise.
Dr. Braden noted that data collected through FoodNet, a collaborative disease surveillance system involving emerging infections program sites in 10 states, the CDC, the Department of Agriculture, and the Food and Drug Administration, have separately indicated that the number of foodborne illnesses caused by major pathogens tracked in that system decreased about 20 percent in the past 10 years.
Small number of pathogens caused most harm
The 2011 report on known agents indicates about 58 percent of the 9.4 million foodborne illnesses that occur each year are caused by norovirus, while nontyphoidal Salmonella spp account for 11 percent, Clostridium perfringens accounts for 10 percent, and Campylobacter spp account for 9 percent.
However, nontyphoidal Salmonella spp are believed to be responsible for 35 percent of hospitalizations related to foodborne illness, norovirus for 26 percent, Campylobacter spp for 15 percent, and T gondii for 8 percent. Nontyphoidal Salmonella spp are also believed to account for 28 percent of deaths, while T gondii account for 24 percent, Listeria monocytogenes for 19 percent, and norovirus for 11 percent.
Dr. Braden said the number of illnesses, while lower than previously estimated, illustrates the need for an increased commitment to reducing the burden of foodborne illnesses, particularly in regard to health care and human costs. He said research over the past decade has led to great strides in understanding foodborne illnesses and preventing, detecting, and responding to outbreaks, and the data in the recently released reports help show what information is still needed.
The reports are available at www.cdc.gov/foodborneburden.