ATLANTA - Although active surveillance for foodborne disease is just beginning, preliminary results point to an increase in gastrointestinal illnesses in the United States, said Michael Osterholm, PhD, MPH, here at the First International Conference on Emerging Diseases.
"It is disappointing that over the past 50 years we have witnessed an increase of illness, not a decrease," said Osterholm, state epidemiologist and chief of the acute disease epidemiology section Minnesota Department of Health.
It is hard to estimate the burden of gastrointestinal illness (GI), he added, but in Minnesota, it appears to be substantial. "Using the more conservative definition of three or more stools constituting a GI illness, we estimated that there were more than 6.1 million diarrheal illnesses among the 4.4 million people in the state for the one-year period. During this time, an estimated 481,000 ill people sought care by a health care provider; 445,200 people were treated in emergency rooms and 28,400 people were hospitalized overnight. All of these encounters were for diarrheal illness," he said.
There may be many causes for the increase in GI disease, but food would "play an important role," Osterholm said. How much illness is due to food safety issues is difficult to predict, he added.
However, "we must acknowledge that policymakers, industry representatives and the public will continue to ask us in public health and food safety if the food supply is more or less safe than it was yesterday. Unfortunately, we really cannot answer that question. However, the data we do have clearly suggests that not only have we not seen improvements in food safety but also the problem is growing larger."
The reasons are many: changes in diet, commercial food services, new methods of food production, new or re-emerging infections and changing demographics.
Data from the Department of Agriculture (USDA) show that American food expenditures for the share of disposable income from 1970 to 1996 decreased from 14.4% to 11%, but the actual money spent on food increased from $1.1 billion to more than $6.3 billion. "No other industrialized country spends less per capita for food than the United States. For many in our population today, more varieties and volume of food are now available at a cheaper price. And today, we often hear people say in the same breath, `not only do we have the cheapest food in the United States, but we also have the safest.'
"I agree with the conclusion that we have the cheapest food in the world, but since we do have food from around the world, it's hard to understand how food in the United States is much safer from that of any other part of the world," he said.
During this period the types of food consumed in the United States have also changed. Osterholm said there were important food safety implications with the current U.S. diet. People are consuming more fresh fruits and vegetables out of season, which mean more produce is imported from developing countries. In 1970, the per capita consumption of fresh produce was about 175 lbs; by 1995, the annual per capita consumption rose to 220 lbs. "We now chase the sun around the world via developing countries to provide hundreds of desirable produce items on our store shelves 365 days a year," he said.
"While we must be careful not to label all foreign produce as less safe than that raised in the United States, we do know that the risk for traveler's diarrhea for people traveling in one of these developing countries is increased when consuming such items in that country. It is the classic old adage: boil it, peel it or don't eat it," Osterholm said. "We believe we are now seeing an increasing proportion of our illnesses in the United States, which reflect classic traveler's diarrhea for the individual who has never left home."
Contaminated beef and poultry may also cause Escherichia coli, Salmonella, and Campylobacter illnesses.
Commercial food service has also changed. More than 40% of the American food dollar is spent in restaurants, delis and take-out venues. This increases the likelihood of a food handler transmitting a foodborne pathogen. Consider some facts: 77% of Minnesotans surveyed in 1996 reported eating in a restaurant during the five days before the interview. From 1990 to 1996, 69% of confirmed foodborne outbreaks in Minnesota were attributed to a licensed food service operation. An increase in exposures increases the likelihood of contracting a foodborne illness, but many of these outbreaks are sporadic and not easily recognized.
"Today, the average food handler in this country makes minimum wage, lacks sick leave or other health benefits and has an absence of advancement opportunities. The type of person attracted to these positions is frequently a high school student or others who are among our lowest socioeconomic status groups in the country. This is the same population that we tend to see the highest incidence of many enteric diseases and the lowest rates of routine handwashing," Osterholm explained.
There have been changes in the method of food production as well. For instance,Salmonella in shell eggs has been a problem for some time. To combat this, a growing proportion of eggs are being converted to pasteurized egg product. Although more than 28% of all egg product consumed in this country is pasteurized and pasteurized egg product is recommended for the immunocompromised, the egg product is not entirely safe. The pasteurizing process for eggs is different than for milk - the temperature is not as high. As a result, not all of the Salmonella is killed. USDA studies found up to 1% of post-pasteurized egg product has Salmonella.
"The fourth factor that contributes to the epidemiology of foodborne diseases is new and re-emerging agents, including E. coli O157:H7, Campylobacter jejuni, Toxoplasma gondii and E. coli 39:NM," Osterholm said, adding that Norwalk virus may be the leading cause of foodborne disease today.
There continues to be an increase of E. coli O157:H7 cases, and consumption of undercooked hamburger remains the main cause. "It is not OK to eat pink hamburger or pork; somehow we have to convey that information to the public," he insisted.
Many physicians believe that laboratories routinely test for E. coli; they do not. And E. coli O157:H7 is not the only strain that should cause concern. Osterholm said E. coli O39:NM should also be of concern.
With an increase in the consumption of chicken, Campylobacter infections are also on the rise, Osterholm said, and T. gondii is an unrecognized cause of foodborne illness. He believes there are a number of new and re-emerging diseases.
As Baby Boomers age, their chances of suffering GI illness increases because they are more likely to have immunocompromised conditions, such as cancer, leaving them susceptible to opportunistic foodborne illnesses. "Age brings on many changes besides wrinkles and hair loss and expanding waistlines," he said.
It is time for Americans to be more concerned about food production in general, not just food produced in the United States. "While we are concerned with the importation of safe food products into our country, more than 50 million Americans traveled somewhere outside of the United States. The safety and integrity of the world's food supply should be a priority for us because an increasing number of us travel around the world."
He recommended increased surveillance for existing and emerging foodborne pathogens, more community based studies and a better network to detect and respond to outbreaks. He called the government response to outbreaks "fragmented."
In addition, public health and industry must work together to promote safe food and better water quality in this country. One way to assure safer food is to use ionized irradiation, which Osterholm said has been studied more extensively than microwaving, freezing and canning. However, industry is reluctant to use the technology because some groups are vigorously opposed to it "out of fear, not fact," he said.
In addition, the public must be taught the causes of foodborne illness and how to protect themselves.
For more information:
- Osterholm M. Foodborne diseases: are they really emerging infections? Presented at the International Conference on Emerging Infectious Diseases. March 8-11. Atlanta.
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