Volume 17, Number 7—July 2011
Letter
Foodborne Illness Acquired in the United States
To the Editor: The updated estimates of foodborne illness in the United States reported by Scallan et al. probably overestimate the occurrence of illness caused by unspecified agents because they did not account for the apparent sensitivity of the population survey to the occurrence of norovirus (1,2). The number of illnesses attributed to unspecified agents was derived from the simultaneous processes of extrapolation and subtraction: extrapolation from the population survey to create a base of diarrheal illnesses and subtraction of known agents from this base. Scallan et al. averaged illness rates from 3 successive population surveys to come up with a rate of 0.6 episodes of acute gastroenteritis per person per year. However, the individual rates were 0.49 (2000–2001), 0.54 (2002–2003), and 0.73 (2006–2007). The 2006–2007 survey was conducted at the time of widespread norovirus activity. The estimated rate of population illness was strongly correlated with the number of confirmed and suspected norovirus outbreaks reported to the Centers for Disease Control and Prevention Foodborne Disease Outbreak Surveillance System during each of the survey periods (300, 371, and 491, respectively; R2 = 0.97, p<0.0001). No other known agents were correlated with the population survey rates, and the total numbers of outbreaks were inversely correlated with the population survey data.
The strength of the correlation between norovirus outbreaks and survey results suggests that the population survey is sensitive to norovirus activity and that norovirus may account for much of what is considered to be unspecified. The fact that the highest observed population rate was ≈50% greater than the lowest rate suggests that annual variation in norovirus activity may account for a considerable proportion of what otherwise seems to be unspecified. More thorough and timely investigation and reporting of outbreaks could facilitate the development of models to evaluate the number of illnesses and update them annually.
References
- Scallan E, Hoekstra RM, Angulo FJ, Tauxe RV, Widdowson MA, Roy SL, Foodborne illness acquired in the United States—major pathogens. Emerg Infect Dis. 2011;17:7–15.PubMedGoogle Scholar
- Scallan E, Griffin PM, Angulo FJ, Tauxe RV, Hoekstra RM. Foodborne illness acquired in the United States—unspecified agents. Emerg Infect Dis. 2011;17:16–22.PubMedGoogle Scholar
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To the Editor: The report by Scallan et al. provides a valuable update regarding estimated annual illnesses, hospitalizations, and deaths caused by recognized foodborne pathogens, most of which cause diarrheal disease, in the United States (1). However, absent from this study, and from most previous reviews of foodborne illness, was attention to possible extraintestinal disease, especially antimicrobial drug–resistant infections caused by food-source Escherichia coli and associated resistance elements.
A growing body of molecular and epidemiologic evidence suggests that a substantial fraction of extraintestinal E. coli infections in humans, particularly those involving antimicrobial drug–resistant strains, might be caused by E. coli from food animals (2). Extraintestinal pathogenic and antimicrobial drug–resistant E. coli commonly contaminate retail meat products (3,4); rates of contamination and resistance associated with “no antibiotics” production methods, labeling, and markets are lower (4). In a study of women with acute urinary tract infection, frequent consumption of chicken and pork was associated with isolation of antimicrobial drug–resistant E. coli from urine (5).
Extraintestinal E. coli infections, which include urinary tract infections and sepsis, are more common and result in more hospitalizations and deaths than do infections caused by the classic foodborne pathogens. For example, each year in the United States, an estimated 40,000 deaths are associated with sepsis caused by extraintestinal E. coli infection (6); only <1,400 deaths are caused by all major classic foodborne pathogens combined (1). Therefore, if even a modest fraction (e.g., 5%–10%) of all extraintestinal E. coli infections in humans are of foodborne origin—which seems highly plausible, considering the molecular evidence (2)—the extent of associated disease may equal or exceed that attributable to the classic foodborne pathogens as estimated by Scallan et al. Greater recognition of this possibility by the public health system is needed so that appropriate attention can be devoted to this neglected, invisible foodborne disease threat.
References
- Scallan E, Hoekstra R, Angulo FJ, Tause RV, Widdowson M-A, Roy SL, Foodborne illness acquired in the United States—major pathogens. Emerg Infect Dis. 2011;17:7–15.PubMedGoogle Scholar
- Johnson JR, Sannes MR, Croy C, Johnston B, Clabots C, Kuskowski MA, Antimicrobial drug–resistant Escherichia coli isolates from humans and poultry products, Minnesota and Wisconsin, 2002–2004. Emerg Infect Dis. 2007;13:838–46. DOIPubMedGoogle Scholar
- Johnson JR, McCabe JS, White DG, Johnston B, Kuskowski MA, McDermott P. Molecular analysis of Escherichia coli from retail meats (2002–2004) from the United States National Antimicrobial Resistance Monitoring System (NARMS). Clin Infect Dis. 2009;49:195–201. DOIPubMedGoogle Scholar
- Johnson JR, Kuskowski MA, Smith K, O’Bryan TT, Tatini S. Antimicrobial-resistant and extraintestinal pathogenic Escherichia coli in retail foods. J Infect Dis. 2005;191:1040–9. DOIPubMedGoogle Scholar
- Manges AR, Smith SP, Lau BJ, Nuval CJ, Eisenberg JN, Dietrich PS, Retail meat consumption and the acquisition of antimicrobial resistant Escherichia coli causing urinary tract infections: a case–control study. Foodborne Pathog Dis. 2007;4:419–31. DOIPubMedGoogle Scholar
- Russo TA, Johnson JR. Medical and economic impact of extraintestinal infections due to Escherichia coli: focus on an increasingly important endemic problem. Microbes Infect. 2003;5:449–56. DOIPubMedGoogle Scholar
- Hedberg CW. Foodborne illness acquired in the United States [letter]. Emerg Infect Dis. 2011;17:1338. DOIPubMedGoogle Scholar
- Johnson JR. Foodborne illness acquired in the United States [letter]. Emerg Infect Dis. 2011;17:1338–9. DOIPubMedGoogle Scholar
- Scallan E, Hoekstra RM, Angulo FJ, Tauxe RV, Widdowson MA, Roy SL, Foodborne illness acquired in the United States—major pathogens. Emerg Infect Dis. 2011;17:7–15.PubMedGoogle Scholar
- Scallan E, Griffin PM, Angulo FJ, Tauxe RV, Hoekstra RM. Foodborne illness acquired in the United States—unspecified agents. Emerg Infect Dis. 2011;17:16–22.PubMedGoogle Scholar
- Manges AR, Smith SP, Lau BJ, Nuval CJ, Eisenberg JN, Dietrich PS, Retail meat consumption and the acquisition of antimicrobial resistant Escherichia coli causing urinary tract infections: a case–control study. Foodborne Pathog Dis. 2007;4:419–31. DOIPubMedGoogle Scholar
- Widdowson MA, Cramer EH, Hadley L, Bresee JS, Beard RS, Bulens SN, Outbreaks of acute gastroenteritis on cruise ships and on land: identification of a predominant circulating strain of norovirus—United States, 2002. J Infect Dis. 2004;190:27–36. DOIPubMedGoogle Scholar
Table of Contents – Volume 17, Number 7—July 2011
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