Changing challenges of bacterial enteric infection in the United States.

The vast majority of bacterial enteric infections in the United States are sporadic, yet much of what is known about the epidemiology of these infections is driven by investigations of outbreaks. Studying sporadic infection is challenging, but critically important. The article by Denno et al. [1] in this issue of the Journal highlights the need for ongoing studies to understand the rapidly evolving epidemiology of sporadic bacterial enteric infection. Their work identifies a number of newly recognized risk factors for infection in children, who suffer from the highest rates of disease, and provides important data to help develop focused interventions. We live in a society in which 46% of the US food dollar is spent on food prepared outside the home [2], fresh produce travels an average of 1500 miles to reach our plates [3], a typical dinner includes ingredients from around the world, and convenience-packaged foods are increasingly popular. The nature of enteric disease outbreaks, a large proportion of which are foodborne, continues to evolve along with our food supply system. The sources of sporadic infection are likely to be changing in a similar fashion. At the same time, however, there is increasing evidence that a variety of non-food exposures are important risk factors for infection in children. Controlling such risk factors in this population is particularly challenging and important. While Campylobacter is the most common cause of bacterial enteric infection in the United States [4], outbreaks of infection are relatively rare and identifying the causes of sporadic infection is particularly problematic. Rates of campylobacteriosis vary dramatically, not only by state but also among adjacent jurisdictions within states, for unknown reasons. In the Denno et al. [1] study, a large number of risk factors for Campylobacter infection were identified. They included domestic travel, consumption of various foods, eating out, home food-handling practices, and various contacts with animals, water, and ill humans. With such a diverse array of risk factors, identifying interventions that will have a substantial effect on overall rates of this disease will be especially challenging. Restaurant-associated outbreaks often attract substantial public attention. However, this work adds to the growing body of data suggesting that sporadic infection due to a variety of pathogens is also associated with eating at commercial food venues [5]. It is also one of the first studies to identify this as a risk specifically in children. If the proportion of the American diet prepared outside the home continues its steady growth, better understanding of this association will become increasingly important. Several of the findings in this study are of particular interest in light of a number of recent high-profile, produce-associated outbreaks in the United States. Raw vegetable consumption appeared to be protective against Salmonella infection in this population, which is reassuring in the context of trying to encourage children to eat a diet high in fruits and vegetables for its many other health benefits. Of potentially great interest is the additional protection afforded by organic produce. Lower risk of infection is not a welldocumented benefit of these products, and the finding is provocative as they become increasingly popular. All this said, the produce story is not a straightforward one. This study shows for the first time that salad from sealed retail packages, which has been a cause of large outbreaks, is also a risk factor for sporadic disease. Prevention of produce contamination is a difficult challenge and is currently the focus of intense discussion at the political, industry, and public health levels. It will be important to understand the particular risks associated with convenience packaging as consumer demands continue to Received 2 November 2008; accepted 5 November 2008; electronically published 26 January 2009. Potential conflicts of interest: none reported. Financial support: none reported. Reprints or correspondence: Timothy Jones, MD, Communicable and Environmental Disease Services, TN Department of Health, 1st Floor, Cordell Hull Bldg. , 425 5th Ave. N. , Nashville, TN 37243 (tim.f.jones@state.tn.us). The Journal of Infectious Diseases 2009; 199:465– 6 © 2009 by the Infectious Diseases Society of America. All rights reserved. 0022-1899/2009/19904-0001$15.00 DOI: 10.1086/596556 E D I T O R I A L C O M M E N T A R Y