Correspondence

Contagious Acute Gastrointestinal Infections

N Engl J Med 2005; 352:1267-1268March 24, 2005

Article

To the Editor:

The review of contagious acute gastrointestinal infections by Musher and Musher (Dec. 2 issue)1 is incomplete with respect to bacterial causes of acute gastrointestinal illness. With more than 50 million international travelers a year and rates of incidence of acute diarrhea among such travelers as high as 50 percent,2 enterotoxigenic and enteroaggregative Escherichia coli are important causes of acute bacterial diarrhea, accounting for 30 percent and 26 percent of cases, respectively.3 Enterotoxigenic E. coli and enteroaggregative E. coli infections are spread through water or food contaminated by bacteria from the feces of infected persons.3,4 A high inoculum (10⁸ colony-forming units) supports the role of foodborne transmission.4 The incubation period of these bacterial infections is less than 24 hours. Methods for the diagnosis of enterotoxigenic E. coli infection rely on the detection of the heat-labile or heat-stable enterotoxins, or both. Identification of enteroaggregative E. coli relies on a pattern of aggregative adherence to HEp-2 cells (Figure 1Figure 1HEp-2 Cell Assay for Enteroaggregative E. coli.).5 Diarrhea caused by these bacteria is usually self-limited, with most cases resolving within three days in the absence of treatment. That said, enterotoxigenic E. coli and enteroaggregative E. coli are common bacterial causes of acute gastrointestinal illness that should be considered, especially in travelers to developing countries.

David B. Huang, M.D., M.P.H.
Baylor College of Medicine, Houston, TX 77030
dhuang1@bcm.tmc.edu

5 References

1. 1

   Musher DM, Musher BL. Contagious acute gastrointestinal infections. N Engl J Med 2004;351:2417-2427
   Full Text | Web of Science | Medline

2. 2

   DuPont HL, Ericsson CD. Prevention and treatment of traveler's diarrhea. N Engl J Med 1993;328:1821-1827
   Full Text | Web of Science | Medline

3. 3

   Adachi JA, Jiang ZD, Mathewson JJ, et al. Enteroaggregative Escherichia coli as a major etiologic agent in traveler's diarrhea in 3 regions of the world. Clin Infect Dis 2001;32:1706-1709
   CrossRef | Web of Science | Medline

4. 4

   Huang DB, Okhuysen PC, Jiang ZD, DuPont HL. Enteroaggregative Escherichia coli: an emerging enteric pathogen. Am J Gastroenterol 2004;99:383-389
   CrossRef | Web of Science | Medline

5. 5

   Nataro JP, Kaper JB. Diarrheagenic Escherichia coli. Clin Microbiol Rev 1998;11:142-201[Erratum, Clin Microbiol Rev 1998;11:403.]
   Web of Science | Medline

Author/Editor Response

As we stated in the introductory paragraph of our article, our focus was on infections that spread from one person to another, not on foodborne or waterborne disease. We remain unable to find reports of documented secondary infection — that is, acute gastroenteritis among close contacts of persons who have returned from another country with traveler's diarrhea due to enterotoxigenic or enteroaggregative E. coli — which is why we did not include them in our article.

Considering the frequency of traveler's diarrhea, the absence of evidence of human-to-human spread is all the more notable; in fact, a clinical experiment designed to detect transmission yielded negative results.1 As we emphasized, this lack of contagion is readily understandable in light of the very high inoculum that is needed to transmit these infections.2,3 Although every case of acute gastroenteritis is important to the person who has it, the great majority of cases in the United States occur in persons who have not traveled, and most of these are caused by viruses.

Daniel Musher, M.D.
Michael F. DeBakey Veterans Affairs Medical Center, Houston, TX 77030
daniel.musher@med.va.gov

Benjamin L. Musher, M.D.
University of Pennsylvania School of Medicine, Philadelphia, PA 19104

3 References

1. 1

   Levine MM, Rennels MB, Cisneros L, Hughes TP, Nalin DR, Young CR. Lack of person-to-person transmission of enterotoxigenic Escherichia coli despite close contact. Am J Epidemiol 1980;111:347-355
   Web of Science | Medline

2. 2

   DuPont HL, Formal SB, Hornick RB, et al. Pathogenesis of Escherichia coli diarrhea. N Engl J Med 1971;285:1-9
   Full Text | Web of Science | Medline

3. 3

   Nataro JP, Deng Y, Cookson S, et al. Heterogeneity of enteroaggregative Escherichia coli virulence demonstrated in volunteers. J Infect Dis 1995;171:465-468
   CrossRef | Web of Science | Medline