TO THE EDITOR:
Swerdlow and colleagues' important study [1] of a water-borne outbreak of Escherichia coli 0157:H7 infection causing diarrhea in 243 patients expands our knowledge of its epidemiology. Yet, the authors report that only 2 of 243 (<1%) patients developed diarrhea-associated hemolytic-uremic syndrome (HUS). This rate is much lower than in previous outbreaks of E. coli 0157:H7 infection. Previous reports of the incidence of diarrhea-associated HUS include 12 of 55 (22%) affected nursing home residents [2], 3 of 36 (8%) children in a daycare center [3], and 8 of 20 (40%) residents of a home for handicapped persons [4].
The criteria for the diagnosis of diarrhea-associated HUS and the laboratory tests used to screen the 243 patients were not specified in the report; we suspect that the incidence of diarrhea-associated HUS was under-reported. Diarrhea-associated HUS is a serious illness with a mortality rate of approximately 5% and significant long-term morbidity (for example, chronic renal failure, neurologic deficits, and diabetes mellitus) in another 10% to 15% [5]. Every patient with diarrhea due to E. coli 0157:H7 infection should undergo urinalysis and have blood tests for hemoglobin concentration, leukocyte count, platelet count, and creatinine level at the time of diagnosis and as necessary if the clinical situation suggests the possibility of diarrhea-associated HUS.
1. Swerdlow DL, Woodruff BA, Brady RC, Griffin PM, Tippen S, Donnell HD Jr, et al. A waterborne outbreak in Missouri of Escherichia coli 0157:H7 associated with bloody diarrhea and death. Ann Intern Med. 1992; 117:812-9.
2. Carter AO, Borczyk AA, Carlson JA, Harvey B, Hockin JC, Karmali MA, et al. A severe outbreak of Escherichia coli 0157:H7-associated hemorrhagic colitis in a nursing home. N Engl J Med. 1987; 317:1496-500.
3. Spika JS, Parsons JE, Nordenberg D, Wells JG, Gunn RA, Blake PA. Hemolytic uremic syndrome and diarrhea associated with Escherichia coli 0157:H7 in a day care center. J Pediatr. 1986; 109:287-91.
4. Pavia AT, Nichols CR, Green DP, Tauxe RV, Mottice S, Greene KD, et al. Hemolytic-uremic syndrome during an outbreak of Escherichia coli 0157:H7 infections in institutions for mentally retarded persons: clinical and epidemiologic observations. J Pediatr. 1990; 116:544-51.
5. Robson WL, Leung AK, Kaplan BS. Hemolytic uremic syndrome. Curr Probl Pediatr. 1993; 23:16-13.
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