CASES/YEAR
73,480 (US); 1,469,600 (Global)
OTHER NAMES
E. coli O157:H7; Escherichia coli O157:H7; Enterohemorrhagic E. coli; EHEC; Shiga toxin producing E. coli (STEC);
INCUBATION
1-10 days; usually 3-4 days; [CDC Travel]
INITIAL SYMPTOMS
Bloody diarrhea with abdominal cramping and little or no fever usually lasting one week; 2-8% of cases are complicated by hemolytic-uremic syndrome 2-14 days after onset of diarrhea; [Harrison ID, p. 513]
PRECAUTIONS
Standard; "Use Contact Precautions for diapered or incontinent persons for the duration of illness or to control institutional outbreaks." [CDC 2007 Guideline for Isolation Precautions]
COMMENTS
FINDINGS:
Approximately 15% of children with EHEC develop hemolytic-uremic syndrome (HUS), the major cause of kidney failure in children in the USA. 50% of HUS patients require dialysis. Other complications are bowel ischemia, stroke, and thrombotic thrombocytopenic purpura (TTP). [CCDM, p. 158; CDC web site] HUS consists of thrombocytopenia, microangiopathic hemolytic anemia, and acute renal failure. EHEC is the most common cause of HUS in children. [Cohen, 1572] Jaundice is a finding in patients with hemolytic-uremic syndrome. [Cohen, 3rd Ed, p. 1081] This infection, along with Shigella, C. jejuni, and nontyphoidal Salmonella, are the major causes of bloody diarrhea in the USA. [PPID. 8th Ed, p. 1243] EHEC bloody diarrhea often occurs without fever. Leukocytosis often accompanies the onset of HUS. The Shiga toxins that cause HUS can also cause ischemia to other organs (brain, eyes, and colon). "The HUS and thrombocytopenia may occur 2 to 4 days after the onset of diarrhea, especially in children younger than 5 years and in older adults." [PPID, p. 1359; 2675-6] The onset of HUS occurs in about 6% of infections (15% in children <5 years of age), typically about 1 week after the diarrhea began. [PPID, p. 1384] Fecal leukocytes or lactoferrin in (30-40%) and fever in (0-30%) of cases; [Guerrant, p. 112] Other strains of E. coli that cause gastroenteritis are enterotoxigenic (See Cholera.); enteroinvasive (See Shigellosis.); enteropathogenic; and enteroaggregative. The last two mentioned strains cause infant diarrhea in developing countries. [CCDM, p. 163-72]
MICROANGIOPATHIC HEMOLYTIC ANEMIA:
Platelet aggregates cause ischemia of multiple organs, thrombocytopenia, and fragmentation of red cells. [Wallach, p. 1054] Findings include: 1.) hemoglobin level typically <8 g/dL; 2.) platelets typically <60,000/uL; and 3.) acute renal failure (about 55-70% of cases) caused by thrombosis of glomerular capillaries. Anemia is severe, and blood smears show fragmented RBCs (schizocytes). [Harrison ID, p. 546] The brain (strokes), eyes (blindness), and colon (ischemia) may also be affected. [PPID, 8th Ed, p. 2512] "Seizures may be common." [ABX Guide]
EPIDEMIOLOGY:
Patients with hemolytic-uremic syndrome have 3-5% mortality. [Gorbach, p. 157] A diagnosis of EHEC should trigger an outbreak investigation. [PPID, p. 2676] Cattle are the most important reservoir, also sheep, goats, and deer. Occasionally, birds, pigs, and other animals may spread infection to humans. Disease has occurred after consuming undercooked hamburger, unpasteurized milk, and contaminated apple cider, sprouts, lettuce, fresh spinach, and salami. Transmission has also occurred from swimming in contaminated pools and lakes and drinking contaminated water. The disease may spread between children in daycare centers. [CCDM, p. 158-63; CDC web site] Children may be infected after touching animals on farms or in petting zoos. [PPID, p. 2675] The primary reservoir of Shiga toxin-producing E. coli are the intestines of animals, especially cattle and other ruminants. [CDC Travel, p. 207] In the USA, about 90% of all HUS cases in children are caused by STEC/EHEC. [Harrison ID, p. 513] E. coli O157:H7, salmonella, and shigella are possible agents of bioterrorism. [www.bt.cdc.gov]
DIAGNOSTIC
Culture on special media; Confirm with immunoassays for Shiga toxin or PCR for stx genes; [PPID, p. 2676] Evaluate all bloody diarrhea for presence of Shiga toxin; [ABX Guide: Escherichia coli]
SIGNS & SYMPTOMS
-
>fever
-
G abdominal pain
-
G blood in stool
-
G diarrhea
-
G fecal leukocytes
-
G jaundice
-
G nausea, vomiting
-
H anemia
-
H hemolysis
-
H leukocytosis
-
H thrombocytopenia
-
N seizure
-
*acute renal failure
-
*blindness
ENTRY
Ingestion, Swimming
SOURCE
Person-to-Person, Human Fecal-Oral, Eating Contaminated Food, Eating Contaminated or Infected Meat, Eating Unpasteurized Milk or Cheese, Eating Contaminated Produce, Waterborne (Ingesting, Inhaling, or Swimming)
RESERVOIR
Birds and Poultry, Cattle, Goats and Sheep, Cats, Deer, Elk and Antelope, Dogs, Horses, Rabbits, Swine, Human, Wild Animals
RISK FACTORS
- Consume unpasteurized milk/cheese
- Eat undercooked meat or fish
- Ingest infectious agents in food/water
- Swim in contaminated water (ingestion or inhalation)
- Victim--water/food release
TREATMENT
Antibiotics are not recommended. [PPID, p. 2676] "Evidence from studies of children with STEC O157 infection indicates that early use of intravenous fluids (within the first 4 days of diarrhea onset) may decrease the risk of oligoanuric renal failure. . . . Clinicians treating a patient whose clinical syndrome suggests STEC infection (Table 4-1) should be aware that administering antimicrobial agents may increase the risk of HUS." [CDC Travel, p. 209]
REFERENCES FOR CASES/YEAR
1. (US) Published in MMWR 2011; 6047; 1.19 cases per 100000 in 2007; [Gorbach, p. 10] Calculate for population of 300 million = 3570; Estimated 73,480 cases in 1997; [Mead1999: PMID 10511517]
2. (Global) STEC/EHEC infections are more common in industrialized countries. [Harrison ID, p. 513] Guesstimate: Assume global rate = 20 X US rate;