E. coli O157:H7
General Information
E.
coli O157:H7 was first
recognized as a human pathogen in 1982 when
it was
found responsible for an outbreak of hemorrhagic colitis in the
United States.1,2
Outbreaks of illness due to this agent have been linked to
consumption of undercooked beef,
apple cider, orange juice, milk, alfalfa sprouts, etc. and
municipal water and swimming pool water.2,3 Person to
person spread is also common, especially in day care centers.
Symptoms
Signs
and symptoms of infection, after an average incubation of 3 to 4
days, include diarrhea and abdominal cramps.2 The
diarrhea can range from non-bloody to nearly entirely blood.
Fever is usually low-grade or absent, unlike most bacterial
diarrheal illnesses, sometimes leading clinicians to suspect
noninfectious etiologies. Strains of E. coli O157:H7 can
produce two types of Shiga toxin or verocytotoxin. These toxins
can cause hemolytic uremic syndrome (HUS) in about 6% of
patients. Currently is this is the major cause of HUS in
children in the United States and Canada.
E. coli O157:H7 in Florida
In
August 1994, small cluster of cases of E. coli 0157:H7
was identified by the Department of Health (DOH) Leon County
Health Department. Further investigation ultimately found eight
confirmed cases from a common source, although none was ever
found.4 Infections with pathogenic serotypes of E.
coli have been reportable in Florida since November 1994.5
In 1995, 44 cases of E. coli O157:H7 infection were
reported to DOH County Health Departments. The highest incidence
of infection that year was in children 1 to 4 years old (1.38
cases per 100,000) and children 5 to 9 (0.86 cases per 100,000).
In all, a total of 585 cases have been reported within the state
of Florida, for an average of 59 cases per year.
In
2005, Florida experienced its most recent outbreak of E. coli
O157:H7, this time linked to petting zoos in the central Florida
area. A total of 29 confirmed cases were linked to this
outbreak. Seventeen of these confirmed cases (60%) occurred in
children less than 5 years old.
The DOH Central Laboratory
provides sub typing support for epidemiologic investigations of
outbreaks caused by E. coli O157:H7 and can perform
pulsed-field gel electrophoresis (PFGE) of isolates. Providers
should also be encouraged to send all isolates of E. coli
O157:H7 to the state laboratory in Jacksonville for DNA
fingerprinting. Laboratory information is being used to identify
Florida specific patterns and to link with PULSENET, a CDC data
system that tracks multi-state outbreaks.
References
1. Benenson AS (ed.). Control
of Communicable Diseases Manual, Sixteenth Edition. United
Book Press, Baltimore, p. 14; 1995.
2. Slutsker L, et al.
Escherichia coli O157:H7 Diarrhea in the United States:
Clinical and
Epidemiologic Features. Ann. Internal Medicine,
Volume 126(7):505-513; 1997.
3. Scheld, W.M., et al (ed.)
Emerging Infections, ASM Press, Washington, D.C.,
1998.
4. Food and Waterborne
Illness Annual Report 1994, Florida Department of Health,
Tallahassee.
5. Florida Morbidity
Statistics 1995. Florida Department of Health, Tallahassee,
pp. 37-38; 995.
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