Technical Information
Technical information is taken directly from the December 2001 CDC
Division of Bacterial and Mycotic Diseases: Escherichia coli O157:H7
Clinical Features
Acute bloody diarrhea and abdominal cramps with little or no fever; usually
lasts 1 week.
 |
| Transmission electron
micrograph of Escherichia coli O157:H7 (1995) |
Etiologic Agent
Escherichia coli serotype O157:H7. Gram-negative rod-shaped bacterium
producing Shiga toxin(s).
Incidence
An estimated 73,000 cases occur annually in the United States. Uncommonly
reported in patients in less industrialized countries.
Transmission
Major source is ground beef; other sources include consumption of unpasteurized
milk and juice, sprouts, lettuce, and salami, and contact with cattle.
Waterborne transmission occurs through swimming in contaminated lakes,
pools, or drinking inadequately chlorinated water. Organism is easily
transmitted from person to person and has been difficult to control in
child day-care centers.
Risk Groups
All persons. Children < 5 years old and the elderly are more likely
to develop serious complications.
Surveillance
E. coli O157:H7 infection is nationally reportable and is reportable
in most U.S. states. HUS is also reportable in most states.
Challenges
Developing farm and slaughterhouse-based methods to decrease contamination
of meat; encouraging use of irradiation to increase the safety of ground
beef; identifying ways to prevent contamination of foods eaten raw (e.g.,
produce); educating the U.S. public to cook ground beef thoroughly, preferably
using a digital instant-read thermometer; convincing clinical laboratories
to screen for E. coli O157:H7 in stools from persons with bloody
diarrhea; conducting population-based surveillance for HUS and determining
which serotype of Shiga toxin-producing E. coli was responsible
for illness; identifying other vehicles of transmission; developing an
international network for subtyping and communicating about outbreaks.
Opportunities
Learning more about the ecology of this organism in cattle and other ruminants
may help in devising methods to decrease its prevalence in food animals.
Learning how this pathogen contaminates produce items could lead to measures
that would increase their safety. Decreasing the incidence of these infections
would decrease HUS, the major cause of kidney failure in children in the
United States. Transmission in day-care centers highlights need for better
infection-control practices.
Additional Resources
Frequently
Asked Questions about Escherichia coli O157:H7
Center
for Disease Control and Prevention Food Safety Threat
NOTE: All images taken from the CDC
Public Health Image Library website.
|
