Escherichia Coli General Information

Illnesses of Interest

What is Escherichia coli?

Escherichia coli (abbreviated as E. coli) are a large group of bacteria.
Although most strains of E. coli are harmless, others can make you sick. Some
kinds of E. coli can cause diarrhea, while others cause urinary tract
infections, respiratory illness and pneumonia, and other illnesses. Still
other kinds of E. coli are used as markers for water contamination—so you might
hear about E. coli being found in drinking water, which are not themselves
harmful, but indicate the water is contaminated. It does get a bit
confusing—even to microbiologists.
Some kinds of E. coli cause disease by making a toxin called Shiga toxin. The
bacteria that make these toxins are called “Shiga toxin-producing” E. coli, or
STEC for short.

What are the symptoms of STEC infections?

The symptoms of STEC infections vary for each person but often include severe
stomach cramps, diarrhea (often bloody), and vomiting. If there is fever, it
usually is not very high (less than 101˚F/less than 38.5˚C). Most people get
better within 5–7 days. Some infections are very mild, but others are severe or
even life-threatening.

How soon do symptoms appear after exposure?

The time between ingesting the STEC bacteria and feeling sick is called the
“incubation period.” The incubation period is usually 3-4 days after the
exposure, but may be as short as 1 day or as long as 10 days. The symptoms
often begin slowly with mild belly pain or non-bloody diarrhea that worsens
over several days.

How are these infections spread?

Infections start when you swallow STEC—in other words, when you get tiny
(usually invisible) amounts of human or animal feces in your mouth.
Unfortunately, this happens more often than we would like to think about.
Exposures that result in illness include consumption of contaminated food,
consumption of unpasteurized (raw) milk, consumption of water that has not been
disinfected, contact with cattle, or contact with the feces of infected people.
Some foods are considered to carry such a high risk of infection with E. coli
O157 or another germ that health officials recommend that people avoid them
completely. These foods include unpasteurized (raw) milk, unpasteurized apple
cider, and soft cheeses made from raw milk. Sometimes the contact is pretty
obvious (working with cows at a dairy or changing diapers, for example), but
sometimes it is not (like eating an undercooked hamburger or a contaminated
piece of lettuce). People have gotten infected by swallowing lake water while
swimming, touching the environment in petting zoos and other animal exhibits,
and by eating food prepared by people who did not wash their hands well after
using the toilet. Almost everyone has some risk of infection.

How long can an infected person carry STEC?

STEC typically disappear from the feces by the time the illness is resolved,
but may be shed for several weeks, even after symptoms go away.

How can STEC infections be prevented?

WASH YOUR HANDS thoroughly after using the bathroom or changing diapers and
before preparing or eating food. WASH YOUR HANDS after contact with animals
or their environments (at farms, petting zoos, fairs, even your own
backyard).

COOK meats thoroughly. Ground beef and meat that has been needle-tenderized
should be cooked to a temperature of at least 160°F/70˚C. It’s best to use
a thermometer, as color is not a very reliable indicator of “doneness”.