E. coli: Understanding the Risk
While most E. coli bacteria are harmless, some strains can cause serious illness. Learn how to protect yourself from dangerous E. coli contamination.
What is E. coli?
Escherichia coli (E. coli) is a type of bacteria that lives in the intestines of humans and animals. Most strains are harmless and are actually an important part of a healthy intestinal tract. However, some types can cause illness.
The strain most often associated with food recalls is E. coli O157:H7, which produces a powerful toxin called Shiga toxin. This strain causes an estimated 73,000 illnesses and 60 deaths in the United States each year.
STEC (Shiga toxin-producing E. coli): This is the category of dangerous E. coli strains that produce toxins. O157:H7 is the most well-known, but other strains like O26, O111, and O103 can also cause severe illness.
Common Sources of E. coli
E. coli O157:H7 and other STEC bacteria can be found in:
High-Risk Foods
- Ground beef and raw beef
- Raw (unpasteurized) milk and cheese
- Raw or undercooked sprouts
- Leafy greens (lettuce, spinach)
- Raw flour and dough
- Unpasteurized juice and cider
Other Sources
- Contaminated water
- Contact with infected animals
- Swimming in contaminated water
- Person-to-person contact
- Petting zoos and farms
Why leafy greens? Contamination often occurs when produce is grown near cattle farms or irrigated with contaminated water. E. coli can also get inside the leaf tissue, where washing cannot reach it.
Symptoms of E. coli Infection
Symptoms typically begin 3 to 4 days after exposure but can range from 1 to 10 days. Most people recover within 5 to 7 days.
Common Symptoms
- Severe stomach cramps
- Diarrhea (often bloody)
- Vomiting
- Fever (usually not high)
Danger Signs - Seek Care
- Bloody diarrhea
- Decreased urination
- Extreme fatigue
- Pale skin
- High fever (over 102°F)
Hemolytic Uremic Syndrome (HUS)
About 5-10% of people diagnosed with STEC infection develop HUS, a serious complication that can cause kidney failure and be life-threatening.
HUS Warning Signs
- Decreased urination
- Extreme tiredness
- Pale skin color
- Easy bruising
- Unexplained bleeding from nose or gums
HUS is most common in children under 5 and older adults. Seek immediate medical attention if you notice these symptoms.
Who is at Highest Risk?
Children Under 5
Most likely to develop HUS. Young children should avoid high-risk foods and practice careful hand hygiene.
Older Adults
Higher risk for serious complications including HUS and hospitalization.
Immunocompromised
People with weakened immune systems face higher risk of severe infection.
Pregnant Women
Should take extra precautions to avoid E. coli exposure due to risks to pregnancy.
How to Prevent E. coli Infection
Cook Ground Beef Thoroughly
Cook ground beef to at least 160°F (71°C). Use a meat thermometer - color alone is not a reliable indicator.
Avoid Unpasteurized Products
Don't drink raw milk or eat products made from raw milk. Choose pasteurized juice and cider.
Wash Produce Carefully
Rinse leafy greens and other produce under running water. Remove outer leaves of lettuce heads. Note: washing may not remove all bacteria.
Don't Eat Raw Dough or Batter
Raw flour can contain E. coli. Don't taste raw cookie dough, cake batter, or any products containing raw flour.
Practice Safe Food Handling
Wash hands thoroughly. Prevent cross-contamination by keeping raw meat separate from ready-to-eat foods.
Wash Hands After Animal Contact
Always wash hands after visiting petting zoos, farms, or touching animals. Supervise children closely.
If You Get Sick
- Stay hydrated. Drink plenty of clear fluids to prevent dehydration from diarrhea.
- Do NOT take anti-diarrheal medications like Imodium or antibiotics without consulting a doctor. These can actually increase risk of HUS.
- See a doctor if you have bloody diarrhea, fever over 102°F, or symptoms lasting more than 3 days.
- Watch for HUS symptoms especially in children under 5. These usually appear about a week after diarrhea starts.
- Practice good hygiene to prevent spreading the infection. E. coli is highly contagious.
Important: Antibiotics are NOT recommended for STEC infections. They may increase the risk of developing HUS. Let your doctor decide on treatment.