Every so often you hear of people getting sick with E. coli from the food at a catered party or a popular restaurant chain. But how much do you know about this nasty bacteria, the symptoms of E. coli infection — and how to avoid getting sick?

The good, the bad, and the ugly

The good: Escheria coli helps keep our intestinal tract healthy, according to the Centers for Disease Control and Prevention (CDC). Most varieties of the bacteria, which lives in the guts of people and animals, are harmless or cause only mild diarrhea.

The bad: Some strains are dangerous, including E. coli 026, the culprit behind multistate outbreaks linked to a giant Mexican food chain in 2015.

Related: How Social Media Can Help Identify Food Poisoning Outbreaks

The ugly: E. coli 026 produces Shiga toxin. This toxin attacks red blood cells and triggers a urinary disorder that can leads to kidney failure. The disorder — hemolytic uremic syndrome, or HUS — can also result in stroke, seizure, coma and even death.

In earlier outbreaks, E. coli 0157, which also products Shiga toxin, sickened people after they ate foods contaminated with the bacteria, including tainted pizza, beef patties and spinach. Contaminated spinach killed three people in 2006.

Per the CDC, "When you hear news reports about outbreaks of “E. coli” infections, they are usually talking about E. coli 0157."

Related: 9 Surprising Places Salmonella Bacteria Lurk

Symptoms of E. coli infection

People usually get sick from a Shiga toxin-producing E. coli (STEC) an average of three to four days after they swallow the bacteria. The most common symptoms include:

  • Stomach tenderness and severe stomach cramps
  • Water diarrhea that often becomes bloody
  • Nausea and vomiting

If you have a STEC infection linked to E. coli, your doctor can likely diagnose it through a stool sample.

The CDC recommends getting emergency medical care immediately if you develop symptoms of the dangerous urinary disorder HUS, which include:

  • Fever
  • Abdominal pain
  • Pale skin
  • Fatigue and irritability
  • Bleeding from the nose and mouth
  • Small bruises with no apparent cause
  • Decreased urination

Preventing E. coli infection

So how can you help protect yourself? The CDC has this advice.

Know your risk. You’re at a higher risk for foodborne illness if you are pregnant or an older adult or have a weakened immune system. Babies and children are also at higher risk.

See your healthcare provider if you think you have an E. coli infection.

Wash your hands. E. coli is found in feces, so be sure to wash your hands thoroughly:

  • after using the bathroom, changing diapers and before preparing or eating food
  • after touching an animal or visiting a farm, petting zoo or animal fair
  • before preparing and feeding bottles or foods to a baby, before touching a baby’s mouth and before touching pacifiers

Use an alcohol-based hand sanitizer if soap and water aren't available.

Wash pacifiers and teethers, as well as and any other toy a baby puts in her mouth.

In the kitchen, follow clean, separate, cook and chill guidelines, which you can find at FoodSafety.gov.

Cook meats thoroughly. Ground beef and meat that has been needle-tenderized should be cooked to a temperature of at least 160°F. Use a meat thermometer to test it.

Prevent cross-contamination when cooking by thoroughly washing hands, counters, cutting boards and utensils after they touch raw meat.

Avoid consuming raw milk, unpasteurized dairy products and unpasteurized juices.

Avoid swallowing water when swimming in lakes, ponds, swimming pools, splash parks and backyard "kiddie" pools.

Related: Proper Hand Washing 101: What’s the Best Way to Kill Germs?

Diana is an award-winning writer and editor with more than 20 years' experience in magazine, video, book and digital journalism, with a specialty in health coverage. She was a longtime writer and news editor at the Center for Investigative Reporting; has written for publications from the Washington Post to the Times of London syndicate; and has served as a senior and/or consulting editor at Time Inc. Health, Hippocrates, HealthDay News Service and Reporting on Health. She was also editor in chief of Consumer Health Interactive, a national health and medical web site, and has reported on finance for Blueshift Research and PBS Frontline. Before joining SafeBee, she was editor of Bioenergy Connection, a national magazine about bioenergy at UC Berkeley. Her favorite safety tip: Wear a bike helmet.