E. Coli Outbreaks: Why They Happen, Foods to Avoid

Read on to learn more about common causes of E. coli outbreaks, significant E. coli outbreaks in the past, and ways to protect yourself from E. coli and prevent its spread.

Most E. coli outbreaks are caused by contaminated food. Food contamination occurs when small amounts of bacteria from feces (poop) reach food — for example when a person who works in a restaurant kitchen doesn’t wash their hands properly after using the toilet. But E. coli spreads in other ways, too.

Most Common Food Sources of E. Coli

The most common food sources of E. coli are raw or undercooked ground meat and raw vegetables that haven’t been washed well enough.

Slaughterhouses and meat-packing plants can also spark E. coli outbreaks with unhygienic practices that allow bacteria to spread on equipment and surfaces. For example, E. coli can be passed on from feces if the person handling the meat doesn’t wash their hands properly after using the bathroom.

• Raw or undercooked poultry
• Raw or undercooked tuna
• Unpasteurized dairy products such as raw milk or raw-milk cheeses
• Unpasteurized cider or juice

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• Raw or undercooked eggs
• Raw flour
• Leafy greens such as various types of lettuce, watercress, and arugula
• Slaws and prepackaged salad mixes
• Fruits such as blueberries and strawberries
• Sprouts such as fenugreek sprouts or radish sprouts
• Nuts

• Don’t wash a chopping board on which they’ve prepared raw meat before using it for other foods
• Undercook foods
• Rinse raw meat in the sink
• Don’t wash fruits and vegetables before serving
• Leave perishable food out at room temperature for extended periods, especially in warm environments

Non-Food Sources of E. Coli

Tap Water Fecal contamination can lead to E. coli in tap or well water.

Lake Water Accidentally swallowing water while swimming in a contaminated lake or pond can result in illness.

Animal Contact Contact with infected animals — for example, touching livestock on a farm — can spread E. coli.

Person-to-Person Transmission E. coli can spread through direct contact with a person who has an active infection. Touching the same objects or handling the same food as the person with the infection can spread the bacteria further.

2024 The fast-food chain McDonald’s was involved in an outbreak that caused more than 100 illnesses and one death. E. coli was linked to slivered onions used in the Quarter Pounder burgers.

2024 Organic whole and baby carrots sold at major retailers like Trader Joe’s and Whole Foods were recalled from 18 states after it was determined that they could be contaminated with E. coli. At least 39 people got sick, 15 were hospitalized, and one person died.

• Always clean and disinfect utensils and surfaces in your kitchen.
• Always wash fruit and vegetables thoroughly, especially if you’ll be serving or eating them raw.
• Regularly and thoroughly wash your hands, especially after using the toilet.
• Separate raw foods from cooked foods, and clean cutting boards between uses.
• Have separate cutting boards, one for produce and one for meat and cheese, to avoid cross-contamination.
• Cook food such as meat thoroughly (at temperatures of at least 158 degrees F) and ensure you don’t eat undercooked food.
• Store food at appropriate temperatures.
• Don’t drink water from untreated sources (such as roadside springs), and avoid swallowing water from lakes, streams, and swimming pools.

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• An E. coli outbreak occurs when at least two people develop E. coli infections from the same source.
• Some E. coli strains can cause severe symptoms and even life-threatening complications, especially in more vulnerable populations. But most people who get E. coli experience relatively mild symptoms and recover fully from an infection.
• To prevent E. coli spread, follow good hygiene practices when cooking, avoid high-risk foods like raw milk and undercooked meat, and don’t drink or swallow untreated water.