E. coli 0157:H7 Part 1 - Transmission

Transmission of E. coli O157:H7

“Enterohemorrhagic” describes the bacterium’s ability to damage the intestine and cause bloody diarrhea. O157:H7 is a particularly virulent strain of E. coli.

Animal sources

The bacteria are found mainly in the feces of healthy beef and dairy cattle, but pigs, poultry, and sheep can also carry them. Animal waste can contaminate food and water.

Foodborne transmission

Infection often follows eating meat contaminated with feces. Ground beef must be thoroughly cooked because grinding can mix bacteria from the meat’s surface into its interior. By contrast, cooking the outer surface of an intact steak can kill bacteria on the outside, even if the center remains rare.

Produce can also become contaminated when animal waste reaches fields or crops. The video gives the example of deer contaminating strawberries. Other foods implicated in outbreaks include unpasteurized milk and cheese, chicken, fruit juice, sprouts, spinach, lettuce, tomatoes, flour, and soy nut butter.

Outbreak history

The first outbreak mentioned occurred in 1982 and was linked to contaminated hamburgers at fast-food restaurants. A major outbreak in 1993 involved 73 Jack in the Box restaurants across Idaho, Washington, Nevada, and California. The video reports 732 infections, 171 hospitalizations, lasting kidney problems in many patients, and four child deaths.

The outbreak prompted regulatory changes to hamburger preparation and cooking, though outbreaks have continued.

Waterborne and person-to-person transmission

The bacteria can survive in water for long periods, especially at lower temperatures. People may become infected by drinking contaminated lake or stream water or by swallowing water while swimming.

Person-to-person transmission has been reported in settings such as nursing homes and daycare centers.

Infectious dose

The infectious dose is low—estimated in the video at 10–100 colony-forming units (CFU)—so a small amount of contaminated food or water may be enough to cause infection.

Speaker and source

A single, unnamed narrator presents the video’s explanation. No other speakers or sources are identified in the subtitles.