Infectious disease epidemiologist Kacey Ernst discusses Germany's recent E. coli outbreak.

Germany's recent E.coli outbreak claimed 30 lives and sickened nearly 3,000 people in at least 14 countries before its source was traced to a German farm.

What makes the bacteria so deadly, and why is its origin hard to trace? Kacey Ernst, an infectious disease epidemiologist at the University of Arizona's College of Public Health, joins Arizona Illustrated to explain.

The bacteria that caused the outbreak is commonly found in the digestive tract, she says, and most strains are harmless. Those that cause illness do so because they produce a toxin called a shiga-toxin, and current food production methods makes these easier to spread and harder to trace, she says.

Ernst discusses a similar outbreak involving Jack in the Box hamburgers, and how that incident prompted a turning point in how the U.S. handles E. coli cases. Today the Centers for Disease Control step in when reported cases cross state lines or when the state asks for assistance.

As for what people can do to reduce their risk of becoming infected, Ernst suggests thoroughly cooking meats, keeping food preparation surfaces (such as cutting boards) clean, and properly washing produce before eating it.