E. coli O157:H7, as the strain is known, has caused poisonings all over the world. Because it normally inhabits cow intestines, people often become infected by eating carelessly slaughtered beef, or by eating foods exposed to manure-contaminated water. In the United States, the bacterium causes some 20,000 cases of food poisoning a year and more than 250 deaths, especially among children and the elderly. In the worst incident, four children died and more than 700 people became ill in 1993 after eating tainted, undercooked hamburgers at a Jack-in-the-Box in Seattle.
Modern food-supply systems may make people more vulnerable to the bug, says Kazuaki Miyagishima of the World Health Organization’s food safety unit in Geneva. A supply station in Sakai, for example, distributes the same menu to 48,000 schoolchildren each day. So it’s not very surprising that 6,500 children became ill, says Miyagishima. In fact, it would be more surprising if it were a smaller number.


