Yesterday, an Idaho woman was added to the list of people who became ill with E. coli O157:H7 infections after eating ground beef produced by a Clackamas, Oregon meat producer and consumers were warned to check their freezers for potentially contaminated ground beef products. Illnesses associated with the outbreak have been reported in Idaho, Oregon, and Washington.

This morning, Alex Pulaski of the Oregonian reported that a Bend, Oregon, resident helped Oregon health officials determine the source of her E. coli illness and establish a link to the Washington and Idaho cases.

Amber Wark, one of the family members who had fallen ill, discovered a telling clue Saturday morning while taking it on herself to rummage through a dozen garbage bags in a trailer bed: packaging for 4 pounds of ground beef.

The wrappers led state epidemiologists, federal agricultural inspectors and Washington health authorities back to Interstate Meat Distributors Inc. in Clackamas, which had ground the meat that Wark bought July 29 at Safeway.