Washington state health officials said today the outbreak of E. coli had sickened a woman from Longview, who was tested in Oregon. Officials were still investigating and could not say today whether the spinach was purchased in Washington, said Deanna Mill, spokeswoman for the Washington Department of Health.

Federal health officials worked today to find the source of a multistate E. coli outbreak and warned consumers that even washing the suspect spinach won’t kill the sometimes-deadly bacteria.

The death occurred in Wisconsin, where 20 people were reported ill, 11 of them in Milwaukee. The outbreak has sickened others — 10 of them seriously — in Connecticut, Idaho, Indiana, Kentucky, Michigan, New Mexico, Ohio, Oregon and Utah. In California and Washington, health officials were investigating a single case in each of the two states.